Songius brevisetus, Yin & Hu, 2023

Yin, Zi-Wei & Hu, Zheng-Kun, 2023, Two new sympatric species of Songius from Mount Fanjing, Southwest China (Coleoptera: Staphylinidae: Pselaphinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 63 (2), pp. 297-304 : 298-303

Songius brevisetus sp. nov.

Chinese common name: DZŁDzDȒƤ

( Figs 1 , 3 )

Type material (3 exx.). HOLOTYPE: CHINA: GUIZHOU: J, ‘ China: Guizhou, Tongren City, Mount Fanjing, Wanbaoyan to Huixiangping, 27°54′24″N, 108°42’9”E, 1930 m, 23.vii.2023, nest of Lasius sp. , Z-K Hu leg., ĒḅƜŊḮỄḖOişNj, Ȑữď※’ ( SNUC). PARATYPES: CHINA: GUIZHOU: 1 J, same data as that of holotype except ‘ 16.viii.2023 ’; 1♀, same data as that of holotype except ‘ 27°54′32″N, 108°41′58″E, 2020 m, 17.viii.2023 ’ (both in SNUC).

Diagnosis. Male. Habitus stout and compact, body length 2.7–2.8 mm; dorsal surface of body and antennae densely punctate and pubescent. Head with distinct cervical constriction, posterolateral margins bearing scattered and short row of thickened, stiff setae; eyes weakly protruding from head lateral profile; antennomeres moniliform, lacking modification. Pronotal disc broadly and moderately impressed along median longitudinal sulcus. Elytral disc moderately convex, humeri roundly prominent. Protrochanter spinose on both ventral and dorsal margin; mesotrochanter and mesofemur each with one protuberance on ventral margin, mesotibia at apex with small denticle; metacoxa with one round and metatrochanter with one blunt projection on ventral margin. Aedeagus asymmetric, median lobe with enlarged basal capsule and foramen, ventral lobe with short membranous apophysis on left side, right side of apical margin split to form two apically pointed branches; dorsal lobe composed of apically greatly curved sclerite with slight serration and membranous structures; endophallus armature absent; parameres reduced to membranous structure.

Female. Body length approximately 2.7 mm. Legs lacking spines or projections. Genital complex as in Fig. 1I .

Description. Male. Body ( Fig. 1A ) stout and compact, length 2.73–2.78 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body and antennae densely punctate and with dense and relatively short pubescence.

Head ( Fig. 1B ) sub-trapezoidal, approximately as long as wide, length 0.56–0.57 mm, maximum width across eyes 0.54–0.57 mm, with distinct cervical constriction at base; vertex weakly convex medially, with tiny, widely separated cuticle remnants of foveae (dorsal tentorial pits) ( Fig. 1B , indicated by arrowhead), with short and faint mediobasal carina; postocular margins evenly convergent, much longer than eyes, posteriorly with scattered thickened, stiff setae, posterolateral corners with short row of similar setae; frons broadening apically, broadest anterior to eyes, anteriorly largely fused with clypeus, area between barely raised antennal tubercles flat; clypeus moderately descending, densely punctate, its entire anterior margin moderately carinate and raised; ocular-mandibular carinae short due to closeness between eyes and mouthpart. Venter with granulate surface; gular region medially broadly and deeply impressed at base, small gular foveae (posterior tentorial pits) originating from shared large oval opening with ridged edge, with distinct median carina extending from opening anteriorly to mouthparts. Compound eyes weakly prominent, each composed of approximately 65 small ommatidia. Antenna moderately short, lacking modifications, length 1.49–1.50 mm, club formed by single terminal antennomere (11); antennomere 1 short and thick, subcylindrical, 2–10 moniliform, more-or-less transverse, 11 largest, distinctly longer than 9 and 10 combined (35:23), suboval, truncate at base.

