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A new species of Halacarsantia Wol, 1989 from Australia 1
A new species of Halacarsantia Wolff, 1989 (Crustacea,
Isopoda, Asellota, Santiidae) from Wistari Reef,
southern Great Barrier Reef, Australia
Michitaka Shimomura1,†, Niel L. Bruce2,‡
1 Kitakyushu Museum of Natural History and Human History, Kitakyushu 805-0071 Kitakyushu, Japan
2 Museum of Tropical Queensland, Queensland Museum and School of Marine and Tropical Biology, James
Cook University, 70-102 Flinders Street, Townsville, Australia 4810; Senior Research Fellow, Department of
Zoology, University of Johannesburg, Auckland Park, 2006 South Africa
† urn:lsid:zoobank.org:author:142F0F2F-875F-44EE-BC9C-DDFF1AF8DEDB
‡ urn:lsid:zoobank.org:author:9DA13F3D-AB3A-43E0-BF49-A71EBB8612D7
Corresponding author: Michitaka Shimomura (shimomura@kmnh.jp)
Academic editor: S. Brix| Received 3 November 2011| Accepted 9 February 2012|Published 2 March 2012
urn:lsid:zoobank.org:pub:37DACB80-384B-4D2F-9F39-0B70C8C5CFB1
Citation: Shimomura M, Bruce NL (2012) A new species of Halacarsantia Wol, 1989 (Crustacea, Isopoda, Asellota,
Santiidae) from Wistari Reef, southern Great Barrier Reef, Australia. ZooKeys 173: 1–9. doi: 10.3897/zookeys.173.2314
Abstract
Halacarsantia acuta sp. n. is described from Wistari Reef, Capricorn Group, southern Great Barrier Reef,
the rst record of the genus from Australia. e new species diers from its congeners in having antenna
agellum composed of 8 articles; epipod apically acute, without setae, broad maxilliped endite and pereo-
pod 1 basis with a short projection. A key to species of the genus is provided.
Keywords
Isopoda, Santiidae, Halacarsantia, coral reefs, eastern Australia
Introduction
e Santiidae is a small family of the Asellota with 28 species in ve genera (Schotte et
al. 2008 onwards). Species of Halacarsantia Wol, 1989 are tiny (0.62–0.85 mm) and
include six species, all from marine benthic habitats (Menzies and Miller 1955, Wol
1989, Wol and Brandt 2000, Müller 1992, Shimomura and Ariyama 2004). Two
ZooKeys 173: 1–9 (2012)
doi: 10.3897/zookeys.173.2314
www.zookeys.org
Copyright M. Shimomura, N. L. Bruce. This is an open access article distributed under the terms of the Creative Commons Attribution License 3.0
(CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Michitaka Shimomura & Niel L. Bruce / ZooKeys 173: 1–9 (2012)
2
species, Halacarsantia uniramea (Menzies & Miller, 1955) and H. kussakini Müller,
1992 has been so far described from the southern Pacic, from New Zealand and coral
reefs at Mooréa (Society Islands) respectively.
e marine asellote fauna of Australia is diverse in shallow and deep waters (Kensley
1982, Wilson 1989, Merrin and Poore 2003, Just and Wilson 2004), but remains partic-
ularly poorly documented in tropical Australia, with only three named species reported
from the Great Barrier Reef (Bruce 2009, Just and Wilson 2004, Kensley 1982). e
genus Halacarsantia has not previously been recorded from Australian waters, though
the genus is known from tropical and coral-reef habitats (e.g. Müller 1989, Wol 1989,
Wol and Brandt 2000). In the present paper, we report a new species of Halacarsantia
from the shallow coral-reef habitats of the Capricorn Group, southern Great Barrier Reef.
Material and methods
Collections of isopods were obtained by the CReefs program organized by the Australian
Institute of Marine Science (AIMS) in Heron Island in 2009. Pieces of coral rubble col-
lected by hand during SCUBA were washed in a bucket, and isopods were extracted by
decanting the suspension through a sieve with a pore size in 0.3 mm. All the specimens
obtained were xed and preserved in 95% ethanol. Each individual was dissected and pre-
pared for observation by a light microscope (Nikon E600). e total length as indicated in
“Material examined” was measured from the tip of the head to the end of the pleotelson.
e type specimens are deposited in the Museum of Tropical Queensland, Towns-
ville (MTQ).
Systematics
Family Santiidae Wilson, 1987
Halacarsantia Wol, 1989
http://species-id.net/wiki/Halacarsantia
Halacarsantia Wol, 1989: 184.
