Pachycraerus socotrensis, Lackner & Vienna, 2017

Lackner, Tomáš & Vienna, Pierpaolo, 2017, Histeridae of Socotra (Coleoptera: Histeroidea), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57, pp. 55-76 : 57-61

Pachycraerus socotrensis sp. nov.

(Figs 1–13)

Type material. HOLOTYPE: J, side-mounted on a triangular mounting card, genitalia extracted, dismembered and glued to the same mounting card as the specimen, with the following labels: ‘ YEMEN SOCOTRA / wadi Ayhaft / 12°36.5′N, 53°58.9′E / 200 m, 7-8.xi.2010 / P.Hlaváč lgt.[printed]’; followed by:‘ Pachycraerus / socotrensis / sp.nov . / HOLOTYPE / det. T. Lackner & / P. Vienna 2017 [red label, handwritten]’ ( NMPC) . ALLOTYPE: ♀, side-mounted on a triangular mounting card, genitalia extracted, dismembered and glued to the same mounting card as the specimen, with labels identical to those of the holotype ( NMPC) . PARATYPES: YEMEN: SOCOTRA: 1 J 2 ♀♀ and 3 unsexed spec., with labels identical to those of the holotype (2 spec. in PVCV; 1 J 2 ♀♀ and 1 spec. in TLCM) ; 1 J 2 ♀♀ and 3 unsexed spec., ‘Yemen, Soqotra Is. / 24–26/xi.2003 / WADI AYHAFT, 190m / N 12°36′38″E 53°58′49″ / ( GPS), David Král lgt. [printed]; followed by: ‘ YEMEN – SOQOTRA 2003 / Expedition; Jan Farkač, / Petr Kabátek & David Král [printed]’ (1 spec. in PVCV; 5 spec. in NMPC); 1 spec., ibid, but ‘ P. Kabátek lgt.’ ( TLCM); 1 spec., ‘Yemen, Soqotra Is., HOMHIL / protected area, 28.-29.xi.2003 / N 12°34′27″ E 54°18′32″E, 364 / m ( GPS), leg. P. Kabátek [printed]’; followed by: ‘ YEMEN – SOQOTRA / 2003 / Expedition; Jan Farkač, / Petr Kabátek & David Král [printed]’ ( NMPC); 2 spec., ‘Yemen, Soqotra Is.; / 5.xii.2003 / BA’A village env. / N 12°32′19″ E 54°10′41″ / 234 m ( GPS) ; Jan Farkač lgt. [printed] ’; followed by: ‘ YEMEN – SOQOTRA 2003 / Expedition ; Jan Farkač, / Petr Kabátek & David Král [printed]’ (1 spec. in NMPC; 1 spec. in PVCV) ; 1 spec., ‘ Yemen, Soqotra Is. , 27.xii.2003 / WADI DENEGHEN / N 12°36′56″ E 54°03′49″ / 85 m ( GPS), Jan Farkač lgt. [printed] ’; followed by: ‘ YEMEN – SOQOTRA 2003 / Expedition ; Jan Farkač , / Petr Kabátek & David Král [printed]’ ( NMPC) ; 1 spec., ‘ YEMEN, SOCOTRA ISLAND / DEIQUB cave 12.vi.2012 / cave & Croton socotranus + / Jatropha unicostata shrubland / 12°23.1′N, 54°00.9′E, 115 m [printed] ’; followed by: ‘ SOCOTRA expedition 2012 / J. Bezděk , J. Hájek, V. Hula / P. Kment, I. Malenovský, / J. Niedobová & L. Purchart leg. [printed]’ ( PVCV) ; 1 spec., ‘ YEMEN, SOCOTRA ISLAND / Allove area ,ALOOVE vill.env. / Jatropha unicostata shrubland / with Boswelia elongata trees / 19.-20.vi.2012 / 12°31.2’N, 54°07.4’E, 221 m [printed] ’; followed by: ‘ SOCOTRA expedition 2012 / J. Bezděk , J. Hájek, V. Hula / P. Kment, I. Malenovský, / J. Niedobová & L. Purchart leg. [printed]’ ( NMPC) ; 1 ♀, ‘ YEMEN, SOCOTRA Island / Aloove area , HASSAN vill. env. / 12°31.2’N, 54°07.4’E, 221 m / P. Hlaváč lgt., 9-10.xi.2010 [printed]’ ( TLCM) ; 1J and 1 unsexed spec., ‘ YEMEN, SOCOTRA ISLAND / SHEQ vill.env. 8.vi.2012 / Croton socotranus + Jatropha / unicostata shrubland / 12°39.7′N, 54°03.8′E, 15 m [printed] ’; followed by: ‘SO- COTRA expedition 2012 / J. Bezděk, J. Hájek , V. Hula / P. Kment, I. Malenovský, / J. Niedobová & L. Purchart leg. [printed]’ ( NMPC) ; 1 J, ‘ YEMEN, SOCOTRA Island, / Dixam plateau, / Firmihin (Dracaena forest), / 12°28.6′N, 54°01.1′E, 490 m, / L. Purchart leg., 15-16.xi.2010 [print- ed]’ ( NMPC) ; 1 J, ibid, but ‘ P. Hlaváč lgt.’ ( TLCM) ; 1 spec., ‘ YEMEN, SOCOTRA Island, Kesa env., 220-300 m / 12°39′37″N, 53°26′42″E / L. Purchart leg., 28.-29.i.2010 [printed]’ ( NMPC) ; 1 spec., ‘ YEMEN, Socotra Isl. / Diksam, 3. 1991 / Wranik lgt.’ ( TLCM) .

