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Habitus of the larvae of Hydrophilini, dorsal view. A-B-Hydrochara affi nis (Sharp, 1873): A-fi rst instar; B-third instar. C-Hydrophilus acuminatus Motschulsky, 1854, third instar. D-E-Sternolophus (Sternolophus) rufi pes (Fabricius, 1792): D-second instar; E-third instar.
Source publication
Larval morphology of the Japanese representatives of the tribes Acidocerini, Hydrobiusini and Hydrophilini (Coleoptera, Hydrophilidae, Hydrophilinae) is described. Eleven species assigned to seven genera are studied: Agraphydrus narusei (Satô, 1960) (first and third instars), Enochrus (Holcophilydrus) simulans (Sharp, 1873) (all instars), E. (H.) u...
Contexts in source publication
Context 1
... lateral lobes of spiracular atrium, a pair of acrocerci and prostyli. Most species have a single dorsal plate on the abdominal segment 8 (e.g., Figs. 5, 9B); the dorsal plate of Hydrophilus is subdivided into two isolated sclerites (Fig. 58B). Shape of the posterior margin of dorsal sclerite is variable, e.g., almost rounded in Enochrus (e.g., Fig. 25B), quadrilobate in Hydrochara (Fig. 54B). Prostyli are reduced or absent in the most species, only Hydrochara and Hydrophilus have long, membranous prostyli (Figs. 54B, 58B). Abdominal segment 10 is reduced, situated on the ventral surface of the spiracular ...
Context 2
... Dorsal surface of head capsule without densely arranged, strong tooth-like cuticular projections (Figs. 9A, 25A, 35A). Frontal lines V-shaped to lyriform, converging towards base of head capsule (Figs. 9A, 16A, 29A); coronal line present. Epistomal lobes not or moderately extended anteriorly, setation of lobes on both sides more or less similar (e.g., Figs. 10C, 24A, 29C). Shape of nasale variable (serrate or with at least two teeth; Figs. 7C, 13C, ...
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... Sensorium (SE1) on intersegmental membrane between scape and pedicel (Figs. 11A, 24B, 30A, 40B). Stipes with one to several cuticular proje- ctions, never with densely arranged cuticular projections on most of inner face (Figs. 11D-E, 15F-G, 31E-F). Labium without well developed hypopharyngeal lobe; mentum less than twice as wide as prementum (Fig. 26G); anterior corners of mentum not projecting anteriad (Figs. 26G, 30F). Ligula well developed (e.g., Figs. 8F, 21F, 30F). Anterior margin of proscutum without fringe of long setae (e.g., Figs. 6, 51). Proscutum without lateral lobes. Legs moderately short to rather long, well developed, without fringes of long swimming hairs (Fig. 45). ...
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... pedicel (Figs. 11A, 24B, 30A, 40B). Stipes with one to several cuticular proje- ctions, never with densely arranged cuticular projections on most of inner face (Figs. 11D-E, 15F-G, 31E-F). Labium without well developed hypopharyngeal lobe; mentum less than twice as wide as prementum (Fig. 26G); anterior corners of mentum not projecting anteriad (Figs. 26G, 30F). Ligula well developed (e.g., Figs. 8F, 21F, 30F). Anterior margin of proscutum without fringe of long setae (e.g., Figs. 6, 51). Proscutum without lateral lobes. Legs moderately short to rather long, well developed, without fringes of long swimming hairs (Fig. 45). Abdominal segments without lateral projection and tracheal gills ...
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... of the Japanese species of Chasmogenus Sharp, 1882 are still unknown, therefore, we refer to ANDERSON (1976) for the genus; larvae of the genus Megagraphydrus Hansen, 1999 are also still unknown (see Table 1). (Fig. 24A) (Figs. 7C, 10C). ............... Agraphydrus Régimbart, 1903 -Nasale almost symmetrical (ANDERSON 1976: Fig. 9) General morphology. Third instar. Body slender, almost parallel-sided (Fig. 1A). Colour. Head and sclerotised parts light yellowish brown; membranous parts milky white (Fig. 1A). Head (Fig. 9A). Head capsule subquadrate. ...
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... without long scale-like setae; 2) nasale serrate (Figs. 13C, 26A); 3) antennal sensorium (SE1) rather long (in fi rst instar; Fig. 14A) to small (in third instar; Fig. 17B); 4) mandibles asymmetrical, left mandible with only one inner tooth or with one large and one small inner teeth (e.g., Figs. 17C-D); 5) abdominal segments with spinose prolegs (Fig. ...
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... Head capsule subquadrate (Fig. 25A). Frontal lines nearly V-shaped (Fig. 13A) to weakly lyriform (Fig. 19A), fused at base of head capsule, coronal line short. Surface of head capsule smooth. Six stemmata on each anterolateral portion of head capsule. Clypeolabrum asymmetrical (Fig. 20C). Nasale serrate, sometimes with distinct tooth on both sides. Ante- rior margin of ...
Context 8
... Head capsule subquadrate (Fig. 25A). Frontal lines nearly V-shaped (Fig. 13A) to weakly lyriform (Fig. 19A), fused at base of head capsule, coronal line short. Surface of head capsule smooth. Six stemmata on each anterolateral portion of head capsule. Clypeolabrum asymmetrical (Fig. 20C). Nasale serrate, sometimes with distinct tooth on both sides. Ante- rior margin of epistome asymmetrical, projecting anteriorly on inner portion, then straight to ...