Type species. Halacarsantia justi Wol, 1989; by original designation.
Species included. H. colombiensis Wol & Brandt, 2000, Colombia; H. justi
Wol, 1989, Andaman Sea; H. kussakini Müller, 1992, Mooréa; H. ovata Shimomura
& Ariyama, 2004, Japan; H. setosa Shimomura & Ariyama, 2004, Japan; H. uniramea
(Menzies & Miller, 1955), New Zealand.
Diagnosis (modied from Wol 1989). Body depressed, lanceolate or ovate, wid-
est at pereonite 3, with robust setae on or near lateral margins of head, pereonites and
pleotelson. Head with large, broadly rounded, frontal lobe. Eye lobes obsolete or small.
A new species of Halacarsantia Wol, 1989 from Australia 3
No pleonite visible anterior to pleotelson. Second article of antennula with dorsolateral
projection; article 5 as long as two preceding equally sized articles combined, with aes-
thetasc. ird article of peduncle of antenna with outer projection, with robust seta.
Pereopods short, robust or slender, with robust setae, particularly on carpus. Pereopod
1 with two claws. Female operculum broader than long. Uropods uniramous.
Key to the species of Halacarsantia
1 Mandibular palp absent ..............................................................................2
– Mandibular palp present ............................................................................. 3
2 Body with many robust setae near lateral margin, without dorsal robust
setae ..................................................................................................H. justi
– Body with many robust setae on dorsum ....................................... H. setosa
3 Frontal lobe of head more than 0.6 times as wide as maximum width of head;
pleotelson broader than long; uropods stout ...............................................4
– Frontal lobe of head less than 0.3 times as wide as maximum width of head;
pleotelson narrower than long; uropods narrow ..........................................5
4 Coxal plates of pereonites 1, 2 and 4–7 dorsally invisible; eyes without bulg-
ing processes ...................................................................................H. ovata
– Coxal plates of all pereonites dorsally visible; eyes with bulging processes .....
............................................................................................H. colombiensis
5 Frontal lobe of head with 17 robust setae; antenna shorter than half length of
body; pereopods 5–7 broader than preceding pereopods; uropods stout........
................................................................................................ H. uniramea
– Frontal lobe of head with 6 robust setae; antenna longer than half length of
body; pereopods 5–7 similar to preceding pereopods; uropods slender ........6
6 Lateral margins of head each with 2 robust setae; antenna agellum com-
posed of 11 articles; maxilliped epipod apically blunt, with 2 setae ...............
................................................................................................ H. kussakini
– Lateral margins of head each with 3 robust setae; antenna agellum com-
posed of 8 articles; maxilliped epipod apically acute, without setae ...............
............................................................................................. H. acuta sp. n.
Halacarsantia acuta sp. n.
urn:lsid:zoobank.org:act:FAEAFDD4-6AE6-44BC-B733-B9274D16CF21
http://species-id.net/wiki/Halacarsantia_acuta
Figs 1–3
Material examined. Holotype. ♀ (0.83 mm, with 4 eggs), Wistari Reef, Great Barrier
Reef, Australia, 23 November 2009, 23°27.257’S, 151°52.840’E, northern side of reef,
rubble on bommie, 3 m, stn HI09-084F, coll. N. L. Bruce & K. Schnabel (MTQ
W34048).
Michitaka Shimomura & Niel L. Bruce / ZooKeys 173: 1–9 (2012)
4
Figure 1. Halacarsantia acuta sp. n. A–I holotype female: A habitus, dorsal B right antennula, ventral C
articles 1–3 of right antennula, dorsal D right antenna, ventral E left mandible, dorsal F right mandible,
dorsal G right maxilla 1, ventral H right maxilla 2, ventral I left maxilliped, dorsal. Scales = 100 μm.
A new species of Halacarsantia Wol, 1989 from Australia 5
Paratype. 1♀ (0.83 mm), same data as holotype (MTQ W31550).
