Batrisiella riparia Yin & Zeng, 2023

Yin, Zi-Wei & Zeng, Ting-Kai, 2023, Two new riparian Pselaphinae from Hubei, Central China (Coleoptera: taphylinidae), Zootaxa 5346 (3), pp. 317-324 : 318-320

Batrisiella riparia Yin & Zeng , sp. nov.

( Figs 1 , 3 )

Chinese common name: DZḳṁŧDzfim

Type material (67 exx.). Holotype: CHINA: J, ‘China: Hubei, Xianning City , Chongyang Co., Shuikeng Vill., 29°18′22″N, 114°10′23″E, 165 m, 16-17.vii.2023, riverbank, under stone, Ting-Kai Zeng, AE ẌṪOiǥŵDzffiṁṻ ḦAEñƃäŀ ’ ( SNUC) . Paratypes: CHINA: 37 JJ, 29 ♀♀, same collecting data as for holotype ( SNUC) .

Diagnosis. Male. Body length approximately 1.7–1.8 mm. Head subtruncate at base; vertex with curved transverse sulcus posterior to level of antennal tubercles, with long mediobasal carina, vertexal foveae moderately distinct and asetose; antenna relatively long, antennomeres each elongate, lacking modification. Discal stria of elytron extending posteriorly to approach posterior margin. Metafemur greatly swollen at apical 3/5 of dorsal margin. Abdomen dorsally with tergite 1 (IV) longer than 2–4 (V–VII) combined, simple. Aedeagus strongly asymmetric, ventral stalk of median lobe much narrower than dorsal lobe. Female. Body length approximately 1.7–1.8 mm, metafemur lacking modification, genital complex as in Figure 1I .

Description. Male. Body ( Fig. 1A ) length 1.73–1.79 mm; color reddish-brown, tarsi and mouthparts lighter in color. Dorsal surface of body covered with relatively short pubescence.

Head ( Fig. 1B ) subtruncate at base, much wider than long, length 0.37 mm, width across eyes 0.42 mm; vertex finely punctate, convex at middle, with moderately distinct, asetose and broadly separated vertexal foveae (dorsal tentorial pits), with short, curved transverse sulcus at level of posterior to antennal tubercles, mediobasal carina extending posteriorly to occipital constriction and anteriorly to sulcus (level of anterior margin of eyes), antennal tubercles moderately raised, surrounding area roughly punctate; frons coarsely punctate broadly and shallowly impressed medially, confluent with clypeus at middle, anterolaterally with thin, oblique carinae; clypeus with rough surface, its anterior margin carinate and moderately raised; ocular-mandibular carinae complete. Venter with tiny gular foveae (posterior tentorial pits) originating from shared small, transverse opening, with distinct median carina extending from opening anteriorly to mouthparts. Compound eyes greatly prominent, each composed of approximately 32 large ommatidia. Antenna 1.0 mm long, lacking modification; antennomere 1 thick and short, anterolateral margin with small hyaline, lamellar structure ( Fig. 1C ), antennomeres 2–7 each elongate, 7 longer than 6 and 8, 8 shortest, elongate, 9–11 enlarged, forming indistinct club, 10 as long as but broader than 9, 11 largest, slightly shorter than 9 and 10 combined (18:21), sub-fusiform, truncate at base.

Pronotum ( Fig. 1B ) slightly longer than wide, length 0.41–0.42 mm, width 0.40–0.41 mm, widest at middle; lateral margins rounded; disc moderately convex, finely punctate, with median longitudinal sulcus as long as semicircular lateral sulci in dorsal view; lacking median antebasal fovea, with complete, deep transverse antebasal sulcus connecting lateral antebasal foveae, with distinct antebasal spines; outer and inner pair of basolateral foveae small. Prosternum with anterior part slightly longer than coxal part, with small lateral procoxal foveae; hypomeral groove complete, with small lateral antebasal hypomeral impression; margin of coxal cavity thinly carinate.

Elytra much wider than long, length 0.57 mm, width 0.66–0.67 mm; each elytron with two large, widely separated basal foveae, lacking subbasal fovea; humeri roundly protuberant; discal striae long, slightly curved, extending from outer basal foveae to approximately apical 4/5 of elytral length; subhumeral foveae small, carinate marginal striae extending posteriorly from fovea to apex of elytra. Metathoracic wings fully developed.

Mesoventrite short, fully demarcated from metaventrite by oblique lateral carinae, with pair of admesal carinae; setose median mesoventral foveae broadly separated, lateral mesoventral foveae large and setose, forked internally. Metaventrite weakly convex adjacent to middle, with pairs of setose lateral mesocoxal and lateral metaventral foveae located lateral and posterior to coxal cavities, respectively, posterior margin with small and narrow split at middle.

