Arthromelodes lianghongbini Zhang, Wei & Yin, 2024

Zhang, Yong-Qin, Wei, Guo-Hao & Yin, Zi-Wei, 2024, Two new species of ant-loving beetles (Coleoptera: Staphylinidae: Pselaphinae) from Jiulong National Wetland Park, China, Zootaxa 5406 (2), pp. 336-342 : 339-341

Arthromelodes lianghongbini Zhang, Wei & Yin , sp. nov.

( Figs 2 , 3 )

Chinese common name: 梁氏丽Dzm

Type material (56 exx.). HOLOTYPE: CHINA: ♂: ‘China: Zhejiang, Lishui, Jiulong National Wetland Park , 28°23′4.86″N, 119°49’29.15”E, 50 m, 23.ix.2023, fern leaves, Zhang, Wei, Ming & Jia leg. (浙江丽水九AE国NJ ae地公园)’ ( SNUC) . PARATYPES: CHINA: 25 ♂♂, 16 ♀♀, same collecting data as for holotype; 5 ♂♂, 4 ♀♀, same collecting data as for holotype, except ‘ 22.ix.2023 ’ (浙江丽水九AE国NJae地公园)’ ( SNUC) . 2 ♂♂, 3 ♀♀, ‘ China: Zhejiang, Lishui, Bihu To Hongyu Vill., Jiulong Wetland Park , 28°23’6”N, 119°49’29”E, 50 m, 2.vi.2023, riverbank, Z–W. Yin leg. (丽水九AEae地公园)’ (2 ♂♂, 2 ♀♀ in IZCAS, others in SNUC) .

Diagnosis. Male. Body length approximately 2.2 mm. Head sub-rectangular at base; vertex with transverse sulcus between antennal tubercles and long mediobasal carina, vertexal foveae large and asetose; antennae elongate, lacking distinct club, antennomere 11 largest. Pronotum with distinct median and lateral longitudinal sulci, with complete transverse antebasal sulcus. Discal striae of elytra extending posteriorly to approximately apical 4/5 of elytral length, humeri denticulate. Mesotrochanter with pencil-like protuberance on ventral margin, mesotibia with large apical spine. Metatrochanter with large, axe-like projection. Tergite 1 (IV) with large cavity in posterior half, lateral setiferous patches composed of short setae. Aedeagus strongly asymmetric; median lobe with relatively small basal capsule and broad ventral stalk; dorsal lobe narrowed near middle; parameres fused to broad membrane. Female. Body length approximately 2.2 mm, legs and abdomen lacking modifications, genitalia as in Fig. 2J .

Description. Male. Body ( Fig. 2A ) length 2.20–2.25 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface covered with long pubescence.

Head ( Fig. 2B ) sub-rectangular, rounded at base, much wider than long, length 0.44–0.45 mm, width across eyes 0.51– 0.50 mm; vertex finely punctate at middle, area anterior to eyes coarsely punctate, with large asetose vertexal foveae (dorsal tentorial pits) and curved transverse sulcus between antennal tubercles, distinct mediobasal carina extending from head base anteriorly to sulcus, antennal tubercles moderately raised; frons slightly impressed medially, confluent with clypeus; clypeus with carinate and moderately raised anterior margin, both frons and clypeus covered with distinct punctures; ocular-mandibular carinae complete, branched below eye, obliquely extended to ventral surface. Venter with tiny gular foveae (posterior tentorial pits) in single pit, with distinct median carina extending from pit anteriorly to mouthparts. Eyes moderately prominent, each composed of approximately 28–30 ommatidia. Antenna moderately elongate, length 0.99–1.00 mm; lacking distinct club; antennomere 1 thick, subcylindrical, 2 much smaller than 1, elongate, 3 slightly longer than 4, antennomeres 4, 6 and 8 small, of similar size, 5 and 7 slightly larger than 8, 9–11 each moderately enlarged, 11 largest, approximately as long as antennomeres 9 and 10 combined (1:1), sub-fusiform.

Pronotum ( Fig. 2B ) approximately as long as wide, length 0.48–0.49 mm, width 0.49–0.50 mm, widest at middle; lateral margins rounded, convergent basally, parallel in basal 1/5; disc moderately convex, finely punctate, with median longitudinal sulcus as long as semi-circular lateral sulci in dorsal view; lacking median antebasal fovea, with complete, transverse antebasal sulcus connecting lateral antebasal foveae; small outer and inner pair of basolateral foveae present. Prosternum with anterior part slightly longer than coxal part, with small lateral procoxal foveae; thick hypomeral grooves extending from base to middle of anterior part, antebasal portion impressed, hypomeral ridges close to coxal cavities.

Elytra much wider than long, length 0.65–0.67 mm, width 0.80–0.82 mm; roundly trapezoidal, dorsal surface with dense, long pubescence; each elytron with two large, asetose, basal foveae; discal striae extending from outer basal foveae posteriorly for 4/5 elytral length; humeri denticulate, subhumeral foveae present, carinate marginal striae extending from foveae to posterior margin of elytra. Metathoracic wings fully developed.