Description of the holotype female. Body (Fig. 1A) 1.9 times as long as maxi-
mum width, with dark reddish brown pigment in patches. Head 1.4 times as broad
as long, narrower than pereonite 1, with 1 robust seta on anterior part of eyes; frontal
lobe broad and long, 0.32 times as wide as maximum width of head, with 6 long
robust setae on anterior margin; lateral margins of head, each with 1 slender and 3
robust setae; posterior margin of head convex. Eyes each with 7 ommatidia. Pereonites
laterally rounded; pereonites 1, 4 and 7 with 2 long robust setae near lateral margin on
each side; pereonite 2 with 2 short slender setae on each side of lateral margins and 2
long robust setae near lateral margin on each side; pereonites 3, 5 and 6 with 1 short
slender setae on each side of lateral margins and 3 robust setae near lateral margin on
each side. Pereonites 1 to 3 increasing in length; pereonites 3 and 4 subequal in length;
pereonites 5–7 subequal in length. Pereonites 1 to 3 increasing in width; pereonite 4
slightly narrower than pereonite 3; pereonites 4 to 7 decreasing in width. Coxal plates
dorsally visible on all pereonites, laterally rounded; coxal plate of pereonite 1 with 1
short seta; coxal plates of pereonites 2 and 3 each with 1 robust seta; coxal plates of
pereonites 4–6 each with 2 robust setae; coxal plate of pereonite 7 with 1 short seta.
Pleotelson (Figs 1A, 3E, 3F) pyriform, about 1.3 times as long as wide, with 7 robust
setae near dorsolateral margin on each side and 4 robust setae near ventrolateral margin
on each side.
Antennula (Figs 1B, 1C) composed of 5 articles. Article 1 broadest, with 1 simple
seta mediodistally and 1 broom seta laterodistally; article 2 slightly shorter than article
1, with 1 simple seta and 4 broom seta distally; article 3 with 1 simple seta mediodis-
tally; article 4 as long as article 3, without setae; article 5 twice as long as article 4, with
3 simple setae, 1 broom seta and 1 aesthetasc apically.
Antenna (Fig. 1D): peduncle composed of 4 short stout and 2 long slender articles,
and agellum of 8 short slender articles. Article 1 with 1 simple seta laterodistally;
article 2 without setae; article 3 with 1 simple seta mediodistally and 1 stout seta on
lateral protrusion; article 4 with 3 simple setae mediodistally; article 5 shorter than
articles 1–4 combined, with 1 simple and 1 biramous setae laterally and medially;
article 6 longer and slender than article 5, with 1 lateral and 1 medial simple setae, and
3 simple and 2 broom setae; agellar articles 1–7, each with 2 or 3 simple setae distally;
agellar article 8 with 6 simple setae apically.
Left mandible (Fig. 1E) palp article 1 with seta distally; article 2 longest, laterally
with 2 setae; article 3 as long as article 1, with 2 apical setae and few short setae; molar
process with 2 setae; lacinia mobilis with 2 teeth; setal row with 4 setae. Right mandible
(Fig. 1F) palp article 1 with seta distally, article 2 longest, laterally with 2 setae, article
3 as long as article 1, with 2 apical setae and few short setae; incisor with 4 cusps, setal
row with 4 setae; molar process stout, with 2 setae.
Maxilla 1 (Fig. 1G) with inner lobe bearing 4 apical and 2 medial setae; outer
lobe with 11 irregular and 1 simple setae distally. Maxilla 2 (Fig. 1H) with inner lobe
bearing 16 setae on margin; outer 2 lobes each with 4 apical setae.
Michitaka Shimomura & Niel L. Bruce / ZooKeys 173: 1–9 (2012)
6
Figure 2. Halacarsantia acuta sp. n. A–G holotype female: A right pereopod 1, medial B right pereopod
2, dorsal C right pereopod 3, dorsal D right pereopod 4, dorsal E right pereopod 5, dorsal F right
pereopod 6, dorsal G right pereopod 7, dorsal. Scale = 100 μm.
A new species of Halacarsantia Wol, 1989 from Australia 7
Maxilliped (Fig. 1I) palp slender: article 1 shortest, with 1 seta mediodistally;
article 2 about 1.9 times as long as article 1, with 1 medial seta; article 3 slightly longer
than article 2, with 1 seta laterodistally and 2 setae medially; article 4 as long as article
3, with 1 seta laterodistally and 2 setae medially; article 5 narrowest, with 2 slender and
2 stout setae apically; endite broad, bearing 2 simple setae ventrally, with 8 pectinate
setae distally, 1 simple and 2 fan-shaped setae on subdistal margin, and 2 coupling
hooks medially; epipod lanceolate, moderately broad, with acute apex.