Context 9
... anterior one; remaining two sclerites very small, sometimes undetectable, in posterior part of segment; each small sclerite bearing rather long seta; lateral sclerites of segment 1 very small (Fig. 3). Segments 3 to 7 with spinose prolegs; shape of spines variable, from stout and strongly curved (Figs. 28A-D) to slender and not strongly curved (Figs. ...
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... Abdominal segments 2 to 7 similar to segment 1 except anteromedian part with only one small sclerite, lateral sclerites narrow, very small; segments 3 to 7 with spinose prolegs, spines of prolegs stout, strongly curved apically (Fig. 28C). (Fig. 16B): Segment 8 with large, oval dorsal plate, posterior edge of plate almost rounded, bearing four very weak projections, each projection with one moderately short stout seta; procercus incompletely sclerotised, with two rather long and one short setae. Second instar. Similar to third instar larva, more weakly sclerotised than ...
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... Abdominal segments 2 to 7 similar to segment 1 but anteromedian part with only one small, oval dorsal sclerite on each side; lateral sclerites narrow, very small; segments 3 to 7 with spinose prolegs, spines of prolegs stout, strongly curved at apex (Fig. ...
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... of head. Third instar. Frontale altogether with 42 primary sensilla and two secondary sensilla (Figs. 20A, C). One short secondary seta at midlength between FR1 and FR5. Rather short setae (FR5 and FR6) behind antennal socket. Second seta of gFR1 of right side shorter than others. Anterior margin of epistomal lobes each with two setae and one pore-like sensillum (gFR2). Two setae (FR9 and FR10) and one pore-like sensillum (FR14) situated ...
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... (Figs. 25A, 26A). Frontal lines slightly lyriform. Nasale serrate with one tooth on each side. Right epistomal lobe projecting further than nasale; left lobe weakly projecting, not reaching further than nasale; lateral sides of anterior margin of epistome ...
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... (Fig. 26B) short, rather slender. Scape as long as pedicel. Pedicel with inner membranous area surrounded by sclerite on apical ...
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... Abdomen (Fig. 3). Abdominal segments with very small transverse setiferous projections on membranous parts. Segments 2 to 7 similar to segment 1 but anteromedian part with one small, oval dorsal sclerite on each side; lateral sclerites narrow, very small; segments 3 to 7 with spinose prolegs, spines of prolegs narrow, weakly curved towards apex (Fig. 28G). (Figs. 5, 25B): Segment 8 with moderately large, oval dorsal plate; the plate with a small emargination on median part of posterior edge; procercus incompletely sclerotised, with two long and one rather short setae. Second instar. Similar to third instar larva, more weakly sclerotised than third ...
Context 18
... 3). Abdominal segments with very small transverse setiferous projections on membranous parts. Segments 2 to 7 similar to segment 1 but anteromedian part with one small, oval dorsal sclerite on each side; lateral sclerites narrow, very small; segments 3 to 7 with spinose prolegs, spines of prolegs narrow, weakly curved towards apex (Fig. 28G). (Figs. 5, 25B): Segment 8 with moderately large, oval dorsal plate; the plate with a small emargination on median part of posterior edge; procercus incompletely sclerotised, with two long and one rather short setae. Second instar. Similar to third instar larva, more weakly sclerotised than third ...
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... Frontal lines more distinctly than those in third instar. Antenna (Fig. 24B) proportionally short, slender. Scape slightly shorter than pedicel. Maxilla (Figs. 24E-F): Maxillary palpomere 2 slightly wider than palpomere 3. First instar. Similar to second instar larva, more weakly sclerotised than second instar. Colour. Head and sclerotised parts brown to light ...
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... Antenna (Fig. 23A) proportionally short, stouter than that of second instar. Labium (Figs. 23F-G): Labial palpi slightly shorter than ...
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... (Fig. 26B): Antennal sensorium (SE1) proportionally smaller than in second instar. Habitat. Standing water. Larvae were found in very shallow water, on the muddy banks of a pond, or in very slowly fl owing water. They usually hide below the fallen leaves or in the ...
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... The larvae of this genus are similar to those of other genera of the Japanese Aci- docerini, but are distinguished from them by the following characters: (1) head capsule with scale-like setae (Fig. 36); (2) nasale with distinct teeth, not serrate or smooth (Figs. 36C, 42A); (3) each epistomal lobe with one or two stout, short scale-like setae and two short setae (e.g., Antenna 3-segmented, short, stout in fi rst instar (e.g., Fig. 30A) to rather slender in third instar (e.g., Fig. 33B). Flagellum the ...
Context 23
... atrium (Figs. 32B, 35B, 41B): Segment 8 with large, oval dorsal plate; posterior edge of plate projecting medially; procercus incompletely sclerotised, with one stout and two rather long setae. Segment 9 trilobed, partially sclerotised; median lobe with one small, incompletely sclerotised projection on each side; each lateral lobe with short, membranous ...
Context 24
... chaetotaxy of head. Frontale altogether with 44-46 sensilla (Figs. 29A, C, 36A, C). Central part with three pairs of sensilla divergent posteriad (FR1-3); FR1 rather long seta close to frontal line; FR2 pore-like; FR3 short seta situated more anteriorly than FR2. Three setae (FR5-7) situated posteriorly to antennal socket, FR6 between FR5 and FR7, FR7 close to inner margin of antennal socket. FR4 pore-like, ...
