Feabatrus, Zhang & Yin, 2023

Zhang, Wen-Xuan & Yin, Zi-Wei, 2023, Feabatrus gen. nov., a conspicuous new genus of Batrisitae from Myanmar and China (Coleoptera: Staphylinidae: Pselaphinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 63 (1), pp. 165-175 : 166-168

Feabatrus gen. nov.

Chinese common name: flümDz

Type species. Feabatrus myanmarensis sp. nov., here designated.

Diagnosis. Body large-sized, ranging from 3.2–4.3 mm, with smooth, shiny elytra and abdomen. Head slightly wi- der than long, sub-rounded at base, with U-shaped sulcus connecting vertexal foveae, with long mediobasal carina, eyes prominent; antenna elongate, lacking modification. Pronotum with broad, laterally carinate median longitudinal sulcus and short, curved discal carinae, with three pairs of large antebasal, discal and marginal spines, with distinct median antebasal and inner and outer pair of basolateral foveae. Each elytron with three basal foveae, discal stria shallow and short, lacking subhumeral fovea. Abdomen elongate, constricted at base and narrowing apically; tergite 1 (IV) longest, with thin inner and thick and short outer marginal carinae; sternites 3–5 (V–VII) each with one pair of basolateral foveae. Aedeagus stout, endophallus armature composed of elongate and curved sclerite.

Description [figures based on a completely articulated male of F. leonardoi ]. Body length 3.2–4.3 mm; habitus elongate, dorsal surface of body covered with long, suberect setae; antenna relatively elongate, extending to more than half of elytral length when bent backward.

Head ( Figs 1A–C ) roundly rectangular, wider than long; lacking frontal rostrum, antennal tubercles weakly raised, posterior margin with distinct lateral postantennal pit ( Fig. 1A ; lpp); vertexal foveae (dorsal tentorial pits) ( Fig. 1A ; vf) relatively small, asetose, connected by reversed U-shaped sulcus, with long mediobasal ( Fig. 1A ; mbc) and thick lateral carinae; eyes prominent, ocular-mandibular carinae ( Fig. 1B ; omc) complete, extending to mandible. Venter with small gular foveae (posterior tentorial pits) ( Fig. 1C ; gf) originating from shared opening, thin gular carina ( Fig. 1C ; gc) extending from opening anteriorly to mouthparts; antenna with 11 antennomeres, club indistinct, loosely formed by apical three antennomeres; maxillary palpus with small palpomere 1, 2 basally pedunculate and broad at apex, 3 subtriangular, 4 fusiform, with small cone at apex.

Pronotum ( Figs 1D–F ) moderately transverse, lateral margin convergent anteriorly and constricted at basal 1/2, anterolateral margins with small denticles in front of middle, anterior and posterior margin slightly carinate; lateral sides with row of dense pubescence, with broad laterally carinate median and lateral longitudinal sulci ( Figs 1D, E ; mls, lls) and short mediobasal and curved discal carinae ( Fig. 1D ; mbc, dc), lateral antebasal foveae ( Figs 1D, E ; laf) asetose, with one median antebasal ( Fig. 1D ; maf) and two pairs of basolateral foveae ( Fig. 1D ; oblf, iblf), with large marginal, discal and antebasal spines, lacking transverse antebasal sulcus; with thin hypomeral carinae ( Fig. 1E ; hc) and small pit; prosternum with small lateral procoxal foveae ( Fig. 1F ; lpcf).

Elytra constricted and truncate at bases, each elytron with three basal foveae ( Fig. 1G ; bef), inner two close,lacking subbasal fovea; with shallow and short discal ( Fig. 1G ; ds) and complete sutural striae, lacking subhumeral fovea, slightly carinate marginal striae ( Fig. 1H ; ms) extended from approximately middle to posterior margin of elytra.

Mesoventrite with median foveae ( Fig. 2A ; mmsf) widely separated, in shared transverse opening, with large lateral mesoventral foveae ( Fig. 2A ; lmsf) forked internally; metaventrite with large, setose lateral coxal foveae ( Fig. 2A ; lmcf), lateral metaventral foveae ( Fig. 2A ; lmtf) separated, posterior margin with deep, narrow split in middle; metaventral coxae broadly separated.

