XYLETINUS (S. STR.) THIENEMANNI SP. NOV., A NEW SPECIES OF XYLETININAE (COLEOPTERA: PTINIDAE) FROM EOCENE BALTIC AMBER

Abstract

Third extinct species of the extant genus Xyletinus Latreille, 1809 is figured and described
from Baltic amber. A key to fossil species of Xyletinus is provided.

Full text

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Acta Biol. Univ. Daugavp. 19 (1) 2019
ISSN 1407 - 8953
XYLETINUS (S. STR.) THIENEMANNI SP. NOV., A NEW
SPECIES OF XYLETININAE (COLEOPTERA: PTINIDAE)
FROM EOCENE BALTIC AMBER
Vitalii I. Alekseev, Andris Bukejs
Alekseev V.I., Bukejs A. 2019. Xyletinus (s. str.) thienemanni sp. nov., a new species of
Xyletininae (Coleoptera: Ptinidae) from Eocene Baltic amber. Acta Biol. Univ. Daugavp., 19
(1): 31 – 35.
Third extinct species of the extant genus Xyletinus Latreille, 1809 is gured and described
from Baltic amber. A key to fossil species of Xyletinus is provided.
Key words: Coleoptera, new taxon, death-watch beetle, Cenozoic, Tertiary, fossil resin.
Vitalii I. Alekseev. Shirshov Institute of Oceanology, Russian Academy of Sciences, Nahimovskiy
prospekt 36, 117997 Moscow, Russia, E-mail: alekseew0802@yahoo.com, Kaliningrad
Regional Amber Museum, Marshal Vasilevskii square 1, Kaliningrad, 236016, Russia
Andris Bukejs. Institute of Life Sciences and Technologies, Daugavpils University, Vienības
13, LV-5401 Daugavpils, Latvia, E-mail: carabidae@inbox.lv
INTRODUCTION
The extant genus Xyletinus Latreille, 1809
is distributed mainly in the Holarctic Region
(Zahradník 2017) and includes six subgenera:
Calypterus Mulsant et Godart, 1859;
Evaniocerius Gottwald, 1983; Pseudocalypterus
Gottwald, 1977; Xeronthobius Morawitz, 1863;
Xyletinus Latreille, 1809; and Xyletomimus
Reitter, 1901. The largest subgenus (about 70
described extant and two fossil species) is the
nominative one.
The representatives of the genus Xyletinus
Latreille, 1809 were reported in Baltic amber
since beginning of 20th century (Klebs 1910)
and later (Hieke & Pietrzeniuk 1984, Zahradník
& Háva 2014). Two fossil species of this genus
have been described from Baltic amber until
now (Alekseev & Bukejs 2019).
In the year 2018, one of us (V.A.), examining
amber collection of Mr. Friedhelm Eichmann
(Hannover, Germany) found specimen of
Xyletinus, which was considered to be new
species. The new species is formally described
and gured in the current paper.
MATERIAL AND METHODS
The single specimen was examined during
this study. The amber with inclusion is
deposited in the private collection of Friedhelm
Eichmann (Hannover, Germany) [CFE] and
likely to be later deposited in the museum
of the Geological-Palaeontological Institute
[Geologisch-Paläontologisches Museum] of
Hamburg University, now: CeNak, Centre of
Natural History [Centrum für Naturkunde],
Germany. The piece was polished by hand only.
The measurements were made using an ocular