Context 25
... to the known species of the genus Helochares from Japan (all instars) 2 1. Secondary sensilla between PA6 and PA7 absent (Fig. 29A); mandible with two setae ( General morphology. Third instar. Colour. Head and sclerotised parts light yellowish brown; membranous parts milky white (Fig. ...
Context 26
... atrium (Fig. 32B): Segment 8 with large, oval dorsal plate; plate with four projections on median part of posterior edge, each median projections slightly bifi d, with two setae; lateral portion of dorsal plate with three setae each, median one long, remaining two rather long; procercus with one rather short, stout seta and two rather long setae. ...
Context 27
... Epistomal lobes somewhat asymmetrical; inner part of lobes strongly curved, lateral part slightly rounded (Fig. ...
Context 28
... chaetotaxy of head. Frontale altogether with 44 sensilla (Figs. 29A, C). FR2 situated more anteriorly and mesally than FR1. FR5 short seta; FR6 moderately long scale- like seta, close to FR7; FR7 moderately short. Nasale with a group of six stout, short setae and three pore-like sensilla (gFR1), the latter sensilla on lateral margin of median two large teeth. Each epistomal lobe with two short setae on ...
Context 29
... Nasale projecting slightly further than epistomal lobes (Fig. 42A). Epistomal lobes rounded, asymmetrical; right lobe projecting as far as left lobe. Antenna short, rather slender ( Maxilla (Figs. 42E-F): Maxillary palpomere 1 slightly shorter than palpomeres 3, palpomere 2 the shortest, palpomere 4 about as long as palpomere 1; palpomere 1 the ...
Context 31
... (Figs. 42C-D): Three to four secondary sensilla in medioposterior part of outer face of mandible, one close to MN1, remaining sensilla behind ...
Context 32
... Dorsal surface of head capsule without densely arranged, strong tooth-like cuticular projections (Figs. 54A, 58A, 62A). Frontal lines V-or U-shaped, converging towards base of head capsule (Figs. 54A, 58A, 62A); coronal line present. Epistomal lobes not or moderately extended anteriorly, setation of the lobes on both sides more or less the same (Figs. 52C, 55A, 56C, 60C, 62B). Shape of nasale variable (straight, weakly rounded, serrate, or with at ...
Context 33
... Dorsal surface of head capsule without densely arranged, strong tooth-like cuticular projections (Figs. 54A, 58A, 62A). Frontal lines V-or U-shaped, converging towards base of head capsule (Figs. 54A, 58A, 62A); coronal line present. Epistomal lobes not or moderately extended anteriorly, setation of the lobes on both sides more or less the same (Figs. 52C, 55A, 56C, 60C, 62B). Shape of nasale variable (straight, weakly rounded, serrate, or with at least two teeth, never with a single median tooth; Figs. 52C, 55A, 56C, 60C, 62B). Scape with ...
Context 34
... Dorsal surface of head capsule without densely arranged, strong tooth-like cuticular projections (Figs. 54A, 58A, 62A). Frontal lines V-or U-shaped, converging towards base of head capsule (Figs. 54A, 58A, 62A); coronal line present. Epistomal lobes not or moderately extended anteriorly, setation of the lobes on both sides more or less the same (Figs. 52C, 55A, 56C, 60C, 62B). Shape of nasale variable (straight, weakly rounded, serrate, or with at least two teeth, never with a single median tooth; Figs. 52C, 55A, 56C, 60C, 62B). Scape with numerous setae at least in the second and third instars (Figs. 55B, 59A-B, 63A) (all instars of Hydrophilus bear numerous setae on scape; Fig. 57A). ...
Context 35
... spinose prolegs. Median lobe of spiracular atrium simple, entire; prostyli reduced (Sternolophus) to long (Hydrochara and Hydrophilus) (Figs. 54B, 58B, 62C). General morphology. Third instar. Body rather thick (Figs. 2B, 51A). Colour. Head and sclerotised parts yellowish brown; non-sclerotised parts greyish white to light yellowish brown (e.g., Figs. ...
Context 36
... (Figs. 55H-I) well developed. Submentum fused to head capsule, large, subpenta- gonal, wider than mentum (e.g., Fig. 52B). Mentum subtrapezoidal in dorsal view, distinctly wider than prementum, dorsal surface bearing densely arranged, tiny cuticular projections on basal two-fi fths and sparsely arranged, small tooth-like cuticular projections; lateral surface serrate. Prementum subrectangular; dorsal surface of sclerite with one pair of small membranous ...
Context 37
... larger than lateral ones; procercus incompletely sclerotised, with one long and two short setae. Segment 9 trilobed, partially sclerotised; each lateral lobe with short, incompletely sclerotised acrocercus; urogomphi short, one-segmented; prostyli very long. First instar. Similar to third instar larva, more weakly sclerotised than second third (Fig. ...
Context 39
... chaetotaxy of head. Frontale altogether with 44 sensilla (Figs. 52A, C). Central part with three pairs of sensilla divergent posteriad; FR1 short seta, rather close to frontal line; FR2 pore-like, situated more anteriorly and more mesally, between FR1 and FR3; FR3 short and rather stout seta, situated more anteriorly and slightly more mesally than FR2. Three rather short setae (FR5-7) and one pore-like ...
