Tribasodes kamedai Nomura

Jałoszyński, Paweł, Nomura, Shûhei & Tokushige, Norihide, 2024, Tribasodes kamedai Nomura is not a strictly cavernicolous species (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 5448 (2), pp. 261-272 : 262-270

Tribasodes kamedai Nomura

Tribasodes kamedai Nomura, 2012: 13 .

( Figs 1–26 )

Material examined: 3 ♂♂, Japan, Okinawa Prefecture, Okinawa Island, Kunigami-son, Mt. Nishime-dake , ~ 330 m, 26°48’03.2’’N, 128°16’42.6’’E, 18.02.2023, leg. P. Jałoszyński (cPJ) ; 2 ♂♂, 1 ♀, Okinawa Island, Kunigami-son, Uka , ~ 300 m, 26°48’05.5’’N, 128°15’55.6’’E, 18.02.2023, leg. P. Jałoszyński (cPJ) ; 1 ♂, Okinawa Island, Kunigami-son, Mt. Nishime-dake 13.3.2021, leg. N. Tokushige (cNT) ; 4 ♂♂, 1 ♀, Okinawa Island, Kunigami-son, Uka , 29.04.2020, 16.05.2020, 19.09.2020, 13.03.2021, leg. N. Tokushige (cNT) ; 1 ♂, Okinawa Island, Kunigami-son, Mt. Nekumachiji-dake , 06.06.2020, leg. N. Tokushige (cNT) ; 1 ♀, Okinawa Island, Ôgimi-son, Oshikawa-dô Cave , 220 m, 05.04.2023, leg. K. Sugaya ( NSMT) ; 1 ♀, same locality but 15.09.2023, leg. K. Sugaya ( NSMT) ; 3 ♂♂, Okinawa Island, Kunigami-son, Yona , 15.03.1985, leg. S. Nomura ( NSMT) ; 1 ♂, same locality but 05.03.1988, leg. T. Ueno ( NSMT) .

Revised diagnosis. Legs conspicuously long and slender ( Fig. 1 ); males with modified fore and hind legs: protibia ( Fig. 12 ) with subapical ventral rounded broadening, metatrochanter ( Figs 13, 14 ) with large distoventral arrowhead-shaped process, and metafemur ( Fig. 15 ) with dorsal group of curved erect setae near middle length; both sexes with large and approximately cordiform median convexity on metaventrite ( Fig. 9 ) distinctly impressed at middle; aedeagus in dorsal view ( Fig. 19 ) with subrectangular basal capsule longer than narrow distal process with triangular and pointed apex, in lateral view ( Fig. 21 ) distal process dorsally weakly convex and ventrally weakly concave, basal orifice slightly longer than distal process.

Redescription. Body of male ( Fig. 1 ) elongate and slender, strongly convex, moderately dark brown, setae slightly lighter than cuticle; BL 1.95–2.20 mm.

Head ( Figs 2 , 4–5 ) with subquadrate frons and vertex, flattened, broadest at eyes, HL 0.38–0.43 mm, HW 0.43–0.45 mm. Occipital constriction ( Fig. 4 ; occ) deep, slightly wider than width of vertex; vertex ( Fig. 4 ; vt) strongly transverse, with five carinae: weakly elevated but distinct vertexal carina ( Fig. 4 ; vc) posteriorly extending onto occiput and anteriorly onto frons; a pair of weakly marked short submedian carinae ( Fig. 4 ; smc) strongly converging anterad; and a pair of parallel supraocular carinae ( Fig. 4 ; soc) extending from posterolateral margin of vertex to posterior region of supraantennal tubercles. Dorsal tentorial pits ( Fig. 4 ; dtp) small, circular and asetose, situated at level of posterior margins of eyes. Tempora ( Fig. 4 ; tm) in dorsal view evenly rounded and strongly converging posterad. Frons ( Fig. 4 ; fr) strongly transverse and weakly impressed. Clypeus ( Fig. 4 ; cl) transverse, with broadly rounded and slightly elevated anterior margin. Supraantennal tubercles weakly elevated. Eyes ( Figs 2 , 4–5 ) small, strongly projecting from head silhouette and in lateral view round with weakly emarginate posterior margin, composed of 20–30 corneal lenses. Ocular-mandibular carina (i.e., lateral extension of elevated anterior clypeal margin forming lateral border of antennal fossa; Fig. 2 ; omc) strongly developed, its adocular end with ventrally-directed arm. Ventrally ( Fig. 5 ), head capsule with finely and transversely microsculptured subtrapezoidal gular plate ( Fig. 5 ; gp) laterally delimited by distinct gular sutures ( Fig. 5 ; gs); anteriorly gula delimited by posterior tentorial pits ( Fig. 5 ; ptp) situated in small common impression; genae ( Fig. 5 ; gen) weakly convex and along midline of head separated by narrow submental carina (i.e., vestigial posterior region of submentum laterally compressed by mesal expansions of genae; Fig. 5 ; smc); anterior region of submentum short and strongly transverse, forming weak smooth elevation just behind posterior mental region. Mouthparts generalized, as in most Batrisini , maxillary palps with palpomeres 4 fusiform and densely setose. Punctures fine and nearly evenly distributed on dorsal and ventral surfaces of anterior (exposed) region of head capsule, but surface somewhat coarse because of slightly elevated setal insertions, only large antennal fossae impunctate ( Fig. 2 ); setae on clypeus, frons and vertex moderately long and suberect, those on genae and tempora distinctly longer and more erect; antennal fossae and large anterolateral regions beneath ocular-mandibular carinae asetose.