32
micrometer in a stereoscopic microscope. The
gures were edited using Adobe Photoshop
CS8. Illustration of antenna was based on free-
hand drawings made during examination of the
original specimens.
The following references were used for the
generic attribution and comparison with recent
taxa: Koer (1969), White (1973), Español
(1979), Gottwald (1983), Logvinovskij (1985),
Lundberg (1991), Toskina (2002, 2005, 2009,
2015), Arango & Young (2012), and Zahradník
(2017).
SYSTEMATIC
PALAEOENTOMOLOGY
Family Ptinidae Latreille, 1802
Subfamily Xyletininae Gistel, 1856
Tribe Xyletinini Gistel, 1856
Genus Xyletinus Latreille, 1809
Subgenus Xyletinus Latreille, 1809
X. (s. str.) thienemanni sp. nov.
(Figs 1–3)
Material examined. Holotype: No. 779 [CFE].
Adult, sex unknown. The complete beetle
inclusion is preserved in a small polished piece
of transparent amber with a yellow shade and
with approximate dimensions 24×15×4 mm
without any further xation. Right side of thorax
and head of the specimen are partially obscured
by “milky” opacity. Syninclusions: two stellate
fagacean trichomes.
Type horizon. Baltic Amber, Upper or mid-
Eocene.
Type locality. The Samland (Sambian)
peninsula, the Kaliningrad region, Russia.
Description. Total body length 2.47 mm;
elytra length 1.9 mm, maximum combined
width of elytra 1.25 mm; pronotum length
0.57 mm, pronotum maximum width 1.14 mm.
Body elongate, subparallel, convex dorsally;
pubescence homogenous, ne, moderately
dense, semirecumbent; appear unicolorous dark
(as preserved).
Head hypognathous, turned downwards and not
visible in dorsal view; double punctured: with
very ne, uniformly dispersed punctures and
with additional larger, irregular, moderately
dense punctures (distance between punctures
about 0.5–1.5× diameter of one puncture);
frons evenly at, without carina, with shallow
impression anteriorly. Compound eyes
relatively small, rounded, slightly convex,
entire, with small distinct facets, without
ommatidial setae; widely separated, frontal
distance between compound eyes nearly equal
to 3.0× transverse diameter of one eye. Antennae
11-segmented, serrate, reaching elytral base;
antennomeres 1–2 elongate and rounded; scape
widest; antennomere 3 as long as antennomere
4, narrowly triangular; antennomeres 4–8
almost equilaterally triangular, antennomere 9
elongate triangular, antennomere 10 elongate;
antennomere 11 elongate, about 3.0× as long
as wide. Relative length ratios of antennomeres
equal to 2.0–1.5–1.0–1.0–0.9–0.9–1.0–1.0–
1.5–1.5–2.1. Terminal labial palpomere
dilated apically, triangular. Terminal maxillary
palpomere triangular, dilated apically, with
semicirculary concave distal margin, forming
acute triangular angles.
Pronotum convex, margined, nely pubescent,
transverse, 2× as wide as long, widest before the
middle; punctured like head, larger punctures
denser and almost rugose laterally, and sparser
medially. Anterior pronotal angles acute and
triangular; posterior pronotal angles widely
rounded and barely marked. Lateral margins not
visible in dorsal view.
Scutellar shield rounded, semicircular.
Elytra moderately short, elongate, 1.5× as long
as wide, with distinct humeri, longitudinally
striate. Striae with regular distinct round
punctures laterally, and without separate
punctation on disc and apex. Elytral intervals
slightly convex, pubescent. Interval pubescence
semierect, curved, arranged in rows and directed
backwards. Metathoracic wings not apparent.
Metaventrite without excavation for reception
of mesothoracic legs.
Alekseev V.I., Bukejs A.

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Figs 1–3. Xyletinus thienemanni sp. nov., holotype, No. 779 [CFE]: 1 – habitus, ventro-lateral
view (scale bar represens 0.5 mm); 2 – habitus, dorsal view (scale bar represents 0.5 mm); 3 –
reconstruction of antenna.
Legs slender, comparatively short, pentamerous.
Procoxae contiguous. Tarsus shorter than tibia.
Tarsomere 1 longest, as long as tarsomeres 2
and 3 combined. Meso- and metarsomeres 2–4
widened. Tarsal claws simple, thin, falcate,
symmetrical.
Abdomen with ve freely articulated, visible
ventrites, without excavation for reception of
metathoracic legs; nely and densely punctured,
distance between punctures approximately
0.5–1.0× diameter of one puncture; with very
ne and sparse setae. Relative length ratios of
Xyletinus (s. str.) thienemanni sp. nov., a new species of Xyletininae (Coleoptera: Ptinidae) from eocene baltic amber