Context 40
... (Figs. 52B, 53F-G): Submentum with two pairs of setae (LA1-2); LA1 moderately long, in each lateral corner, LA2 short, situated anteromesally to LA1 (Fig. 52B). Ventral surface of mentum with one pair of rather short setae (LA3) and pore-like sensilla (LA4) on distal part; LA3 behind LA4, LA4 close to distal margin. Dorsal surface of prementum with two pairs of pore-like sensilla (LA8-9); LA8 at midwidth of prementum close to basal margin; LA9 on small membranous area completely surrounded by ...
Context 41
... other Japanese genera of the Hydrophilini by their large body size; additional diagnostic characters are: (1) frontal lines U-shaped, forming a straight line in posterior part of the head (Fig. 58A); (2) nasale smooth (Fig. 56C); (3) epistomal lobes almost symmetrical, rounded (Fig. 56C); (4) General morphology. Third instar. Body rather thick (Fig. 2C). Colour. Brown to light yellowish brown, sclerotised parts darker (Fig. ...
Context 42
... diagnostic characters are: (1) frontal lines U-shaped, forming a straight line in posterior part of the head (Fig. 58A); (2) nasale smooth (Fig. 56C); (3) epistomal lobes almost symmetrical, rounded (Fig. 56C); (4) General morphology. Third instar. Body rather thick (Fig. 2C). Colour. Brown to light yellowish brown, sclerotised parts darker (Fig. ...
Context 43
... Membranous parts of thoracic segments with densely arranged small cuticular asperities and small stout setae. Prothorax wider than head capsule (Fig. 2C). Proscutum with two large, irregularly shaped subrectangular plates, each bearing numerous short to rather long setae; the plates closely attached to each other medially (Fig. 2C). Prosternum subtrapezoidal, rather narrow. Mesonotum with two sclerites on each side; anterior one on medioanterior part, small, narrow; posterior one on ...
Context 44
... Membranous parts of thoracic segments with densely arranged small cuticular asperities and small stout setae. Prothorax wider than head capsule (Fig. 2C). Proscutum with two large, irregularly shaped subrectangular plates, each bearing numerous short to rather long setae; the plates closely attached to each other medially (Fig. 2C). Prosternum subtrapezoidal, rather narrow. Mesonotum with two sclerites on each side; anterior one on medioanterior part, small, narrow; posterior one on median part, large but smaller than those on proscutum, subtriangular, bearing sparsely arranged setae of variable length. Metanotum with one sub- triangular sclerite on each side, ...
Context 45
... Abdomen 10-segmented, tapering posteriad (Fig. 2C); membranous area covered with densely arranged small cuticular asperities and small stout setae as those on membranous areas of thorax. Segments 1 to 7 similar in shape, with four small tubercles bearing long seta on posterior portion of each segment; segments 1 to 8 with one short setiferous projection on each side, projection on ...
Context 46
... Sternolophus Solier, 1834 (Figs. 2D-E, 51B, 60-63, 64D, 65D) Diagnosis. Larvae of this genus are distinguished from other Japanese Hydrophilini by the following combination of characters: (1) frontal lines V-shaped (Fig. 62A); (2) nasale with distinct teeth (Figs. 60C, 62B); (3) epistomal lobes rounded, projecting as far as or only slightly further than nasale (Figs. 60C, 62B); (4) mandibles symmetrical, with two large and one small inner teeth (Figs. 61B-C, 63C-D); (5) abdominal segments with rather short setiferous projections on each side (Fig. 51B). ...
Context 47
... Sternolophus Solier, 1834 (Figs. 2D-E, 51B, 60-63, 64D, 65D) Diagnosis. Larvae of this genus are distinguished from other Japanese Hydrophilini by the following combination of characters: (1) frontal lines V-shaped (Fig. 62A); (2) nasale with distinct teeth (Figs. 60C, 62B); (3) epistomal lobes rounded, projecting as far as or only slightly further than nasale (Figs. 60C, 62B); (4) mandibles symmetrical, with two large and one small inner teeth (Figs. 61B-C, 63C-D); (5) abdominal segments with rather short setiferous projections on each side (Fig. 51B). General morphology. Third instar. Body rather thick ...
Context 48
... 1834 (Figs. 2D-E, 51B, 60-63, 64D, 65D) Diagnosis. Larvae of this genus are distinguished from other Japanese Hydrophilini by the following combination of characters: (1) frontal lines V-shaped (Fig. 62A); (2) nasale with distinct teeth (Figs. 60C, 62B); (3) epistomal lobes rounded, projecting as far as or only slightly further than nasale (Figs. 60C, 62B); (4) mandibles symmetrical, with two large and one small inner teeth (Figs. 61B-C, 63C-D); (5) abdominal segments with rather short setiferous projections on each side (Fig. 51B). General morphology. Third instar. Body rather thick (Fig. 51B). Colour. Head and scle- rotised parts yellowish brown; non-sclerotised parts greyish white to ...
Context 49
... symmetrical, with two large and one small inner teeth (Figs. 61B-C, 63C-D); (5) abdominal segments with rather short setiferous projections on each side (Fig. 51B). General morphology. Third instar. Body rather thick (Fig. 51B). Colour. Head and scle- rotised parts yellowish brown; non-sclerotised parts greyish white to light yellowish brown (Figs. ...