Description. Body (Fig. 1). PEL = 2.00–2.50

mm; APW = 0.60–0.90 mm; PPW = 1.10–1.50

mm; EW = 1.30–1.70 mm; EL = 1.40–1.60 mm,

elongate, slightly depressed, pronotum dark-

brown to black, elytra lighter, castaneous; legs and rest of body appendages reddish-brown.

Head ( Fig. 2 ) broad, finely punctuated, frontoclypeal region slightly depressed; supraorbital stria complete, well-impressed; frontal stria outwardly arcuate, anteriorly nearing epistomal margin. Eyes flattened, but well visible from above; labrum rectangular, approximately three Fig. 1. Pachycraerus socotrensis sp. nov., habitus in times as broad as long; mandibles stout, pointed dorsal view. apically; each mandible with small subapical tooth; maxillary palpi elongate, terminal palpiger approximately twice as long as penultimate; mentum, submentum as well as maxillary stipites and cardines densely setose. Antennal scape approximately as long as funicle; pedicel thickened, approximately as long as two following antennomeres together; antennal club oval, depressed, intersegmental sutures vague. Pronotum approximately 1.3 times broader than long across median line, with microscopic punctation, punctures separated by several times their diameter, laterally larger scattered punctures appear intermingled with fine punctation. Lateral pronotal stria well developed laterally, absent behind head; along posterior pronotal margin present irregular row of deep ocellate punctures. Anterior pronotal angles acute; hypomeron asetose. Elytral epipleural stria thin, complete; marginal elytral stria double; humeral elytral stria very thin, forked apically. Internal subhumeral stria present on apical elytral half, almost attaining elytral apex; elytral striae 1–2 deeply impressed, almost complete, stopping short of elytral apex; stria 1 apically somewhat shorter than stria 2; elytral stria 3 represented on basal third by row of points, apically continues as deeply-impressed stria; dorsal elytral stria 4 present as short elytral fragment. Sutural elytral stria shortened on both basal and apical (approximate) fifths. Elytral disc with scattered microscopic punctation, along elytral apical sixth several scattered larger and deeper punctures appear.

Propygidium ( Fig. 5 ) with microscopic punctation intermingled with deep large punctures separated by twice to several times their diameter; pygidium in basal half with scattered punctures, otherwise almost glabrous.