Antennae ( Figs 1 , 6 ) nearly as long as head, pronotum and elytra combined, weakly thickening toward apices; AnL 1.35–1.46 mm; scape distinctly elongate, subcylindrical, in lateral view distinctly curved (convex ventrally and concave dorsally), with deep dorsal emargination, pedicel slightly broadening distad, distinctly elongate but clearly shorter and narrower than scape; antennomeres 3–7 each distinctly elongate, 8 indistinctly elongate, 9 and 10 clearly but weakly elongate, antennomere 11 longer than 9–10 combined, distinctly broader than 10, fusiform. Male secondary sexual characters on antennae include ventral flattening of antennomeres 8–10 and minute, barely discernible glandular tubercle ( Figs 6–7 ; gt) at base of antennomere 11. All antennomeres with uneven, slightly coarse surface and dense setae.

Prothorax ( Figs 2 , 4–5 ) in dorsal view cordiform. Pronotum ( Fig. 4 ) broadest near anterior third; PL 0.43– 0.45 mm, PW 0.45– 0.44–0.45 mm. Anterior margin weakly arcuate, delimited from lateral margins by shallow constriction; lateral margins strongly convex in anterior half, distinctly concave in posterior half; posterior corners nearly right-angled and blunt; posterior margin nearly straight, with weakly developed marginal carina on entire length. Median longitudinal sulcus ( Fig. 4 ; mls) broad and sharply marked, anteriorly obliterated just before anterior pronotal margin and posteriorly slightly deepened and connected with narrow median carina ( Fig. 4 ; mc) extending to posterior pronotal margin; pronotum with two pairs of lateral longitudinal carinae: inner one ( Fig. 4 ; ilc) extending from dorsal spines to anterior pronotal margin, and outer ones ( Fig. 4 ; olc) extending from lateral foveae to anterior margin. Base of pronotum with two pairs of barely discernible, small and shallow circular antebasal pits ( Fig. 4 ; abp). Pronotum with two pairs of spine-like processes: small lateral spines ( Fig. 4 ; ls) situated on lateral margins near middle of pronotal length, and larger dorsal spines ( Fig. 4 ; ds) on dorsoposterior region. Lateral foveae ( Fig. 4 ; laf) small but deep, asetose, situated between dorsal and lateral spines. Punctures on prothoracic dorsum as fine as those on head, surface similarly coarse because of elevated setal insertions; setae similar to those on frons and vertex, except for asetose median longitudinal sulcus and distinctly sparse vestiture on lateral regions anterior to lateral foveae.

Prosternum ( Fig. 5 ; pst) with basisternal (precoxal) region much longer than procoxal rests (which are composite structures combining posterior basisternal region and furcasternum situated behind profurcal invagination sites); notosternal sutures lacking; prosternum with one pair of foveae ( Fig. 5 , indicated by arrowheads) situated just in front of and slightly mesad procoxal cavity. Basisternal region posteriorly forming short and broadly subtriangular prosternal process not separating procoxae; surface of basisternal region densely covered with moderately long and suberect setae. Hypomeral ridge ( Fig. 2 ; hyr) developed along adcoxal margin of each hypomeron and demarcating narrow inner region of hypomeron; hypomeral groove ( Figs 2 , 5 ; hg) present and sharply marked, accentuated by inner ridge. Mesal regions of hypomera delimited by hypomeral grooves impunctate and asetose.