Pronotum ( Fig. 1B ) slightly longer than wide, length 0.65–0.66 mm, width 0.62 mm, widest in approximately basal 1/3; lateral margin rounded at widest point and then convergent anteriorly and slightly less so posteriorly, anterior margin almost straight, weakly emarginate in middle, posterior margin evenly arched; disc broadly impressed along median longitudinal sulcus, sulcus followed anteriorly by short, thin carina, posteriorly by small, long oval impression and then short, thin mediobasal carina. Prosternum with anterior part in middle slightly longer than coxal part, with tiny, widely separated lateral procoxal foveae; thin hypomeral carinae complete, extending from posterior to anterior margin; margin of coxal cavity moderately carinate.

Elytra roundly quadrate, slightly wider than long, length 0.94 mm, width 1.15–1.17 mm, disc with distinct punctures; each elytron with three small, asetose basal foveae; lacking discal striae; humeri roundly prominent, lacking subhumeral foveae or marginal striae; posterolateral margins shortly truncate to form clefts. Metathoracic wings fully developed.

Mesoventrite short, fully demarcated from metaventrite by oblique carinae lateral to mesocoxal cavities; median mesoventral fovea absent, small lateral mesoventral foveae unforked internally, with markedly short, subtriangular mesoventral process, with complete marginal striae. Metaventrite moderately projected admesally, inclined towards middle, with well-developed lateral mesocoxal and two small lateral metaventral foveae, posterior margin with deep, narrow split in middle.

Legs moderately elongate, apical portions of ventral margins of femora with deep furrows to receive tibiae; protrochanter ( Fig. 1C ) with acute spine on both ventral and dorsal margins; mesotrochanter ( Fig. 1D ) with large tooth on ventral margin, mesofemur ( Fig. 1D ) with small ventral tubercle on basal 1/3, mesotibia with acute denticle at apex of mesal margin; metacoxa ( Fig. 1E ) with round ventral protuberance, metatrochanter ( Fig. 1E ) with short, curved and truncate projection on ventral margin.

Abdomen relatively short, rounded, widest at lateral margins of tergite 1 (IV), length 0.84–0.87 mm, width 1.12–1.13 mm. Tergite 1 (IV) slight longer than 2 (V) (33:25), with distinct basal sulcus and three pairs of basolateral foveae (inner two pairs much smaller than outer one), lacking discal carinae, marginal carinae short, extending to 1/4 tergal length; tergite 2 to 4 (VII) subequal in length in middle, 2 and 3 (VI) each with short, indistinct and 4 with complete lateral carinae; tergite 5 (VIII) roundly transverse, posterior margin broadly emarginate in middle. Sternite 2 (IV) in middle as long as 3–5 (V–VII) combined, with one pair of mediobasal and two pairs of basolateral foveae, lacking carinae, 3 and 4 (VI) subequal in length in middle, 5 shorter, 3–5 lacking foveae or carinae, 6 (VIII) greatly transverse, posterior margin sinuate, medially roundly convex, 7 (IX) ( Fig. 1F ) composed of pair of membranous lateral and suboval, moderately sclerotized median plates.

Aedeagus ( Figs 1G, H ) 0.56 mm long, stout, asymmetric; median lobe with enlarged basal capsule and foramen, ventral stalk broad, with thin, elongate membranous apophysis on left side (orientation as in Fig. 1H ), apical margin split on right side, forming two short, apically pointed branches; dorsal lobe elongate, apical part bent towards left and narrowing apically, apical margin slightly serrate at turning point; endophallus armature absent; parameres reduced to single membranous structure.