Prosternum ( Fig. 3 ): prosternal lobe large, outwardly arcuate apically, covered with dense tiny punctation, punctures separated (roughly) by their diameter, intermingled with larger, deeper scattered punctures separated by several times their diameter. Carinal prosternal striae thin, subparallel, slightly divergent anteriorly; lateral prosternal striae costate, divergent anteriorly. Mesoventrite ( Fig. 3 ) glabrous; marginal mesoventral stria well impressed, straight. Meso- -metaventral suture vague, meso-metaventral stria absent. Metaventrite even, with scattered microscopic punctation; lateral metaventral stria straight, well impressed, almost reaching metacoxa. Lateral disc of metaventrite with very large and deep punctures separated by less than half their diameter; metanepisternum barely visible, covered with elytral epipleuron.

Abdominal ventrite I even, with scattered microscopic punctation becoming more prominent apically. Lateral stria of abdominal ventrite I slightly costate; laterad to it present another much finer shortened stria parallel to it.

Legs. Protibia ( Fig. 4 ): protibial spur prominent, straight; protarsal groove deep, straight; outer protibial margin with five triangular teeth topped by short denticle, teeth diminishing in size proximally. Mesotibia likewise with five triangular teeth topped by denticle, teeth growing in size distally. Metatibia slightly longer than mesotibia, with single tiny denticle medially followed by two more slightly larger denticles situated near tarsal insertion.

Male genitalia. Sternite VIII and tergite VIII ( Figs 6–8 ) fused; tergite X ( Fig. 9 ) wedged between divided tergite IX; tergite IX with basal ‘tails’; sternite IX (spiculum gastrale; Fig. 9 ) anteriorly inwardly arcuate, rounded basally. Parameres of aedeagus ( Fig. 11 ) fused almost along whole length; aedeagus tube-like, median lobe protruding apically ( Fig. 12 ).

Female genitalia (Fig. 13). Median sclerite small, heart-shaped; gonocoxite setose, dentate apically; gonostylus bisetose.

Variability. In some specimens the thin stria next to lateral stria of abdominal ventrite I can be absent, punctures of lateral disc of metaventrite can be sparser, elytral stria 3 can be intermittent and almost complete.

Differential diagnosis. This Socotran species cannot be incorporated into the key of DESBORDES (1922: 384) due to the presence of the following characters: cuticle dark brown to lustrous pitch-black, elytra with only two complete dorsal striae (although in several specimens dorsal elytral stria 3 is complete, see below); dorsal elytral stria 1 does not reach elytral apex. Based on these particular characters alone, this species occupies an isolated position within the genus Pachycraerus . However, several specimens (where dorsal elytral stria 3 is complete) would key out in the aforementioned key near P. laticeps Lewis, 1906 described from Tanzania (Kilimanjaro), but do not correspond with it due to smaller body size and more cylindrical body shape. The cylindrical body shape of the Socotran species resembles P. desidiosus Marseul, 1854 from tropical Africa and Saudi Arabia, yet there are many differences between these two taxa, apart from different body sizes, dorsal elytral striae (more complete in P. desidiosus ) and several other characters that separate the two species as well.

Comments. The genus Pachycraerus Marseul, 1854 , with 63 currently described species, is almost exclusively African in its distribution, with a single undescribed species collected from southern Oman ( MAZUR 2011; T. Lackner, unpublished data). Its taxonomy is in flux, and a comprehensive revision of this rather large genus is highly necessary. New genus for the Socotra Archipelago.

Etymology. Patronymic adjective, given after the Socotra archipelago.

Collection circumstances. Found under bark of various trees.

Distribution. Endemic to Socotra Island.

Figures

Figs 2–5. Details of Pachycraerus socotrensis sp. nov. 2 – head, dorsal view; 3 – mesoventrite and prosternum; 4 – protibia, ventral view; 5 – propygidium and pygidium.

Figs 6–12. Pachycraerus socotrensis sp. nov., male genitalia. 6 – sternite and tergite VIII, ventral view; 7 – ditto, dorsal view; 8 – ditto, lateral view; 9 – tergites IX–X, dorsal view, spiculum gastrale (sternite IX), ventral view; 10 – tergites IX–X and spiculum gastrale (sternite IX), lateral view; 11 – aedeagus, dorsal view; 12 – ditto, lateral view; 13 – female genitalia: gonocoxite and median sclerite, dorsal view.