Chandleriella yunnanica, Yin, 2019

Yin, Zi-Wei, 2019, First record of the genus Chandleriella Hlaváč (Coleoptera: Staphylinidae: Pselaphinae) from China, with description of a second species, Zootaxa 4571 (3), pp. 432-438 : 434-435

Chandleriella yunnanica sp. nov.

( Figs 1–4 )

Type material (6 exs). Holotype: CHINA: ♂, ‘ China: Yunnan, Lincang City (临沧市), Yun Co. (云县), Manwan Town (漫湾镇), Shuibatou Vill. (水坝头村), 23°52′14.67″N, 100°11′45.92″E, 2200 m, 25.viii.2018, Zi-Chun Xiong leg. / HOLOTYPE (red) ♂, Chandleriella yunnanica sp. n., det. Z.-W. Yin , 2019, SNUC’ ( SNUC) . Paratypes: CHINA: 3 ♀♀, same label data as the holotype ( SNUC) ; 2 ♂♂, ‘ China: Yunnan, Yuxi City (玉溪市), Xinping Co. (新平县), Shuitang Town (水塘镇), mid. pt. Ailao Mts. (哀牢山脉中段), alt. 2000 m, 28.viii.2009, Xiao-Yu Zhu Leg.’ ( SNUC) . Each paratype bears a following type label: ‘ PARATYPE (yellow) ♂ (or ♀), Chandleriella yunnanica sp. n., det. Z.-W. Yin , 2019, SNUC’ .

Diagnosis. Body large-sized, length over 3.50 mm; antennal club formed by antennomere 11 alone; male antennomere 11 strongly enlarged and modified, bowl-like; metaventrite greatly raised to form median rostrum; aedeagus symmetric, median lobe tri-lobed at apex; parameres elongate, narrowing from base toward apex, with several long apical setae; female has simply enlarged, unmodified antennomere 11, and simple metaventrite.

Description. Male ( Fig. 1A ). Body length (combined length of head, pronotum, elytra, and pronotum) 3.50– 3.90 mm. Integument of dorsal surface with fine punctation and dense pubescence. Head elongate, sub-hexagonal, length from clypeal anterior margin to head base 0.66–0.76 mm, maximum width (across eyes) 0.60–0.65 mm; frontal rostrum moderately broad, setose C-shaped sulci surrounding antennal insertions clearly visible in dorsal view; each eye composed of about 70 facets. Postocular margins long, oblique medially, angulate at posterolateral corners. Antennae moderately elongate, length 2.07–2.18 mm; antennal club formed by single terminal antennomere; scape elongate, slightly shorter than antennomeres 2–3 combined, antennomeres 2–10 submoniliform, with 8–10 distinctly transverse and successively broader, antennomere 11 ( Fig. 2A ) strongly enlarged, hemispherical, with upper surface markedly concaved, bowl-like. Maxillary palpus simple, palpomeres 1 minute, palpomeres 2 (0.34 mm) elongate, slightly pedunculate at basal half, palpomeres 3 (0.16 mm) widest at apex, palpomeres 4 lengthily fusiform. Pronotum slightly wider than long, length along midline 0.75–0.78 mm, maximum width 0.66–0.76 mm, widest near anterior two-fifths, constricted from widest point toward apex and base; disc moderately convex. Elytra sub-trapezoidal, wider than long, length along suture 1.0– 1.05 mm, maximum width 1.37–1.44 mm, widest at posterior third; discal stria shallow and wide, extending to half of elytral length. Metaventrite ( Fig. 2C ) finely punctate, strongly elevated to form rostrum at middle, anterior margin of rostrum well-demarcated from other part of metaventrite, posterior half of rostrum broadly impressed and inclined posteriorly. All legs elongate and slender; femora broadest near middle; tibiae nearly straight and slightly broadened apically. Abdomen broadest at tergite IV (first visible tergite), length of dorsally visible part along midline 1.02–1.25 mm, maximum width 1.37–1.44 mm; tergite IV longest, more than twice as long as tergite V, with broad impression at base; discal carinae short, but thick and conspicuous. Aedeagus ( Fig. 3 ) moderately sclerotized, symmetric in dorso-ventral view, length 0.53–0.58 mm; median lobe strongly curved in lateral view, broad at base, ventrally broadening from base toward apex, split into three lobes at apex; endophallus comprised of elongate, membranous structures; parameres extremely elongate, symmetric, each bearing several long apical setae.

Female ( Fig. 1B ). General external morphology similar to male; antennomere 11 enlarged and unmodified; metaventrite simple, lacking rostrum; each eye composed of about 60 facets. Measurements (as for male): body length 3.83–3.85 mm, length/width of head 0.77–0.78 mm / 0.63 mm, length/width of pronotum 0.74 mm / 0.72 mm, length/width of elytra 1.05 mm / 1.13–1.18 mm, length/width of abdomen 1.25–1.26 mm / 1.41 mm.

Intraspecific variation. The populations of Shuibatou Village and Ailao Mountain, separated by two mountain ranges and Lancang River ( Fig. 4B ), show differences in body size (3.50–3.59 mm vs. 3.90 mm), and form of the median lobe of the aedeagus ( Fig. 3 ). However, the proportions of the body parts and antennomeres, and especially the male external sexual features, e.g., the forms of antennomere 11 ( Fig. 2A ), and projection of the metaventrite ( Fig. 2C ), are rather stable. The differences in body size and the aedeagus are thus considered to be intraspecific variations of the same species.

Comparison. The male of Chandleriella yunnanica can be readily separated from its only congener, C. termitophila (Bryant) from Sarawak, by the much larger body size (3.5–3.9 mm vs. 3.0 mm), the strongly modified, bowl-like antennomere 11 of the male, and the different configurations of the aedeagus. Chandleriella termitophila possesses a simply enlarged antennomere 11 that lacks modification ( Hlaváč 2000: figs 1, 3); and when viewed laterally, the median lobe of the new species is evenly narrowing from base toward apex, while it is greatly expanded at the basal two-fifths of C. termitophila ( Hlaváč 2000: fig. 4).

Biology and distribution. The circumstances from which the two individuals of the Ailao Mountains were collected were not specified; however, all those from Shuibatou Village were taken from a colony of an Ectomomyrmex ant nesting in a fallen decomposing log (Z.-C. Xiong pers. comm.), indicating probable myrmecophily of this species; collected with them was an Awas sinicus Yin & Li , which represents the first host record for this rarely encountered species, and agrees with a previously published scenario ( Yin 2017) regarding the host association of Awas . The new species is currently known from two localities in Yunnan, southwestern China ( Fig. 4 ).

Etymology. The new specific epithet refers to the province where the type locality is located, i.e., Yunnan.

Figures

FIGURE 1. Dorsal habitus of Chandleriella yunnanica. A. Male. B. Female. Scale bar: 1.5 mm.

FIGURE 2. Morphological details of Chandleriella yunnanica. A. Male antennomere IX–XI. B. Female antennomere IX–XI. C. Median rostrum of male metaventrite. Scale bar: 0.2 mm in A, B; 0.5 mm in C.

FIGURE 3. Aedeagus of Chandleriella yunnanica, in lateral (A, D), ventral (B, E), and dorso-axial (C, F) view. A–C. Population of the Ailao Mountains. D–F. Population of Manwan Town. Scale bar: 0.2 mm.

FIGURE 4. Distribution of Chandleriella species (A) (Square: C. yunnanica. Circle: C. termitophila), and detailed distribution of C. yunnanica in Yunnan, Southwest China (B).