Female. Similar to male in external morphology; antenna slightly shorter; legs lacking modifications; each compound eye composed of approximately 52 ommatidia. Measurements (as for male): body length 2.73 mm; length/ width of head 0.58/ 0.53 mm, pronotum 0.64/ 0.62 mm, elytra 0.94/ 1.16 mm; abdomen 0.81/ 1.13 mm; length of antenna 1.32 mm; maximum width of genitalia ( Fig. 1I ) 0.31 mm. Comparative notes. The male of Songius brevisetus sp. nov. shares the setose body surface and antennae with S. lasiuohospes Yin, Li & Zhao, 2010 (Zhejiang, E China) and S. kiwi Yin & Li, 2015 (Guangxi, SW China), but differs from both in (1) protrochanters with a dorsal and a ventral spine (lacking spines in both S. lasiuohospes and S. kiwi ), (2) metatrochanters with an apically truncate and curved projection (with an apically acute, large blade-like spine in S. lasiuohospes , and a basally broad and apically narrowing spine in S. kiwi ), and (3) a much narrower apically curved part and a barely serrate apical margin of the dorsal lobe of the aedeagus. It further differs from S. kiwi in elytra having subparallel lateral margins (lateral margins distinctly divergent posteriorly in S. kiwi ). This species is more similar to S. lasiuohospes in the sub-parallel sides of the elytra and can be further separated from the latter by the small ventral tubercle of the mesofemora and small mesal denticle of the mesotibiae (with a wide, subtriangular ventral spine on mesofemora and a large, blade-like triangular spine at the apices of mesotibiae in S. lasiuohospes ). One indistinct aedeagal character of S. lasiuohospes , which was overlooked in previous studies, is the lateral side of the median lobe with a tiny protuberance bearing a few short setae at the apex (see YIN & LI 2015: figs 5A, B) which is absent in the new species and all other congeners.

Biology. All material was collected from Lasius ant colonies. The holotype male was collected together with a male of Songius hubenqii sp. nov. at an altitude of 1930 m.

Etymology. The epithet brevisetus (-a, -um) is a Latin adjective composed of the adjective brevis (short) and the noun sēta (hair), referring to the shortly and densely setose cuticle of this species.

Distribution. Southwest China: Guizhou ( Fig. 3 ).

Songius hubenqii sp. nov.

Chinese common name: ȐKDzDȒƤ

( Figs 2 , 3 ) Type material (9 exx.). HOLOTYPE: CHINA: GUIZHOU: J, ‘ China :

Guizhou, Tongren City, Mount Fanjing, Wanbaoyan to Huixiangping, 27°54′24″N, 108°42′9″E, 1930 m, 23.vii.2023, nest of Lasius sp. , Z-K Hu leg., ĒḅƜŊḮỄḖOişNj, Ȑữď※’ (SNUC). PARATYPES: CHINA: GUIZHOU: 1J, 4♀♀, same data as that of holotype except ‘ 28.vi.2023 ’; 1 J, same data as that of holotype except ‘ 06.viii.2023 ’; 1 J, same data as that of holotype except ‘ 16.viii.2023 ’; 1 ♀, same data as that of holotype except ‘ 27°54′32″N, 108°41′58″E, 2020 m, 17.viii.2023 ’. (SNUC).

Diagnosis. Male. Habitus stout and compact, body length 2.4–2.6 mm; dorsal surface of body and antennomeres 1–6 asetose, shiny, antennomeres 7–11 densely setose. Head with distinct cervical constriction, posterolateral margins bearing scattered and row of thickened, stiff setae; eyes barely protruding from head lateral profile; antennomeres moniliform, lacking modification. Pronotal disc broadly and moderately impressed along median longitudinal sulcus. Elytral disc moderately convex, humeri roundly prominent. Protrochanter lacking spine on ventral margin; mesotrochanter with small protuberance on ventral margin, mesofemur with long bristles on ventral margin; metacoxa simple, metatrochanter with blunt, apically curved projection on ventral margin. Aedeagus asymmetric, median lobe with enlarged basal capsule and foramen, ventral lobe with short membranous apophysis on left side, right side of apical margin split to form two apically pointed branches; dorsal lobe composed of apically greatly curved sclerite with smooth apical margin and membranous structures; endophallus armature absent; parameres reduced to membranous structure.

Female. Body length 2.5–2.6 mm. Legs lacking spines or projections; mesofemur lacking bristles on ventral margin. Genital complex as in Fig. 2I .

