Lathrobium elongatiphallus Senda 2024, sp. nov.
Creators: name: Senda, Yoshihiro
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Lathrobium
Lathrobium elongatiphallus

description: Lathrobium elongatiphallus sp. nov.
(Figs. 1B, 3, 6)
http://zoobank.org/ urn:lsid:zoobank.org:act: CFBC56CE-983E-4CF9-B9B2-1C1E61C81409
Type material. Holotype: JAPAN: Honshu:, ♂, “ Dando-Uradani (930 m) | Shitara-cho, Aichi Pref. | [Honshu, JAPAN] | 5.x.1998 S. Nomura leg.” [printed on white label], “HOLOTYPE | Lathrobium elongatiphallus | sp. nov. | Des. Y. Senda, 2023” [printed on red label with black border]. (KUM). Paratypes: 1♂, 1♀, “ Shidara ”, Aichi Pref., 19.V.1982, M. Satô leg. (EUMJ); 1♀, Dando-uradani, Tamine, Shitara-chô, 2.XI.2019, T. Ôno leg. (pcYS).
Diagnosis. The new species is similar to Lathrobium kusamai Watanabe, 1999, but easily distinguishable from it by the following characteristics: 1) male abdominal sternite VIII with deep triangular posterior excision; 2) aedeagus very elongate, about 3.1 mm (while in L. kusamai: male abdominal sternite VIII with comparative shallow semielliptical posterior excision; aedeagus moderately elongate, about 1.5 mm).
Description. Colouration: Body black; antennae, mandibles, labrum, basisternum, meso- and metavantrite reddish brown; labial palpi, maxillae, legs and abdominal segment IX (apical part) and X brownish yellow; elytra somewhat dark reddish brown in sutural and apical area.
Male. Body elongate, subparallel-sided, slightly flattened dorsally, shining. Head subtrapezoid in dorsal view, lateral sides arcuate, widest at basal 1/3 of posterior part of eyes, HL/HW ≈ 0.9; surface with coarse setiferous punctures and coriaceous microsculpture; punctures of surface becoming slightly denser and less coarse in temporal area. Eyes small, about 0.3 times as long as temple, flat. Antennae moderate in length, AL/FBL ≈ 0.7; antennomere I widest at about half, dilated to widest point, thence gently contracted toward apex; antennomeres II constricted at the base; III–X almost moniliform; antennomere XI fusiform, pointed at apex; length/width ratio of each antennomere I to XI as follows: 2.8, 1.7, 2.4, 1.8, 1.7, 1.7, 1.7, 1.7, 1.6, 1.8, 2.4; relative lengths of antennomeres from base to apex from base to apex: 27.8: 11.1: 14.4: 12.2: 11.1: 11.1: 11.1: 11.1: 10.0: 10.0: 13.3, and relative widths: 18.0: 12.0: 11.0: 12.0: 12.0: 12.0: 12.0: 12.0: 11.0: 10.0: 10.0.
Pronotum oblong, widest at anterior 1/4, PL/PW ≈ 1.2, PL/HL ≈ 1.3, PW/HW ≈ 1.0, lateral sides feebly arcuate, but contracted from basal 1/3 to posterior corner; disc sparsely covered with coarse and setiferous shallow punctures except median smooth area; anterior margin feebly emarginate at middle, broadly rounded at corners; posterior margin feebly arcuate, rounded at corners. Scutellar shield with a few minute punctures, covered with indistinct microsculpture, sparsely covered with fine brownish pubescence. Elytra widest just before posterior corner, expanded weakly arcuately from base to posterior corner, EL/EW ≈ 0.6, EL/PL ≈ 0.6, EW/PW ≈ 1.0; disc covered with shallow punctures, sparsely covered with fine brownish pubescence. Hind wings absent. Legs rather slender, covered with golden pubescence; protarsomeres I–IV strongly dilated.