Abdomen elongate; tergite 1 (IV) longest, with mediobasal and two pairs of basolateral foveae ( Fig. 2C ; mbf, blf), with thin inner marginal carinae, outer marginal carinae thick and short, with short, nodule-like discal carinae; tergites 2–4 (V–VII) each with one pair of basolateral foveae ( Fig. 2B ; blf) and thin lateral carinae; sternite 2 (IV) with one pair of mediobasal ( Fig. 2D ; mbf) and three pairs of basolateral foveae ( Fig. 2D ; blf), sternites 3–5 (V–VII) each with one pair of small basolateral foveae ( Fig. 2B ; blf).

Legs elongate, tarsomeres 2 and 3 subequal in length, with one major and one setiform claw.

Male has relatively longer antennae than female; trochanters and mesofemora with spine or projection on ventral margin; abdomen greatly elongate in at least one species; aedeagus asymmetric, stout, median lobe with large basal capsule, dorsal lobe short, flat, endophallus armature markedly long and curved. Female with long spines on tergites 2–4 (V–VII) in two species; tergite 5 (VIII) trapezoidal, flat or weakly arched, posterior margin weakly emarginate and with small nodule at middle; genital complex asymmetric, weakly sclerotized.

Comparative notes. Feabatrus gen. nov. belongs to a group of Oriental genera including Tribasodites Jeannel, 1960 , Coryphomodes Jeannel, 1960 , and those genera that possess spinose pronotal lateral margins and have three basal foveae on each elytron (= Tribasodes -group of NOMURA & IDRIS 2003). Feabatrus differs from all known Asian genera of this group in a combination of 1) large-sized body with long, suberect setae on dorsal surface and antennae; 2) pronotum with large marginal, discal and antebasal spines; 3) elytra each with a smooth disc, inner two basal foveae close, discal stria shallow, lacking subhumeral fovea; 4) sternites 3–5 (V–VII) with only one pair of small basolateral foveae; 5) constriction between elytra and abdomen distinct, and 6) flat, sub-trapezoidal female tergite 5 (VIII) in middle with a small nodule of the posterior margin.

Etymology. The generic name is a combination of the family name of Leonardo Fea, an Italian naturalist who collected the material of both new species described here, and a partially abbreviated name of Batrisus Aubé, 1833 , the type genus of the Batrisitae .

Comments on biology. The female genital complexes of all three species are slightly asymmetric, with membranous structures pressing genital plate to one side. For Batrisini this character state has not been known by us, and is postulated to be associated with an undocumented, specialized mating behavior of the species. Note that the female of two of the three Feabatrus species (see below) possesses long dorsal spines on tergites 2–4 (V–VII), and a similar condition can be found in a few species of the genera Intestinarius Kurbatov, 2007 (Batrisini) and Horniella Raffray, 1905 (Pselaphitae: Tyrini ), etc. The function of such spines in Pselaphinae is unknown, but a comparable case has been documented for the water strider Gerris incognitus Drake & Hottes, 1925 . ARNQVIST & ROWE (1995) provided experimental evidence that female abdominal spines of G. incognitus are used to thwart harassing males, while increasing female control over copulation. However, this ‘sexual-conflict’ hypothesis has never been tested for Pselaphinae , and further field observations or laboratory experiments are needed.

Figures

Fig. 1. Morphology of Feabatrus gen. nov.A–C – head, dorsal (A), lateral (B), and ventral (C); D–F – prothorax, dorsal (D), lateral (E), and ventral (F); G – right elytron; H – apical half of elytron, lateral. Abbreviations: bef – basal elytral foveae, dc – discal carina, ds – discal stria, gc – gular carina, gf – gular fovea, hc – hypomeral carina, iblf – inner basolateral fovea, laf – lateral antebasal fovea, lls – lateral longitudinal sulcus, lpcf – lateral procoxal fovea, lpp – lateral postantennal pits, maf – median antebasal fovea, mbc – mediobasal carina, mls – median longitudinal sulcus, ms – marginal stria, oblf – outer basolateral fovea, omc – ocular-mandibular carina, vf – vertexal fovea. Scale bars: 0.2 mm in A–F; 0.25 mm in G, H.

Fig. 2. Morphology of Feabatrus gen. nov. A – meso- and metaventrite; B–D – abdomen, lateral (B), dorsal (C), and ventral (D). Abbreviations: blf – basolateral fovea, lmcf – lateral mesocoxal fovea, lmsf – lateral mesoventral fovea, lmtf – lateral metaventral fovea, mbf – mediobasal fovea, mmsf – median mesoventral fovea, s1–5 – sternites 1–5 (III–VII), t1–4 – tergites 1–4 (IV–VII). Scale bars: 0.5 mm.