Description. Male. Body ( Fig. 2A ) stout and compact, length 2.40–2.60 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body and antennomeres 1–7 asetose, glabrous, antennomeres 8–11 with dense suberect setae.

Head ( Fig. 2B ) sub-trapezoidal, approximately as long as wide, length 0.56–0.58 mm, maximum width across postantennal area 0.52–0.54 mm, with distinct cervical constriction at base; vertex weakly convex medially, with tiny, widely separated cuticle remnants of foveae (dorsal tentorial pits) ( Fig. 2B , indicated by arrowhead), lacking mediobasal carina, apical area with pair of small admesal impressions; postocular margins evenly convergent, much longer than eyes, posteriorly with bunches of thickened stiff setae, posterolateral corners with short row of similar setae; frons broadening apically, broadest anterior to eyes, anteriorly fused with clypeus, area between barely raised antennal tubercles flat; clypeus smoothly descending, finely punctate, its entire anterior margin weakly carinate and raised; ocular-mandibular carinae short, due to closeness between eyes and mouthpart. Venter with rough surface; gular region medially broadly and deeply impressed at base, small gular foveae (posterior tentorial pits) originating from shared large oval opening with ridged edge, with distinct median carina extending from opening anteriorly to mouthparts. Compound eyes weakly prominent, each composed of approximately 45 small ommatidia.Antenna moderately short, lacking modifications, length 1.15–1.19 mm, club formed by single terminal antennomere (11); antennomere 1 short and thick, subcylindrical, 2–10 moniliform, distinctly transverse, 11 largest, distinctly longer than 9 and 10 combined (37:18), suboval, truncate at base.

Pronotum ( Fig. 2B ) approximately as long as wide, length 0.57–0.59 mm, width 0.61–0.62 mm, widest in approximately basal 1/3; lateral margin rounded at widest point and then convergent anteriorly and posteriorly, anterior margin almost straight, weakly emarginate in middle, posterior margin almost straight, weakly emarginate in middle; disc broadly impressed along thin median longitudinal sulcus, sulcus followed anteriorly by short, indistinct carina, posteriorly by small, long oval impression and then short, thin mediobasal carina. Prosternum with anterior part in middle as long as coxal part, with tiny, widely separated lateral procoxal foveae; thin hypomeral carinae complete, extending from posterior to anterior margin; margin of coxal cavity moderately carinate.

Elytra roundly quadrate, slightly wider than long, length 0.79–0.84 mm, width 1.08–1.10 mm, disc with indistinct, fine punctures; each elytron with three small, asetose basal foveae; lacking discal striae; humeri roundly prominent, lacking subhumeral foveae or marginal striae; posterolateral margins shortly truncate to form clefts. Metathoracic wings fully developed.

Mesoventrite short, fully demarcated from metaventrite by oblique carinae lateral to mesocoxal cavities; median mesoventral fovea tiny, small lateral mesoventral foveae unforked internally, with markedly short, subtriangular mesoventral process, with complete marginal striae. Metaventrite moderately projected admesally, inclined towards middle, with well-developed lateral mesocoxal and two small lateral metaventral foveae, posterior margin with deep, narrow split at middle.

Legs moderately elongate, apical portions of ventral margins of femora with deep furrows to receive tibiae; protrochanter ( Fig. 2C ) with acute spine on dorsal margin, ventral margin lacking spine; mesotrochanter ( Fig. 2D ) with short tooth on ventral margin, mesofemur ( Fig. 2D ) with long bristles along apical 2/3, mesotibia with small denticle at apex of mesal margin; metacoxa with blunt ventral protuberance, metatrochanter ( Fig. 2E ) with short, curved and truncate projection on ventral margin.