Context 50
... Head capsule (Fig. 62A) subtrapezoidal, widest anteriorly. Frontal lines almost V-shaped, fused at base of head capsule, coronal line short. Surface of head capsule smooth. Six stemmata on each anterolateral portion of head capsule. Clypeolabrum (Fig. 62B) slightly asymmetrical. Nasale with fi ve teeth, four on right side more closely placed and projecting ...
Context 51
... Head capsule (Fig. 62A) subtrapezoidal, widest anteriorly. Frontal lines almost V-shaped, fused at base of head capsule, coronal line short. Surface of head capsule smooth. Six stemmata on each anterolateral portion of head capsule. Clypeolabrum (Fig. 62B) slightly asymmetrical. Nasale with fi ve teeth, four on right side more closely placed and projecting further than left one. Epistomal lobes almost symmetrical, weakly rounded, projecting as far as nasale; lateral part of anterior margin of epistomal lobes weakly ...
Context 52
... densely covered with fi ne pubes- cence on membranous parts; segments 1 to 7 similar in size and shape (Fig. 51B). Segment 1 with one small dorsal sclerite on anteromedian part on each side, and with small setiferous projections laterally; segments 2 to 7 similar to segment 1 but dorsal sclerites smaller than those on segment 1. Spiracular atrium (Fig. 62C): Segment 8 with large suboval dorsal plate, plate wider than long; posterior edge of segment 8 with four setiferous, stout and lobe-like almost membranous projections; procercus incompletely sclerotised, with three setae; urogomphi short, one seg- mented, with three setae, two long on median part, one very long on apex. Segment 9 ...
Context 53
... almost membranous projections; procercus incompletely sclerotised, with three setae; urogomphi short, one seg- mented, with three setae, two long on median part, one very long on apex. Segment 9 trilobed, partially sclerotised; each lateral lobe with small, incompletely sclerotised acrocercus. Second instar. Similar to third instar larva (Fig. 2D). Pubescence covering membranous parts of thoracic and abdominal segments sparser than in third instar. Swimming hairs of legs denser than in fi rst instar. First instar. Similar to third instar larva but more weakly ...
Context 54
... of the maxillae varies among taxa. Only Enochrus (Methydrus) japonicus bears stout secondary sensilla on the inner face of the stipes in the examined species of the Acidocerini (Figs. 24E, 26E, 66B). The remaining Acidocerini species examined bear WATTS 2002;TORRES et al. 2008TORRES et al. , 2011. The presence and absence of these secondary sensilla on the mentum may be used for the identifi cation of instars in the genus Enochrus (BYT- TEBIER & TORRES 2009) and Helochares (FERNÁNDEZ 2004). We confi rm that the number of ...
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Citations
... Larvae of Hydrochara are predators and adults are omnivorous. Adults of many species are highly phototropic at night (Minoshima & Hayashi 2011, Minoshima et al. 2012, Smetana 1980 (Przewoźny 2022). There are no additional reports of Chinese species of the genus since 1995 (Gentili et al. 1995). ...
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... Primary (present in first-instar larva) and secondary (arising in later instars) setae and pores were identified in the cephalic capsule and head appendages. Since only a third instar larva was studied, the primary chaetotaxy was interpreted and coded by comparison with Chaetarthria larvae and also with other hydrophilid genera for which the chaetotaxy is well known (e.g., Enochrus, Hydramara, Tropisternus, etc.) (Fikáček 2006;Fikáček et al. 2008Fikáček et al. , 2018Byttebier and Torres 2009;Minoshima and Hayashi 2011Torres et al. 2014;Rodriguez et al. 2015Rodriguez et al. , 2018Rodriguez et al. , 2020Archangelsky 2016;Archangelsky et al. 2016Archangelsky et al. , 2018Minoshima 2019). Homologies were established using the criterion of similarity of position (Wiley 1981). ...
The subfamily Chaetarthriinae includes morphologically distinct larvae that are adapted to a diversity of environments. Based on larval characters, cladistic analyses (maximum parsimony (MP) and Bayesian inference (BI) with homoplasy as a partitioning scheme)
were performed to test the monophyly of the subfamily and the relationships of the two tribes included in it: Chaetarthriini and Anacaenini. The chaetotaxy of a third instar larva Guyanobius adocetus is described and illustrated in detail, including morphometric characters. This larva is compared to those of the known larvae of the tribe Chaetarthriini belonging to the genus Chaetarthria, and Pseudorygmodus, Crenitis, and Crenitulus from Anacaenini. None of the unconstrained analyses recover Chaetarthriinae as monophyletic. Chaetarthria diverges in an early branch, probably due to a series of unique morphological modifications associated with a riparian lifestyle whereas Guyanobius appears closely related to Anacaenini. Two alternative positions of Guyanobius are revealed: (1) as sister of all Anacaenini (unconstrained MP) or (2) nested within Anacaenini as sister of Crenitis + Crenitulus (constrained MP and unconstrained BI). The genera Paracymus and Tormus (tribe Laccobiini) diverge as two successive branches subordinate to Chaetarthriinae (excluding Chaetarthria) in the unconstrained MP analysis. However, the support is rather weak, and the position of Paracymus and Tormus is an artifact produced by some homoplastic characters. In this regard, homoplasy partitioning resulted a useful technique to solve some artifacts generated by convergent morphologies.
... For Hokkaido, the nearest large island, 71 species of the studied families are known at the moment (Minoshima and Hayashi 2011;Minoshima 2016;Hoshina 2018;Kamite and Hayashi 2019;Nakajima 2020;Nakajima et al. 2020; Suzuki 2020; Species/ Subspecies List of Hokkaido Beetle 2020). This is only 1.4 times more than on Kunashir Island (47 species), while the areas of these islands differ 55 times. ...