34
ventrites 1–5 equal to 4–4–3–3–4.
Dierential diagnosis. The specimen No 779
is placed within the subfamily Xyletininae
of Ptinidae due to cylindrical body, convex
non-attened prothorax, margined pronotum,
hypognathous head, striate elytra with
semicircular projection laterally, pentamerous
tarsi with enlarged basal tarsomere and simple
claws, and elongate distal antennomeres. This
combination of characters diers the specimen
under study from the similar-looking small
representatives of Dasytidae or Cleridae, which
are also not extremely rare in Baltic amber.
The new fossil species is diagnosed as belonging
to the genus Xyletinus based on following
morphological characters: head deexed;
metathoracic ventrite and abdomen without
excavation for reception of mesothoracic
and metathoracic legs; antennae serrate; eyes
widely separate; elytra striate; three terminal
antennomeres not long in comparison with
preceding segments. The combination of the
following features allows the assignment of
Xyletinus thienemanni sp. nov. to the nominate
subgenus: eyes comparatively small, slightly
convex, not strongly prominent; frons wide;
terminal maxillary and labial palpomeres
triangular, dilated apically; tarsi short; and
elytral pubescence directed backwards.
Xyletinus (s. str.) thienemanni sp. nov.
resembling recent European species of the genus
and the subgenus, but diers in dual punctation
of head and pronotum, shape of antennomeres,
elytral strial punctures distinct laterally, frons
without carina, and shape of last maxillary
palpomere.
Xyletinus (s. str.) thienemanni sp. nov. diers
from two described Baltic amber congeners in
following characters:
(1) from Xyletinus (s. str.) besseli Alekseev
et Bukejs, 2019 in longer and more slender
antennae with antennomeres 10–11 not
transverse and dilated; in elytral striae with
distinct punctures laterally; in lesser body size
(2.47 mm in X. thienemanni sp. nov. in contrast
to 3.1 mm in X. besseli); in dual and denser
pronotal punctation;
(2) from Xyletinus (s. str.) barsevskisi Alekseev
et Bukejs, 2019 in antennomeres 2–10 not
serrate; in elytra striate on disc and elytral striae
with distinct punctures; in pronotum without
small, in dense granulation antero-laterally; in
pronotal anterior angles visible in dorsal view;
in lesser body size.
Derivatio nominis. Patronymic, this new
species is named after Johannes Thienemann
(1863 – 1938), German ornithologist and
a pioneer bird ringing who established the
Rossitten bird observatory on the Curonian Spit
(now Rybachy, Kaliningrad Region, Russia),
the world’s rst bird ringing station.
KEY TO FOSSIL SPECIES OF
XYLETINUS
(1) Elytral disc without distinct striae.
Antennomeres 2–10 serrate, triangular. Body
length 4.0 mm....................................................
......................X. barsevskisi Alekseev et Bukejs
– Elytral disc with distinct striae. Antennomere
2 not triangular. Body length lesser ................. 2
(2) Elytra with impunctate striae. Antennae
short, antennomeres 10–11 strongly
transverse and dilated. Body length 3.1 mm
…………….........X. besseli Alekseev et Bukejs
(3) Elytra with two lateral striae consisting
of distinct punctures. Antennomeres 10–11
elongate, longer than wide. Body length 2.47
mm ............................................. X. thienemanni
sp. nov.
ACKNOWLEDGEMENTS
The authors are grateful to Mr. Friedhelm
Eichmann (Hannover, Germany) for the loan of
the new for science fossil material. The study
of VIA was done with support of the state
assignment of IO RAS (Theme No. 0149-2019-
0013).
Alekseev V.I., Bukejs A.

35
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Received: 12.04.2019.
Accepted: 10.09.2019.
Xyletinus (s. str.) thienemanni sp. nov., a new species of Xyletininae (Coleoptera: Ptinidae) from eocene baltic amber