Moctherus obscurabasis, Hunting, Wesley & Yang, Man-Miao, 2019

Hunting, Wesley & Yang, Man-Miao, 2019, A taxonomic review of the pericaline ground-beetles in Taiwan, with descriptions of new species (Coleoptera, Carabidae, Lebiini), ZooKeys 816, pp. 1-164 : 131-133

Moctherus obscurabasis sp. n. Figs 97A, B, 98, 99 A–D, 102B, 103

Etymology.

From Latin obscura and basis, in reference to the dull appearance of the baso-medial half of the elytra due to the dense setae and relatively wide and shallow punctures.

Types and other material examined.

Holotype (male) labeled “Holotype” [circular, ringed with red]; "TAIWAN: Nantou Co./Huisun Forest Station/Area, May 23, 2012/24.0874N, 121.0301E"; "veg. on trail to waterfall/~750m, Acc. Ti-168a/Coll. W. M. Hunting"; " NCHU# 100522". Two paratypes of M. obscurabasis : one male and one female. For further details see EH Strickland Virtual Entomology Museum Database.

Diagnosis.

Specimens of this species are easily distinguished from other species of Mochtherus by the large size (more than 7.5 mm) and the baso-medial half of the elytra with setae long and dense, punctures wide, shallow and somewhat regularly spaced, giving a distinctive dull texture.

Description.

OBL 8.17 - 8.67 mm. Length (n = one male, two females): head 0.84, pronotum 1.32 - 1.40, elytra 4.75 - 5.17, metepisternum 1.20 - 1.40 mm; width: head 1.76 - 1.84, pronotum 2.00 - 2.16, elytra 3.33 - 3.50, metepisternum 0.56 - 0.76 mm.

Body proportions. HW/HL 2.14 - 2.19; PWM/PL 1.52 - 1.55; EL/EW 1.43 - 1.55; ML/MW 1.94 - 2.19 mm.

Color. Fig. 97A, B. Dorsum of head rufo-brunneous to piceous, clypeus rufo-brunneous to brunneo-piceous, lighter than head, labrum brunneous, brunneo-piceous to piceous centrally; palpi and antennae brunneo-testaceous to brunneous; pronotum brunneous to brunneo-piceous, margins somewhat lighter; elytral disc brunneo-piceous to piceous, suture and margins slightly lighter, disc with four testaceous to rufo-testaceous maculaee, two anterior and two posterior, anterior macula ovoid, from stria 3 or 4 to interval 8, nearest to base at interval 7, closest to apex in interval 5 or 6, posterior macula circular to ovoid, from suture to interval 4 or 5), closest to base in interval 3 or 4, nearest to apex in interval 3 or 4; ventral surface brunneo-testaceous to brunneous, metepisternum brunneous to brunneo-piceous, darker; legs brunneous, light.

Microsculpture. Dorsum of head with mesh pattern somewhat granulate, isodiametric, labrum with sculpticells shallow, almost isodiametric; pronotum with microsculpture transverse; elytra with sculpticells transverse, most easily observed in apical half; metepisternum with microsculpture somewhat granulate, almost isodiametric to transverse; other ventral surfaces with microsculpture transverse.

Macrosculpture and pilosity. Dorsum of head faintly and longitudinally rugulose, with scattered setigerous punctures, setae short and fine between eyes, somewhat long er behind eye, clypeus relatively smooth, with several scattered setigerous punctures, labrum smooth, with several short setae in apical half; scrobe of mandible with few setae near base; pronotum faintly rugulose transversely, punctate and densely setose; elytra with intervals punctate and setose, baso-medial half with setae longer and more dense, punctures wide, shallow, dense and somewhat regularly spaced, giving distinctive texture, striae faintly punctate, setae hardly visible at 50 ×; ventral surface with randomly scattered setigerous punctures, setae relatively dense and easily visible in lateral view.

Fixed setae. Elytra with two setae in interval 2, one seta just back from mid-length, one seta in apical 1/6.

Luster. Dorsal surface moderately dull with basal third of elytra dull; ventral thoracic sterna and abdominal sterna moderately glossy.

Head. Mandibles with wide base, short; labrum longer than wide, rectangular; mentum with shallow tooth; eyes convex.

Pronotum. Fig. 98. Anterior transverse impression very shallow; posterior transverse impression moderately deep; median longitudinal impression moderately deep; disc convex, apical margin emarginate, basal angles obtuse; lateral margins broadly rounded in apical portion, markedly sinuate from lateral seta to base.

Elytra. Lateral margin smooth, slightly rounded along length.

Legs. Tarsal claws pectinate, 4-5 denticles per claw, apical denticles rather long.

Male genitalia. Fig. 99 A–D. Length 1.2 mm. Phallus relatively narrow, uniform width along length, apex somewhat elongate and narrow, curved along length to follow contour of phallus; endophallus with width relatively uniform along length, right angled lobe at base, one basal microtrichial field (mtf).

Female genitalia. Fig. 102B. Width 0.96 mm. Two lateral ensiform setae (les), basal seta longer than apical seta. One spermatheca (sp1), cylindrical and elongate tapering towards apex, with markedly elongate apical end; ring sclerite (srs) separating spermatheca duct from spermatheca; one spermathecal accessory gland (sg), spermathecal gland duct (sgd) attachment site on right side of ring sclerite when viewed from ventral aspect.

Habitat, habits, and seasonal occurrence.

The known elevational range of M. obscurabasis is from 750 to 1300 meters. Little is known about the habits of this species however, the single specimen collected was found in secondary, mixed forest, on the trunk of a live tree. The tree was on a dirt path and the time was approximately 9:00 pm. Specimens have been collected in May and July and the only known method of collecting is by hand.

Geographical distribution.

Mochtherus obscurabasis is known only from Taiwan. See Figure 103.