Legs elongate; mesotibia with small spur at apex; metafemur ( Fig. 1D ) distinctly clavate, greatly swollen on dorsal side, forming two projections and with setose sulcate area between them, proximal area with dense, short sensory setae.

Abdomen slightly narrower than elytra, widest at basolateral margins of tergite 1 (IV), length 0.49–0.51 mm, width 0.61 mm; lacking modification. Tergite 1 (IV) in dorsal view longer than 2–4 (V–VII) combined; setose basal sulcus laterally ended at inner pair of basolateral foveae, with outer pair of basolateral foveae lateral to sulcus, discal carinae thin and short, indistinct; tergites 2 and 3 (V and VI) each short, lacking fovea, 4 (VII) as long as 2 and 3 combined along middle, with one pair of small basolateral foveae, 5 (VIII) semicircular, posterior margin broadly and roundly emarginate at middle. Sternite 2 (IV) with one pair of mediobasal foveae and one pair of large basolateral sockets, with one pair of short lateral carinae; midlength of sternite 2 as long as 3–5 (V–VII) combined, 3–5 each short, successively shorter, lacking fovea, 6 (VIII) greatly transverse, posterior margin evenly roundly curved, sternite 7 (IX) ( Fig. 1E ) suboval, apical half moderately sclerotized, basal half membranous, apical margin with few scattered long setae.

Aedeagus ( Fig. 1F–H ) 0.27 mm long, strongly asymmetric; median lobe with greatly expanded basal capsule and large, suboval foramen, with long, extended basoventral projection, ventral stalk of median lobe shorter and narrower than dorsal lobe, in lateral view sharply narrowing toward apex, in axial view twisted and narrowed at middle; dorsal lobe broadened apically, at apex bifurcated; parameres reduced to small, membranous structure located above foramen.

Female. Similar to male in external morphology; antenna slightly shorter; metafemur lacking modification; each compound eye composed of approximately 23 ommatidia; humeral prominence small, indistinct; metathoracic wings absent. Measurements (as for male): body length 1.72–1.81 mm; length/width of head 0.36–0.37/ 0.39–0.40 mm, pronotum 0.40–0.42/ 0.40 mm, elytra 0.50/ 0.64 mm; abdomen 0.50–0.52/ 0.59–0.60 mm; length of antenna 0.91–0.93 mm; maximum width of genital complex ( Fig. 1I ) 0.22 mm, genital plate slightly narrower than sternite 9, lateral arms narrowing distally.

Comparative notes. This species is morphologically most similar to the type species of Physomerinus Jeannel , P. septemfoveolatus (Schaufuss, L. W.) distributed in Vietnam and Thailand, by the greatly swollen male metafemora. They may be separated by the different shapes of the male femoral modification and the aedeagus. The metafemora of P. septemfoveolatus appear to have only one projection on the dorsal margin, and the surface declines distally following the projection. For the aedeagus of P. septemfoveolatus see Jeannel 1952: fig. 42.

Biology. Most individuals were collected under stones on the river bank, and a few were observed running around on sandy soil between grasses ( Fig. 3 ).

Distribution. Central China: Hubei.

Etymology. The name rîpârius (- a, - um) is a Latin adjective, meaning, “that inhabits the banks of rivers”, “riparian”, referring to the habitat where the species was collected.

Remarks. Without examining the aedeagus and lacking a closer look at the scapes, this species would be easily regarded as a member of Physomerinus due to the swollen male metafemora. This may be the reason why Jeannel (1952, 1958) created Physomerinus and removed other, unrelated species there when his generic concept of Pselaphinae was largely based on male features. The probable synonymy of Physomerinus with Batrisiella Raffray (pers. com. with S. Nomura, dated 2023-07-27), and placement of the other species of the genus will be dealt with separately.

Figures

FIGURE 1. Habitus and morphological details of Batrisiella riparia sp. nov., male. A. Dorsal habitus. B. Head and pronotum. C. Scape, arrow indicating lamellar structure at apicolateral corner. D. Metafemur. E. Sternite 7 (IX). F–H. Aedeagus, lateral (F), ventral (G), and axial (H). I. Female genital complex. Scale bars: 0.5 mm in A; 0.2 mm in B, D; 0.05 mm in C, E; 0.1 mm in F–I.

FIGURE 3. Collecting environment and habitat of Batrisiella riparia sp. nov. and Nipponobythus varicornis sp. nov.