... In addition, several genera, i.e. Oosternum, Hydrocassis, Agraphydrus, Chasmogenus, Neoriohelmis, Ordobrevia (Minoshima and Hayashi 2011;Minoshima 2016;Hoshina 2018;Kamite and Hayashi 2019;Suzuki 2020), and species, i.e. Enochrus japonicus (Sharp, 1873), E. umbratus (Sharp, 1884), Hydrobius pauper Sharp, 1884, Ochthebius hokkaidensis Jäch, 1998, O. nakanei Matsui, 1986, Zaitzeviaria gotoi (Nomura, 1959, etc. (Sharp 1884;Hebauer 1994;Jäch 1998aJäch , 1998bMinoshima and Hayashi 2011;Angus and Jia 2014;Suzuki 2020), known from Hokkaido are still not found on the Kuril Islands. ...
... Oosternum, Hydrocassis, Agraphydrus, Chasmogenus, Neoriohelmis, Ordobrevia (Minoshima and Hayashi 2011;Minoshima 2016;Hoshina 2018;Kamite and Hayashi 2019;Suzuki 2020), and species, i.e. Enochrus japonicus (Sharp, 1873), E. umbratus (Sharp, 1884), Hydrobius pauper Sharp, 1884, Ochthebius hokkaidensis Jäch, 1998, O. nakanei Matsui, 1986, Zaitzeviaria gotoi (Nomura, 1959, etc. (Sharp 1884;Hebauer 1994;Jäch 1998aJäch , 1998bMinoshima and Hayashi 2011;Angus and Jia 2014;Suzuki 2020), known from Hokkaido are still not found on the Kuril Islands. Genera absent in Kunashir are distributed mainly in the subtropical and tropical zones (Hansen 1999;Fiká cek et al. 2015) and are known in Hokkaido only from the southern part of the island. ...
The fauna of Kunashir Island and the islands of the Lesser Kuril Chain contains 47 species from 18 genera of Georissidae, Helophoridae, Hydrophilidae, Hydraenidae and Elmidae. Two species (Enochrus vilis (Sharp, 1884) and Ochthebius inermis Sharp, 1884) are recorded for Russia for the first time. Fifteen species are new to the fauna of Kunashir Island and the Lesser Kuriles. The article contains an annotated list of species, including the studied material and published records. The article is illustrated by photographs of habitats and species, maps of their distribution in Kunashir.
The relationships between the species richness on an island area and the features of the fauna of Kunashir in comparison with Hokkaido are discussed. The species richness of the studied Polyphaga families in Kunashir is almost 2/3 of the fauna of Hokkaido, while the island's area is 55 times smaller. The reason for the absence of large species of the genera Hydrochara and Hydrophilus in Kunashir is hypothesized to be a restriction of the northern range species boundaries by the July isotherm of +16°С.
... Larval knowledge for this tribe is fairly complete, with larvae known for eight of the nine genera (Tables 1, 2). Nonetheless, detailed chaetotaxic descriptions have been published for only five species included in two genera: Hydrobius fuscipes (Linnaeus, 1758), Hydrobius pauper Sharp, 1884, Hydrocassis jengui Satȏ, 1998, Hydrocassis lacustris (Sharp, 1884 and Hydrocassis unicata Ji & Schödl, 1998(Fikáček, 2006Fikáček et al., 2008;Minoshima & Hayashi, 2011a, b, 2012. Detailed morphological descriptions that do not include chaetotaxy are known for a number of species (Table 2). ...
... Larvae of Ametor scabrosus (Horn, 1873) and Hybogralius hartmeyeri (Régimbart, 1908) were borrowed from previous studies (Archangelsky, 1997(Archangelsky, , 2008. Information on other species: Hydrobius fuscipes, Hydrobius pauper, Hydrocassis jengi, Hydrocassis lacustris, Hydrocassis unicata and the outgroup taxa were obtained from the literature (Fikáček, 2006;Fikáček et al., 2008Fikáček et al., , 2017Byttebier & Torres, 2009;Torres et al., 2011;Minoshima & Hayashi, 2011a, b, 2012Torres et al., 2014;Rodriguez et al., 2015;Archangelsky, 2016;Archangelsky et al., 2016;Rodriguez et al., 2018) or from unpublished material (Derallus Sharp, 1882). ...
Phylogenetic analyses testing the monophyly of the tribe Hydrobiusini and the relationships among its genera are performed based on a data matrix including characters of larval morphology and morphometrics, larval chaetotaxy and adult morphology, including eight of the nine hydrobiusine genera plus 15 outgroup taxa. The head chaetotaxy of six genera of the tribe Hydrobiusini is described (Ametor, Hybogralius, Hydramara, Limnohydrobius, Limnoxenus and Sperchopsis). Morphometric characters derived from the head capsule and mouthparts are included. All characters are illustrated in detail. The analyses performed on the above datasets and their combinations reveal the monophyly of the Hydrobiusini except for Hybogralius, and reconstruct the internal topology of the tribe, largely corresponding to results of previous molecular analyses. Hybogralius groups with genera having larvae adapted to underwater feeding in all analyses. The position of the genus Tritonus within the Laccobiini is questioned by our analyses, which suggest a closer relationship with the tribes Hydrophilini or Hydrobiusini. Larval characters are revealed as highly homoplastic, with chaetotaxic characters performing slightly worse than usual larval morphology. Nonetheless, they are phylogenetically informative and useful for testing phylogenetic hypotheses resulting from analyses of molecules or adult morphology. A key to larvae of the genera of the Hydrobiusini is presented.