Elytra ( Figs 8 , 10 ) together subtrapezoidal with strongly rounded sides, broadest near posterior third; EL 0.63– 0.65 mm, EW 0.63–0.65 mm. Each elytron with complete adsutural sulcus ( Fig. 8 ; as), discal sulcus ( Fig. 8 ; ds) developed in slightly less than anterior 2/3, and with three small but distinct asetose circular basal foveae ( Fig. 8 ; bef). Posterolateral elytral corner obtuse-angled and broadly rounded; posterior elytral margin indistinctly concave. Punctures on elytra similar to those on pronotal disc but slightly sparser; setae sparse, short and suberect.

Mesoventrite ( Fig. 9 ; v 2 ) transverse, with lateral regions fully demarcated from metaventrite (i.e, mesometaventral border clearly marked; Fig. 10 ; msmtb). Mesanepisterna and anterior region of mesoventrite forming massive prepectus with distinct transverse groove along its anteroventral margin, posteriorly mesoventrite strongly and abruptly broadening, with lateral margins strongly diverging posterad and rounded. Mesoventral process ( Fig. 9 ; msvp) situated between anterior margins of mesocoxae, broadly subtriangular and posteriorly widely separated from anterior metaventral process. Prepectus covered with transverse microreticulation; posterolateral regions of mesoventrite smooth, impunctate and asetose; median postprepectal region covered with sparse suberect setae. Two pairs of setose foveal openings are situated on mesoventrite (indicated by arrowheads in Fig. 9 ): one pair ventrally and submedially just behind median region of prepectus; and one pair in lateroventral region of postprepectal mesoventrite.

Metaventrite ( Fig. 9 ; v 3 ) about twice as wide as long, weakly convex at sides, with large cordiform median convexity bearing large median impression, and, in some specimens minute and weakly elevated posteromedian tubercle. Anterior metaventral (intermesocoxal) process ( Fig. 9 ; amtvp) broadly subtriangular; metaventral intermetacoxal process ( Fig. 9 ; mtvp) broadly subtrapezoidal, divided medially by narrow and long indentation. Metaventrite with two pairs of setose foveal openings (indicated by arrowheads in Figs 9 , 10 ): just behind and laterad mesocoxal cavities; and just behind each mesocoxal rest at base of anterior metaventral process. Metaventrite finely punctate and covered with sparse and short setae denser on elevated submedian areas than on sides.

Legs ( Figs 1 , 5 , 9–15 ) conspicuously long and slender. Fore legs ( Fig. 5 , 10 , 12 ) with subconical coxa, small and short subtriangular trochanter, clavate femur, slightly sinuate tibia rapidly broadened in ventral subapical region to form broad rounded subtriangular convexity, and tarsus clearly shorter than half length of tibia, with tarsomere 1 short and largely hidden among apical tibial setae, and tarsomeres 2 and 3 each about 3 times as long as broad. Middle leg similar to fore leg but tibia nearly straight and lacking subapical broadening. Hind leg longest and similar to middle leg except for strongly modified trochanter ( Figs 10–11 , 13–14 ), which is elongate subtriangular with conspicuously large and arrowhead-shaped distoventral process; metafemur ( Fig. 15 ) near middle length with small dorsal group of erect and curved setae.

Abdomen ( Figs 8–10 ) shorter and narrower than elytra, AbL 0.45–0.53 mm, AbW 0.53–0.55 mm. Tergite IV ( Fig. 8 ) subrectangular, weakly broadening posterad, with two large setose foveal openings ( Fig. 8 , indicated with arrowhead) flanking anteromedian asetose and impunctate convexity delimited from surrounding areas in a stepwise manner; paratergites IV ( Fig. 8 ; pt) narrow and weakly narrowing posterad, each demarcated from disc by strong carina. Tergites V to VII together about as long as tergite IV, gradually becoming shorter, each with distinct lateral edge, but only tergite V with indistinctly demarcated paratergite. Tergite VIII ( Figs 9–10 , tVIII, Fig. 16 ) not visible in dorsal view, facing posteroventrad, subtrapezoidal with rounded margins and corners, its proximal region retracted into abdomen and clearly shorter than exposed distal region. Exposed surface of abdominal tergites with punctures and setae similar to those on elytra but slightly denser.

Sternite IV ( Figs 9–11 ; sIV) longer than each of V–VII separately, with large submedian setose foveal openings; sternites V–VIII gradually becoming shorter, each with small pair of submedian setose openings; sternite VIII ( Figs 9–10 ; sVIII, Fig. 17 ) with deeply bisinuate posterior margin; sternite IX ( Fig. 18 ) retracted into abdomen, asymmetrical, elongate with rounded subtriangular apex.All exposed sternites flattened at middle, covered with fine punctures and sparse nearly recumbent setae.

