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

description: Lathrobium minoccidentale sp. nov.
(Figs. 1E, 7, 8)
http://zoobank.org/ urn:lsid:zoobank.org:act: 153C6384-8DBD-4904-B727-02F80EEC820C
Type material. Holotype: JAPAN: Honshu: ♂, “ 岐阜県ţDzmae尾水鳥 | [JAPAN; Honshu] | Neomidori (alt. 500 m) | Motosu-shi | Gifu, 10–V–2020 | Kôhei Kawamura leg. | 35°36’31”N, 136°35’08”E ” [printed on white label], “HOLOTYPE | Lathrobium minoccidentale | sp. nov. | Des. Y. Senda, 2023” [printed on red label with black border]. (EUMJ). Paratypes: 1♂, 3♀♀, same data as holotype (EUMJ, pcYS); 1 ♂, Midori-dani, Gifu Pref., 5.VI.1983, M. Satô leg. (EUMJ).
Diagnosis. The new species is similar to Lathrobium bigladiosum Assing, 2019, but distinguishable from it by the following characteristics: 1) posterior excision of male abdominal sternite VIII comparatively shallow; 2) aedeagal ventral process very slender in lateral view; 3) apical part of aedeagal dorsal plate lanceolate (while in L. bigladiosum: posterior excision of male abdominal sternite VIII comparatively deep; aedeagal ventral process slightly slender in lateral view; apical part of aedeagal dorsal plate semilanceolate).
Description. Colouration: Body dark reddish brown to 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 usually dark reddish brown in sutural and apical area.
Male. Body elongate, subparallel-sided, slightly flattened dorsally, shining. Head subtrapezoid in dorsal view, lateral sides gently 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 ≈ 0.6; antennomere I widest at about apical 1/3, dilated to widest point, thence gently contracted toward apex; antennomere 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: 2.5, 1.8, 2.0, 1.7, 1.7, 1.7, 1.7, 1.6, 1.6, 1.6, 2.2; relative lengths of antennomeres from base to apex: 23.1: 10.0: 12.5: 10.0: 10.0: 10.0: 10.0: 10.0: 10.0: 10.0: 13.1, and relative widths: 16.7: 10.0: 11.1: 10.4: 10.4: 10.4: 10.4: 11.1: 11.1: 11.1: 10.7.
Pronotum oblong, widest at anterior 1/3, PL/PW ≈ 1.2, PL/HL ≈ 1.3, PW/HW ≈ 1.0, lateral sides gently arcuate; disc sparsely covered with coarse and setiferous punctures except median smooth area; anterior margin feebly emarginate at middle, broadly rounded at corners; posterior margin feebly arcuate, rounded at corners. Scutellar shield impunctate, 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 ≈ 0.8, EL/PL ≈ 0.7, EW/PW ≈ 1.1; disc covered with shallow punctures, sparsely covered with fine brownish pubescence. Hind wings absent. Legs simple, rather slender, covered with golden pubescence; protarsomeres I–IV strongly dilated.
Abdomen covered with minute punctures, densely covered with dark brownish pubescence; sternite VI (Fig. 6A) without median depression, but sparsely covered with short black setae posteromedial area; sternite VII (Fig. 6A) with very weak median depression, which is sparsely covered with short black setae, feebly emarginate at posterior margin; tergum VIII gently arcuate at posterior margin; sternite VIII (Fig. 6A) with median depression, which is sparsely covered with short black setae, with comparatively shallow triangular posterior excision, lateral side of posterior excision not produced on posterior margin; tergum IX setigerous except on basal 1/4, with posterolateral projections as long as 1/5 of tergum IX and curved dorsally from the apical 1/3 to pointed apex; sternite IX elongate, widest at basal 1/4, narrowed apically, setigerous in 2/3, with posterior margin arcuate; tergum X subtrapezoidal, widest at basal corners, with few setae and pores, with posterior margin arcuate.
Aedeagus (Fig. 6B–D) very elongate, 2.30 mm long, sclerotised except membranous dorsal side; dorsal plate elongate, asymmetric, very slender in basal 1/3, but abruptly dilated at basal 1/3, slightly twisted apically, lateral sides emarginated before apex, with lanceolate apex in lateral view; ventral process asymmetric, widest at base, gently contracted toward acute apex, curved ventrally, slightly sinuate in apical 1/ 3 in ventral view. Endophallus poorly developed, without sclerites.
Female. Similar to male in general appearance. Length/width ratio of each antennomere I to XI as follows: 3.1, 1.6, 1.9, 1.6, 1.6, 1.6, 1.6, 1.4, 1.4, 1.4, 2.0; relative lengths of antennomeres from base to apex: 24.3: 10.7: 13.0: 10.0: 10.3: 10.3: 10.7: 10.7: 10.7: 10.7: 13.7, and relative widths: 16.7: 10.0: 11.1: 10.4: 10.4: 10.4: 10.4: 11.1: 11.1: 11.1: 10.7. HL/HW ≈ 0.9; AL/FBL ≈ 0.6; PL/PW ≈ 1.2; PL/HL ≈ 1.3; PW/HW ≈ 1.0; EL/EW ≈ 0.9; EL/PL ≈ 0.7; EW/PW ≈ 1.0.
Tergum VIII (Fig. 6E) feebly project at middle of posterior margin; sternite VIII (Fig. 6F) produced at middle of posterior margin, which is arcuate and fringed with micropubescence; tergum IX (Fig. 6E–F) similar to male, but with thicker posterolateral projections, with large subtriangular flap-like ventral plate on base; tergum X (Fig. 6E) similar to male. Gonocoxites (Fig. 6F): lateral gonocoxal plate (distal and proximal gonocoxites fused) elongate, setigerous, with few setae in apical area, with rounded apex.
Measurements. Male (n = 2)—BL: 7.91 & 7.56 mm; FBL: 3.62 & 3.36 mm; HL: 1.11 & 1.05 mm; HW: 1.20 & 1.14 mm; AL: 2.27 mm & 2.19 mm; PL: 1.44 & 1.36 mm; PW: 1.21 & 1.12 mm; EL: 1.07 & 0.95 mm; EW: 1.28 & 1.22 mm.
Female (n = 3)—BL: 7.67–7.98 mm (7.79± 0.16 mm); FBL: 3.49–3.69 mm (3.56± 0.11 mm); HL: 1.05–1.11 mm (1.09± 0.04 mm); HW: 1.17–1.21 mm (1.18± 0.03 mm); AL: 2.16–2.29 mm (2.22± 0.07 mm); PL: 1.39–1.47 mm (1.42± 0.05 mm); PW: 1.12–1.23 mm (1.16± 0.06 mm); EL: 1.01–1.10 mm (1.06± 0.04 mm); EW: 1.19–1.23 mm (1.21± 0.02 mm).
Distribution. Japan: Central Honshu (southwestern area of Gifu Prefecture) (Fig. 8).
Etymology. The specific name is a combination of the “Mino” (which means a traditional name of southern area of Gifu Prefecture) and the genitive of the Latin adjective “occidentalis” (which means western). Thus, it alludes to the distribution area of this species.
Comments. This new species is tentatively placed in the Lathrobium brachypterum group (sensu Senda, 2023b), but this treatment requires further consideration. Possibly, this species and related congeners with very elongate aedeagus are appropriately classified in a separate group. According to the collector of the type specimens, K. Kawamura (per. comm.), they were collected from subterranean zone.
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 512-514, DOI: 10.11646/zootaxa.5403.5.1, http://zenodo.org/record/10562427