Stenothemus acuticollis Y. Yang & X. Yang, 2021

Ge, Shujuan, Yang, Xingke, Liu, Haoyu & Yang, Yuxia, 2021, Studies on the Stenothemus harmandi species-group (Coleoptera, Cantharidae), with descriptions of two new species from China, Biodiversity Data Journal 9, pp. 68659-68659 : 68659

Stenothemus acuticollis Y. Yang & X. Yang sp. n.

Materials

Type status: Holotype. Occurrence: recordedBy: Lin Meiying; individualCount: 1; sex: male; lifeStage: adult; Taxon : scientificName: Stenothemus acuticollis; Location : country: China; stateProvince: Yunnan; locality: Tengchong , Wuhexiang , Zhengding ; verbatimElevation: 1873 m; verbatimCoordinateSystem: 24°51′ N, 98°44′ E; Record Level: collectionCode: Insects; ownerInstitutionCode: IZAS; basisOfRecord: Preserved Specimen Type status: Paratype. Occurrence: recordedBy: Lin Meiying; individualCount: 8; sex: females; lifeStage: adult; Taxon : scientificName: Stenothemus acuticollis; Location : country: China; stateProvince: Yunnan; locality: Tengchong , Wuhexiang , Zhengding ; verbatimElevation: 1873 m; verbatimCoordinates: 24°51′ N, 98°44′ E; Record Level: collectionCode: Insects; ownerInstitutionCode: IZAS; basisOfRecord: Preserved Specimen Type status: Paratype. Occurrence: recordedBy: Dong Yanju; individualCount: 1; sex: male; lifeStage: adult; Taxon : scientificName: Stenothemus acuticollis; Location : country: China; stateProvince: Yunnan; locality: Mangkuan , Baihualing ; Event : eventDate: 02.03.2013; Record Level : collectionCode: Insects ; ownerInstitutionCode: MHBU; basisOfRecord: Preserved Specimen Type status: Paratype. Occurrence: recordedBy: Sun Kai & Li Zhipeng; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Stenothemus acuticollis; Location : country: China ; stateProvince: Yunnan; locality: Gongshan , Dulongjiang ; Event : eventDate: 14.08.2018; Record Level : collectionCode: Insects ; ownerInstitutionCode: MHBU; basisOfRecord: Preserved Specimen Type status: Paratype. Occurrence: recordedBy: Xu Jishan & Zhang Jianxiong; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Stenothemus acuticollis; Location : country: China ; stateProvince: Yunnan; locality: Zhenyuan , Jiujia ; Record Level : collectionCode: Insects ; ownerInstitutionCode: MHBU; basisOfRecord: Preserved Specimen

Description

Body length (both sexes): 6.4-8.1 mm (6.5 mm in holotype); width: 1.5-2.3 mm (1.5 mm in holotype).

Male (Fig. 1 c).

Body pale yellow mixed with irregular dark brown markings, except head black, with a reddish-brown marking on midline of vertex, apex of each antennomere yellow. Body densely covered with pale yellow pubescence, mixed with semi-recumbent pale yellow pubescence.

Head. Surface densely punctate, each side with a smooth, rectangular impression behind antennal fossa; eyes strongly protruding, head across eyes nearly as wide as pronotum; terminal maxillary palpomeres elongate-triangular, widest at mid-length; antennae filiform, extending to three-quarter length of elytra, antennomeres II 2.8 times as long as wide at apices, III 1.1 times longer than II, V longest, VI to X gradually shortened, XI longer than X, pointed at apex.

Pronotum. 1.1 times wider than long, anterior margin arcuate, anterior angles rounded, lateral margins arcuate, posterior margin bisinuate and narrowly bordered, posterior angles sharp, protruding, disc strongly convex on postero-lateral parts, surface densely punctate.

Elytra. 3.0 times as long as combined humeral width, 4.2 times longer than pronotum, lateral margins diverging posteriorly, surface densely punctuate, longitudinal costae hardly visible.

Aedeagus (Fig. 2 ). Strongly swollen dorsally at base in lateral view, strongly reduced in diameter apically; basal piece (bp, phallobase) nearly as long as dorsal plate (dp) of each paramere, with a large, bifurcate conjoined middle nodule (nd) at base of ventral side; ventral processes (vp) of parameres approaching each other in ventral view, long and thickened apically, bent ventrally at an angle of about 60 degrees to median lobe in lateral view; dorsal plates shorter than ventral processes, greatly narrowed apically (apical part about one-third as wide as basal part); laterophyses (la) rounded at apices, exceeding into emargination between dorsal plates.

Female.

Body stouter than in male, eyes smaller, head across eyes about 0.9 times width of pronotum, antennae shorter and approximately extending to elytral mid-length; elytra with lateral margins diverging posteriorly more strongly in dorsal view.

Internal organ of reproductive system (Fig. 4 a). Vagina (va) elongate, with median oviduct (ov) situated at ventro-apical part, vagina abruptly narrowed in apical part and extended into a short tube from where diverticulum and spermathecal duct are arising; diverticulum (di) short, 0.1 times as long as adult body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct (sd) 0.1 times as long as diverticulum; spermatheca (sp) slender tube-shaped and spiral, thinner than spermathecal duct and 1.1 times as long as diverticulum, with basal part extended into a short tube, at opening of accessory gland (ag). Accessory gland thin in basal part and the remainder relatively thick, 1.6 times longer than spermatheca.

Abdominal sternite VIII (Fig. 6 a, b). Obliquely narrowed posteriorly, latero-apical angles rounded, posterior margin shallowly and roundly emarginate in the middle and arcuate on both sides, present behind the notch with a membrane which is sclerotised.

Diagnosis

Most similar to S. harmandi (Bourgeois, 1902) in the shapes of pronotum and ventral process of each paramere of the aedeagus, but differs in the aedeagus which is strongly swollen dorsally at base in lateral view, with the dorsal plate of each paramere being abruptly narrowed apically in dorsal view. Unlike in the latter, the aedeagus is moderately swollen at the basal part and the dorsal plate of each paramere is evenly narrowed apically ( Yang et al. 2014: figs. 21-23). For the female, abdominal sternite VIII is shallowly emarginate in the middle of posterior margin, while deeply emarginate in S. harmandi ( Yang et al. 2014: fig.11).

It also resembles S. fugongensis Y. Yang et X. Yang, 2014 in the body size and colouration and the shape of ventral process of each paramere of the aedeagus, but can be easily distinguished from S. fugongensis by the pronotum with sharp posterior angles and the aedeagus has the dorsal plate of each paramere abruptly narrowed apically in dorsal view with the laterophyses being rounded at the apices in lateral view. In comparison, S. fugongensis has the pronotum with rounded posterior angles ( Yang et al. 2014: fig. 3) and the aedeagus has the dorsal plate of each paramere evenly narrowed apically, with the laterophyses hooked at the apices in lateral view ( Yang et al. 2014: figs. 24-26).

Etymology

The specific name is derived from the Latin acutus (sharp) and collum (neck), referring to its pronutum with sharp posterior angles.

Distribution

China (Yunnan).

Figures

Figure 2. Aedeagus of S. acuticollis sp. n.: A. ventral view; B. dorsal view; C. lateral view; bp: basal piece; dp: dorsal plates; la: laterophyse; nd: nodule; vp: ventral processes of parameres; ag: accessory gland; Scale bar: 1.0 mm