Aedeagus ( Figs 19–23 ) small, AeL 0.23 mm, with basal capsular region of median lobe stout, subrectangular and weakly elongate, distal process asymmetrical, elongate but shorter than basal capsule, with triangular and pointed apex, in lateral view ( Figs 21, 23 ) distal process weakly curved, with convex dorsal and concave ventral surface. Parameres (omitted in Figs 19–20 and 22 , one paramere shown in Figs 21, 23 ) membranous and nearly as long as basal capsule of median lobe, each with slightly more sclerotized apical region, both of similar shape and size.

Female. Externally differs from male in distinctly smaller eyes ( Fig. 3 ) composed of 15 or less ommatidia (see Discussion), unmodified antennomere 11, protibiae, metatrochanters, metafemora, less convex cordiform convexity on metaventrite, and antennae shorter in relation to body length. BL 1.90–2.32 mm; HL 0.38 mm, HW 0.40 mm, AnL 1.25–1.47 mm; PL 0.43 mm, PW 0.40 mm; EL 0.55 mm, EW 0.55 mm; AbdL 0.55 mm, AbdW 0.50 mm. Tergite VIII ( Fig. 24 ) subtrapezoidal, with exposed distal region subequal in length to retracted proximal region; sternite VIII ( Fig. 25 ) similar to that of male, with deeply bisinuate posterior margin; postabdominal sclerites ( Fig. 26 ) weakly sclerotized, symmetrical.

Distribution. Northern and central region of Okinawa-jima Island, Ryȗkyȗ Archipelago, Japan ( Fig. 27 ).

Figures

FIGURE 27. Distribution of Tribasodes kamedai Nomura.

FIGURES 1–3. Tribasodes kamedai Nomura. Dorsal habitus of male (1); head and prothorax in lateral view of male (2) and female (3). Abbreviations: ds, dorsal spine; hg, hypomeral groove; hyr, hypomeral ridge; laf, lateral fovea; ls, lateral spine; olc, outer longitudinal carina; omc, ocular-mandibular carina; soc, supraocular carina.

FIGURES 4–7. Tribasodes kamedai Nomura, male. Head, prothorax and elytral base in dorsal view (4); head, prothorax and mesothorax in ventral view (5, arrowheads indicate foveal openings); distal region of right antenna (6); glandular tubercle on antennomere 11 (7). Abbreviations: a9‒11, antennomere 9‒11; abp, antebasal pit; bef, basal elytral fovea; cl, clypeus; ds, dorsal spine; dtp, dorsal tentorial pit; fr, frons; gen, gena; gp, gular plate; gs, gular suture; gt, glandular tubercle; hg, hypomeral groove; ilc, inner longitudinal carina; laf, lateral fovea; ls, lateral spine; mc, median carina; mls, median longitudinal sulcus; occ, occipital constriction; olc, outer longitudinal carina; pst, prosternum; ptp, posterior tentorial pit; smc, submedian carina; smc, submental carina; smn, submentum; soc, supraantennal carina; tm, temple; vc, vertexal carina; vt, vertex.

FIGURES 8–9. Tribasodes kamedai Nomura, male. Elytra and abdomen in dorsal view (8); pterothorax and abdomen in ventral view (9). Arrowheads indicate foveal openings. Abbreviations: amtvp, anterior metaventral process; as, adsutural sulcus; bef, basal elytral fovea; ds, discal sulcus; msvp, mesoventral process; mtvp, metaventral intermetacoxal process; pt, paratergite; sIV‒VIII, sternite IV‒VIII; tIV‒VIII, tergite IV‒VIII; v2, mesoventrite; v3, metaventrite.

FIGURES 10–11. Tribasodes kamedai Nomura, male. Pterothorax and abdomen in lateral view (10; arrowheads indicate foveal openings.); metatrochanter in ventral view (11). Abbreviations: msmtb, meso-metaventral border; sIV‒VIII, sternite IV‒VIII; tIV‒tVIII, tergite IV‒VIII; tr3, metatrochanter.

FIGURES 12–15. Tribasodes kamedai Nomura, male. Protibia and protarsus in dorsal view (12); metatrochanter in ventral (13) and lateral (14) views; dorsomedian region of metafemur in lateral view (15). Abbreviations: cx3, metacoxa; fm3, metafemur; t1‒3, tarsomere 1‒3; tb1, protibia; tr3, metatrochanter.

FIGURES 16–26. Tribasodes kamedai Nomura. Male tergite VIII (16); male sternite VIII (17); male sternite IX (18); aedeagus in dorsal (19, 22) laterodorsal (20) and lateral (21, 23) views; female tergite VIII (24); female sternite VIII (25); female postabdominal sclerite (26).