Mesoventrite short, demarcated from metaventrite by transverse carina; median mesoventral foveae widely separated, in shared transverse opening, lateral mesoventral foveae large and setose, forked, posterior pair of forks much broader than anterior pair; marginal striae complete. Metaventrite slightly prominent, weakly impressed at middle, with well-developed lateral mesocoxal and two lateral metaventral foveae; posterior margin with small and narrow split at middle.

Legs moderately elongate; foreleg simple; mesotrochanter ( Fig. 2C ) with pencil-like extension on ventral margin, apex of extension with thin tuft of setae; mesotibia with distinct, subtriangular apical spine; metatrochanter ( Fig. 2D ) with large, axe-like projection on ventral margin; each tarsus with one major and one reduced setiform pretarsal claw.

Abdomen widest at mesal margins of tergite 1 (IV), length 0.67–0.69 mm, width 0.71–0.73 mm. Tergite 1 (IV) ( Fig. 2E ) greatly modified, approximately three times as long as 2–4 (V–VII) combined; with large central cavity in posterior half, with oval median nodule at posterior margin of cavity, with three pairs (lateral, medial, anteromedial) of setose tufts inside cavity, with large setiferous patches lateral to the cavity, basal sulcus separated by mediobasal and large basolateral foveae, with short, thin triangular discal carinae; tergites 2 and 3 (V and VI) lacking foveae, 4 (VII) longer than 2 and 3 combined along middle, with one pair of basolateral foveae, tergite 5 (VIII) semicircular, transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with two mediobasal foveae, and two pairs of basolateral foveae in short sulci, with pair of short lateral carinae; midlength of sternites 3–5 (V–VII) short, lacking foveae, sternite 6 (VIII) transverse, posterior margin broadly and roundly prominent at middle; sternite 7 (IX) ( Fig. 2F ) with moderately sclerotized, rounded apex and few long setae along apical margin.

Aedeagus ( Fig. 2G, H ) 0.40 mm in length, dorso-ventrally asymmetric; median lobe with relatively small basal capsule and roundly triangular basal foramen, ventral stalk broad, trilobed, lateral lobes curved and longer than subtriangular one; dorsal lobe broadened near base, narrowing apically and with small hook-like structure near apex; parameres fused and reduced to ventral membrane.

Female. Similar to male in external morphology; legs and abdomen lacking spines/projections or modifications; each compound eye composed of approximately 28 ommatidia. Measurements (as for male): body length 2.16 mm; length/width of head 0.42–0.45/ 0.51 mm, pronotum 0.47–0.48/ 0.48–0.49 mm, elytra 0.61–0.63/ 0.78–0.79 mm; abdomen 0.64–0.66/ 0.70–0.74 mm; length of antenna 0.93–0.98 mm; genital complex ( Fig. 2I ) 0.30 mm wide, genital plate approximately as wide as sternite 7 (IX), lateral arms broadened through whole length.

Comparative notes. This species is morphologically similar to a number of congeners from Japan ( Nomura 1991; Jałoszyński 2023) and A. choui Yin from Taiwan ( Yin 2018) in sharing a similar abdominal cavity on male tergite 1 (IV); and these species may form a monophyletic complex. Arthromelodes lianghongbini sp. nov. may be easily separated by the unique, broad and trilobed median lobe of the aedeagus. Arthromelodes tokushigei Jałoszyński from Okinawa, Japan is a wingless species, and A. choui Yin of Taiwan has more elongate antennae, and a modified metaventrite of the male. The genital complex ( Jałoszyński 2023: fig. 41) of A. tokushigei has sternite 7 (IX) with a pair of long lateral extensions, and the genital plate is short, only about half as wide as sternite 7, with slender lateral arms.

Biology. All individuals were collected from sifted fern leaf samples along or near the riverbank ( Fig. 3 ).

Distribution. Eastern China: Zhejiang.

Etymology. This species is named in honor of Hong-Bin Liang, who led the project and provided various kinds of support during our field work.

Figures

FIGURE 2. Morphology of Arthromelodes lianghongbini sp. nov. (A–I Male. J. Female). A. Dorsal habitus. B. Head and pronotum. C. Mesotrochanter and mesofemur. D. Metatrochanter and metafemur. E. Tergite1(IV), showing abdominal modification. F. Sternite 7 (IX). G, H. Aedeagus, ventral (H), and lateral (I). I. Genital complex. Scale bars: 0.5 mm in A; 0.3 mm in B, D, E; 0.2 mm in C; 0.05 mm in F; 0.1 mm in G–I.

FIGURE 3. Habitat of Trisiniotus jiulong sp. nov. and Arthromelodes lianghongbini sp. nov. along (A) and near (B) riverbank.