... In particular, H. acuminatus larvae prefer to eat A. ollula; the larvae use their asymmetrical mandibles to crunch snail shells and eat the inner soft bodies of snails (Inoda et al., 2003). Asymmetrical mandibles are found in all larval stages (Minoshima & Hayashi, 2011). The thin shells of A. ollula without the operculum cannot fully protect their inner soft bodies from the snail-eating predators. ...
Freshwater molluscs have physical defences such as shells to protect their inner soft bodies from underwater predators. However, some predators have specialized mouthparts that can destroy the snail’s tough and/or spiral shells. Therefore, these snails could have evolved specific defences against their specialist predators. We observed the freshwater snail Austropeplea ollula (Pulmonata: Lymnaeidae) frequently climbing rice plants above the water in paddy fields in Shimane, central Japan. We also found the beetle larvae of Hydrophilus acuminatus (Coleoptera: Hydrophilidae), which are known as snail-eating specialists, in waters of the same paddy fields. We hypothesized that A. ollula climbs rice plants above the water to escape underwater predation by H. acuminatus and that the escape behaviour of snails may be specifically triggered by chemical cues from snail-eating specialists and/or killed conspecifics. To test both these hypotheses, we conducted laboratory experiments. The results demonstrated that chemical cues (e.g. body fluids) from killed conspecifics could trigger A. ollula to crawl above the waterline. Furthermore, chemical cues (e.g. scent and digestive enzymes) from H. acuminatus could promote the behaviour. Therefore, A. ollula can successfully escape from H. acuminatus by climbing the rice plants above the water.
... Japan (Honshu, ?Hokkaido). The record of this species from Hokkaido (Minoshima & Hayashi, 2011, 2012 based on the preimaginal stages requires confirmation. ...
... The record of H. pauper by Uéno et al. (1985) from Japan judging by the photo most likely refers to H. fuscipes. All instars of the larva of Hydrobius were described (as H. pauper) from South Hokkaido (Minoshima & Hayashi, 2011, 2012 but their species affiliation requires confirmation. At present there is no information published of any Hydrobius from Honshu since Sharp's description of H. pauper. ...
The little-known water scavenger beetle Hydrobius pauper Sharp, 1884 has only ever been recorded from Japan. Based on the type series, the species is redescribed and its diagnostic features are clarified. The lectotype of H. pauper is designated. This species is compared with other Eurasian representatives of the genus Hydrobius Leach, 1815. A key to all Eurasian species of the genus is given.
... Protocols of larval examination generally followed those of Minoshima andHayashi (2011) andMinoshima (2018). Observations were carried out using an MZ16 (Leica, Wetzlar, Germany) and Olympus BX50 microscope. ...
... . Known examples of differences in head morphology within a genus concern the symmetry of the mandibles in Enochrus and Cymbiodyta (Archangelsky 1997;Minoshima and Hayashi 2011;M. Fiká cek, unpubl. ...
The New Zealand endemic beetle genus Saphydrus Sharp, 1884 (Coleoptera:Hydrophilidae:Cylominae) is studied in order to understand its phylogenetic position, species-level systematics, biology and distribution, and to reveal reasons for its rarity. The first complete genus-level phylogeny of Cylominae based on two mitochondrial (cox1, 16S) and two nuclear genes (18S, 28S) covering 18 of 19 genera of the subfamily reveals Saphydrus as an isolated lineage situated in a clade with Cylorygmus (South America), Relictorygmus (South Africa) and Eurygmus (Australia). DNA is used to associate two larval morphotypes with Saphydrus: one of them represents the larvae of S. suffusus Sharp, 1884; the other, characterised by unique characters of the head and prothorax morphology, is revealed as sister but not closely related to Saphydrus. It is described here as Enigmahydrus, gen. nov. with a single species, E. larvalis, sp. nov., whose adult stage remains unknown. Saphydrus includes five species, two of which (S. moeldnerae, sp. nov. and S. tanemahuta, sp. nov.) are described as new. Larvae of Enigmahydrus larvalis and Saphydrus suffusus are described and illustrated in detail based on DNA-identified specimens. Candidate larvae for Saphydrus obesus Sharp, 1884 and S. tanemahuta are illustrated and diagnosed. Specimen data are used to evaluate the range, altitudinal distribution, seasonality and population dynamics over time for all species. Strongly seasonal occurrence of adults combined with other factors (winter occurrence in S. obesus, occurrence at high altitudes in S. tanemahuta) is hypothesised as the primary reason of the rarity for Saphydrus species. By contrast, Enigmahydrus larvalis underwent a strong decline in population number and size since the 1970s and is currently known from a single, locally limited population; we propose the ‘nationally threatened’ status for this species. http://zoobank.org/urn:lsid:zoobank.org:pub:28D87163-29E8-418C-9380-262D3038023A
... The genus Enochrus contains numerous groups of morphologically similar species and very widely distributed species (e.g., Hansen, 1999); these conditions create substantial challenges for taxonomic study of the group. Immature stages of approximately 10% of known Enochrus species have been described or illustrated so far (e.g., Archangelsky, 1997;Byttebier & Torres, 2009;Minoshima & Hayashi, 2011). ...