Pereopod 1 (Fig. 2A): basis the longest article, with short projection ventrally, and
with 3 ventral and 1 dorsal setae; ischium 0.8 as long as basis, bearing 1 ventral and 1
dorsal setae; merus trapezoidal, with 4 ventral and 2 dorsal setae; carpus trapezoidal,
0.8 as long as merus, wider than merus, ventrally with 2 stout and 6 slender setae,
dorsally with 1 slender seta; propodus ovate, with 8 ventral and 3 dorsal setae; dactylus
shorter than propodus, with 1 curved unguis and 1 short accessory claw.
Pereopods 2–3 (Fig. 2B, C) subequal in shape and length; bases with 2–3 ventral
and 1 dorsal setae; ischia as long as bases, with 0–1 ventral and 2 dorsal setae; meri as
long as ischia, with 2 setae ventrally, 1–2 simple and 1 robust setae dorsodistally; carpi
Figure 3. Halacarsantia acuta sp. n. A–F holotype female: A operculum, ventral B right pleopod 3,
dorsal C right pleopod 4, ventral D right pleopod 5, ventral E pleotelson, ventral F pleotelson, lateral.
Scales = 100 μm.
Michitaka Shimomura & Niel L. Bruce / ZooKeys 173: 1–9 (2012)
8
shorter than meri, with 3–4 simple, 1 broom and 5–7 robust setae; propodi shorter
than carpi, with 3–5 simple and 1 robust setae; dactyli with 1 short setae, 1 curved
unguis and 1 curved accessory claw. Pereopods 4–6 (Fig. 2D–F) decreasing in length
posteriorly; bases with 2 short and 1 long setae ventrally, and with 0–1 short seta
dorsally; ischia with 0–1 short seta; meri with 2 short distal setae, and with 1–3 robust
setae and row of short setae dorsodistally; carpi with 2–3 robust setae ventrally and 3–6
robust setae distally; propodi with 1–2 short setae and 0–1 robust seta; dactyli with 1
short seta, 1 curved unguis and 1 curved accessory claw. Pereopod 7: basis shorter than
those of pereopods1–6, with 1 long and 2 short setae ventrally and 1 short seta dorsally;
ischium with 1 dorsal and 1 ventral setae; merus with 2 short setae ventrodistally and 3
robust setae and row of spinules dorsodistally; carpus with 4 robust setae ventrally and
1 robust seta dorsodistally; propodus with 2 short setae; dactylus with 1 short seta, 1
curved unguis and 1 curved accessory claw.
Operculum (Fig. 3A) 1.2 times as broad as long, with 2 lateral, 2 subapical setae,
and many ne marginal setae. Pleopod 3 (Fig. 3B) with endopod bearing 3 stout,
plumose setae distally; exopod narrower than endopod, bearing 1 lateral, 1 apical long
simple setae, and many ne setae on convex lateral margin. Pleopod 4 (Fig. 3C) with
ovate endopod; exopod uniramous, narrow, with 1 plumose seta distally, and many
ne setae on lateral margin. Pleopod 5 (Fig. 3D) ovate, uniramous, about 2.8 times as
long as broad, without setae.
Remarks. Halacarsantia acuta sp. n. may be distinguished from its congeners in
having long robust setae on the pereonites. e body shape of Halacarsantia acuta is
similar H. kussakini Müller, 1992 from the Society Islands, French Polynesia (type
locality), but H. acuta can be separated from H. kussakini by the (those of H. kussakini
in parentheses): 3 robust setae on each side of the head (2 setae); antenna agellum
composed of 8 articles (11 articles); maxilliped epipod apically acute, without setae
(apically blunt, with 2 slender setae); maxilliped endite broad (moderately narrow);
and pereopod 1 basis with a conspicuous short projection (without conspicuous
projections).
Etymology. e species is named after the apically acute maxilliped epipod.
Acknowledgements
Material was collected under the auspices of the CReefs project organized by the Aus-
tralian Institute of Marine Science (AIMS). e CReefs Australia Project is generously
sponsored by BHP Billiton in partnership with e Great Barrier Reef Foundation,
the Australian Institute of Marine Science and the Alfred P. Sloan Foundation; CReefs
is a eld program of the Census of Marine Life. I thank Julian Caley and Shawn Smith
(AIMS) for their excellent organization and eld support; NLB thanks Kareen Schna-
bel (NIWA, Wellington, New Zealand) for her excellent eld assistance while collect-
ing at the Capricorn Group reefs. MS thanks the Museum of Tropical Queensland for
supporting his 2010 research visit through a Visiting Curator award.
A new species of Halacarsantia Wol, 1989 from Australia 9
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