Abdomen relatively short, rounded, widest at lateral margins of tergite 1 (IV), length 0.79–0.80 mm, width 1.06–1.08 mm. Tergite 1 (IV) slight longer than 2 (V) (33:22), with distinct basal sulcus and one pair of small basolateral foveae, lacking discal carinae, marginal carinae markedly short, extending to 1/8 tergal length; tergite 3 (VI) shorter than 2 (V) and 4 (VII) in middle, 2 and 3 (VI) lacking and 4 with complete lateral carinae; tergite 5 (VIII) roundly transverse, posterior margin broadly emarginate in middle. Sternite 2 (IV) in middle slightly shorter than 3–5 (V–VII) combined, with one pair of mediobasal and two pairs of basolateral foveae, lacking carinae, 3 to 5 (VII) subequal in length in middle, lacking foveae or carinae, 6 (VIII) greatly transverse, posterior margin sinuate, medially roundly convex, 7 (IX) ( Fig. 2F ) composed of pair of membranous lateral and suboval, moderately sclerotized median plate.

Aedeagus ( Figs 2G, H ) 0.56 mm long, stout, asymmetric; median lobe with enlarged basal capsule and foramen, ventral stalk broad, with thin, elongate membranous apophysis on left side (orientation as in Fig. 2H ), apical margin split on right side, forming two relatively long, apically pointed branches; dorsal lobe elongate, apical part bent towards left and narrowing apically, apical margin smooth, lacking serration; endophallus armature absent; parameres reduced to single membranous structure.

Female. Similar to male in external morphology; antenna slightly shorter; legs lacking modifications; each compound eye composed of approximately 35 ommatidia. Measurements (as for male): body length 2.51–2.60 mm; length/width of head 0.56/ 0.53 mm, pronotum 0.58– 0.59/ 0.62 mm, elytra 0.82–0.86/ 1.09–1.10 mm; abdomen 0.77–0.82/ 1.09–1.11 mm; length of antenna 0.96–0.99 mm; maximum width of genitalia ( Fig. 2I ) 0.35 mm.

Comparative notes. The male of this species shares a shiny, glabrous cuticle with S. hlavaci . The new species differs in the eyes much less protruding laterally so that they are hardly visible dorsally, antennomeres 1–6 almost asetose, mesofemora with long bristles on the ventral margins, and apically curved portion of the dorsal lobe of aedeagus much narrower and with a smooth apical margin. In S. hlavaci , the antennomeres 1–6 are densely setose, the mesofemora lack bristles on the ventral margins, and the apical portion of the dorsal lobe of aedeagus is much broader and with a serrate apical margin.

Biology. All individuals were collected in nests of Lasius ants. One male was obtained together with S. brevisetus sp. nov. from the same colony.

Etymology. The species is named after Ben-Qi Hu, son of the junior author.

Distribution. Southwest China: Guizhou ( Fig. 3 ).

Figures

Fig. 1. Songius brevisetus sp. nov., male (A–H) and female (I). A – dorsal habitus; B – head and pronotum; C – protrochanter; D – mesotrochanter and mesofemur; E – metacoxa and metatrochanter; F – sternite 7 (IX); G, H – aedeagus, dorsal (G), and ventral (H); I – genital complex. Scale bars: 0.5 mm in A, B; 0.2 mm in C, E, G, H; 0.3 mm in D; 0.1 mm in F. I.

Fig. 3. Distribution and collecting environment of Songius. A – Map showing the distribution of five Songius species in China. B, C – General environment (A) and habitat (B) of S. brevisetus sp. nov. and S. hubenqii sp. nov. of Mount Fanjing, Guizhou, SW China.

Fig. 2.Songius hubenqii sp. nov., male (A–H) and female (I). A – dorsal habitus; B – head and pronotum; C – protrochanter; D – mesotrochanter and mesofemur; E – metatrochanter; F – sternite 7 (IX); G, H – aedeagus, dorsal (G), and ventral (H); I – genital complex. Scale bars: 0.5 mm in A, B; 0.2 mm in C, E, G, H; 0.3 mm in D; 0.1 mm in F. I.