The status of two taxonomically problematic species, Enochrus (Methydrus) uniformis (Sharp, 1884) and E. (M.) vilis (Sharp, 1884), are studied. Enochrus vilis is affirmed as a distinct species and restored from synonymy of E. (M.) affinis (Thunberg, 1794). The lectotype of E. uniformis is designated. Enochrus uniformis and E. vilis are redescribed. Enochrus vilis exhibits geographical variation in body size and the shape of the median lobe of the aedeagus. Two morphologically differentiated populations of E. vilis (northern and southern populations) were detected in Japan. Genetic distance of the COI gene between the specimens collected from Hokkaido (northern population) and Yamaguchi Prefecture (southern population) is 1.67%. Occurrence of E. affinis in Japan is confirmed and diagnostic information of the species is provided.
... Morphological terminology follows Hansen and Richardson (1998) and Minoshima and Hayashi (2011) for general morphology; chaetotaxy follows Fikáček et al. (2008) and Byttebier and Torres (2009). Classification follows Short and Fikáček (2013) and Seidel et al. (2016). ...
... The reduction of teeth on the nasale is often associated with further modifications of mouthparts, i.e., asymmetry of nasale, mandibles and maxillae, and presence of an asymmetrical hypopharyngeal lobe (Archangelsky 1999;Fikáček et al. 2018a). The Psalitrus larva does not show such modifications, thereby resembling the larvae of the aquatic Cylominae and the majority of Acidocerinae (sister taxon of Cylominae + Sphaeridiinae) (e.g., Archangelsky 1997;Minoshima and Hayashi 2011). This outgroup comparison illustrates that the toothed nasale of larval Omicrini is a plesiomorphy as supposed by Short and Fikáček (2013), and a reduced nasale is an apomorphy that evolved independently in the Sphaeridiinae and the Cylominae. ...
... The reduction of larval legs is an evolutionary trend of terrestrial Sphaeridiinae, especially in the Megasternini + Sphaeridiini clade, in which the segments of legs are more or less reduced, appearing as a minute tubercle (Oosternum and some Cercyon) to minute two segments (some Cercyon and Armostus) or five-segmented but short, rod-like (Sphaeridium) (Archangelsky 1997(Archangelsky , 1999(Archangelsky , 2018Minoshima 2018). The presence of legs in Omicrini is a plesiomorphy as supposed by Short and Fikáček (2013) based on the fact that terrestrial and aquatic cylomine larvae and acidocerine larvae have well-developed legs (e.g., Archangelsky 1997;Minoshima and Hayashi 2011;Fikáček et al. 2014;Minoshima et al. 2018). This is the first detailed description of the larval chaetotaxy of Omicrini. ...
The larval morphology of the water scavenger beetle Psalitrus yamatensis Hoshina & Satô, 2005 is described based on a specimen collected from Fukuoka Prefecture, Kyushu, Japan. This is the first description of the larval morphology of the hydrophilid genus Psalitrus d’Orchymont, 1919, as well as the first description of larval chaetotaxy of the tribe Omicrini. Species-level identification of the larva was performed using DNA barcoding of a molecular marker: a 658 bp fragment of the mitochondrial cytochrome oxidase I. A description including chaetotaxy of head capsule and head appendages, diagnosis, and illustrations of the larva is provided. Psalitrus larvae can be distinguished from other known larvae of the tribe Omicrini by the morphology of the head and legs. The larva shares characters with other known larvae of Omicrini; potential plesiomorphies are shared with Cylominae and aquatic hydrophilids; some characters are also shared with larvae of Megasternini and Sphaeridiini.
... Photographs were taken using the Canon EOS 550D digital camera attached to the microscope. Morphological terminology of larvae generally follows Minoshima & Hayashi (2011); for the chaetotaxy of the larval head, we refer to Fikáček et al (2008) and Byttebier & Torres (2009). Since the larval morphology of the Megasternini seems very uniform, I am describing external morphology in detail, but in case of chaetotaxy, I compare the putative larva of Motonerus with that of Cercyon praetextatus (Say, 1825) described by Archangelsky (2016) and only mention differences. ...
Numerous new material of the genus Motonerus Hansen, 1989 (Coleoptera: Hydrophilidae: Sphaeridiinae) was examined over the past decade, resulting in the discovery of several undescribed species as well as new distributional records for most of the previously described species. Three species are here described as new: Motonerus explanatus sp. nov. (Panama), M. inca sp. nov. (Venezuela, Ecuador, Peru, Bolivia) and M. sofiae sp. nov. (Peru). New country records are provided for M. depressus Fikáček & Short (new for Venezuela, Ecuador, Peru and Bolivia), M. hanseni Fikáček & Short (new for Panama) and M. problematicus Fikáček & Short (new for Panama). An updated identification key and distributional maps are provided for all species, along with complete occurrence data in a DarwinCore formatted file. Potential distribution of the genus is modeled using the maximum entropy approach. Wing morphology is examined in detail, which revealed most species are macropterous, with M. andersoni Fikáček & Short being brachypterous, and M. apterus Fikáček & Short, M. oosternoides Fikáček & Short, and M. explanatus sp. nov. micropterous. The third instar of the putative larva of M. obscurus Hansen is briefly described based on larvae collected in association with adults.