Abdomen covered with minute punctures, densely covered with brownish pubescence; sternite VI (Fig. 3A) without median depression, but covered with several short black setae at the middle of posteromarginal area; sternite VII (Fig. 3A) with triangular median depression, which is rather densely covered with short black setae, widely emarginate at the posterior margin; tergum VIII truncate at the posterior margin; sternite VIII (Fig. 3A) with median depression, which is densely covered with short black setae, with comparatively narrow and deep triangular posterior excision, lateral side of posterior excision weakly produced on posterior margin; tergum IX setigerous except on basal 1/4, with posterolateral projections as long as 1/5 of tergum IX and somewhat curved dorsally at apex, with pointed apex; sternite IX elongate, widest at basal 1/4, narrowed apically, setigerous in apical 2/5, with posterior margin arcuate; tergum X subtriangular, widest at basal corners, with few setae and pores, with posterior margin arcuate.
Aedeagus (Fig. 3B–D) elongate, 3.13 mm long, nearly symmetrical, sclerotised except membranous dorsal side; dorsal plate elongate and slender, symmetric, widest at apical 2/5, slightly curved ventrally in basal 3/5, emarginately dilated to widest point, thence gently contracted toward acute apex in dorsal view; ventral process long, lamellate, very gently and arcuately contracted to base of apical projection in ventral view, with longitudinal carina along midline in apical 4/5, curved ventrally in basal half, with apical projection, which is approximately 0.15 times as long as ventral process, widest at base, feebly contracted to middle, thence feebly and emarginately contracted toward acute apex in ventral view. Endophallus poorly developed, with simple internal sac, without teeth patch.
Female. Similar to male in general appearance. Length/width ratio of each antennomere I to XI as follows: 2.7, 1.7, 2.4, 2.0, 1.9, 1.9, 1.7, 1.7, 1.9, 1.8, 2.5; relative lengths of antennomeres from base to apex: 26.7: 11.1: 13.3: 11.1: 10.6: 10.6: 10.6: 10.6: 10.3: 10.0: 13.9, and relative widths: 18.0: 12.0: 10.0: 10.0: 10.0: 10.0: 11.0: 11.0: 10.0: 10.0: 10.0. HL/HW ≈ 0.8; AL/FBL ≈ 0.6; PL/PW ≈ 1.2; PL/HL ≈ 1.2; PW/HW ≈ 0.8; EL/EW ≈ 1.0; EL/PL ≈ 0.8; EW/PW ≈ 1.0.
Tergum VIII truncated at the posterior margin (Fig. 3E); sternite VIII (Fig. 3F) produced at the middle of posterior margin, which is arcuate and fringed with micropubescence; tergum IX (Fig. 3E & F) similar to male, but with thicker posterolateral projections; tergum X (Fig. 3E) similar to male. Gonocoxites (Fig. 3F): lateral gonocoxal plate (distal and proximal gonocoxites fused) elongate, setigerous, with few setae in apical area, with rounded apex.
Measurements. Male (n = 2)—BL: 8.70 & 9.00 mm; FBL: 4.30 & 4.27 mm; HL: 1.43 & 1.40 mm; HW: 1.58 & 1.60 mm; AL: 2.84 mm (paratype male lacking right antennomere III–XI and left antennomere V–XI); PL: 1.80 & 1.82 mm; PW: 1.54 & 1.55 mm; EL: 1.08 & 1.08 mm; EW: 1.53 & 1.62 mm.
Female (n = 1)—BL: 10.86 mm; FBL: 4.44 mm; HL: 1.39 mm; HW: 1.75 mm; AL: 2.74 mm; PL: 1.65 mm; PW: 1.39 mm; EL: 1.40 mm; EW: 1.43 mm.
Distribution. Japan: Central Honshu (northeastern area of Aichi Prefecture) (Fig. 6).
Etymology. The specific name is a combination of the Latin adjective “elongatus” and the noun “phallus”. Thus, it alludes to the elongate male aedeagus.
Comments. This new species belongs to the Lathrobium pollens group (sensu Senda, 2022) based on its characteristic states.
description: Published as part of Senda, Yoshihiro, 2024, Seven new species of the genus Lathrobium Gravenhorst (Coleoptera: Staphylinidae: Paederinae) from Central Honshu, Japan, with new distributional records, pp. 501-529 in Zootaxa 5403 (5) on pages 505-507, DOI: 10.11646/zootaxa.5403.5.1, http://zenodo.org/record/10562427