Helophorus (Lihelophorus), Zaitzev, 1908

Angus, Robert B., Jia, Fenglong, Chen, Zhen-ning, Zhang, Ying, Vondráček, Dominik, Fikáček, Martin & Sw, London, 2016, Taxonomy, larval morphology and cytogenetics of Lihelophorus, the Tibetan endemic subgenus of Helophorus (Coleoptera: Hydrophiloidea), Acta Entomologica Musei Nationalis Pragae 56 (1), pp. 109-148 : 114

Subgenus Lihelophorus Zaitzev, 1908

Type species. Helophorus (L.) lamicola Zaitzev, 1908 (designated by HANSEN 1991: 285).

Diagnosis of adults. Body moderately large to large (4.4–6.1 mm); antenna with 9 antennomeres; maxillary palpus 4 asymmetrical ( Figs 4–5 ); labial palpus ca. as long as cardo ( Fig. 1a–b ); labial palpomere 3 slightly asymmetrical, with fringe of long setae ( Figs 1b, g ); gular sutures widely separate ( Fig. 1a ); clypeus and frons without well-defined granules ( Figs 4–5 ); pronotum with 5 longitudinal grooves (largely reduced and weakly distinct only posteriorly in H. lamicola ), without granules ( Figs 2a,c,e , 4–5 ); scutellary stria of elytron present ( Figs 2b,d,f ); elytron without elevated alternate intervals, tubercles or erect setae ( Fig. 3 ); elytral interval 10 flat, i.e. elytral flanks absent ( Figs 2j–k ); epipleuron with wide inner pubescent portion ( Fig. 2j ); whole metaventrite and abdominal ventrites with dense pubescence; meso- and metatarsomere 2 longer than metatarsomere 3 ( Figs 1h–j ); tibiae and tarsi of middle and posterior legs with row of long swimming-hairs ( Figs 1h–k ); posterior margin of last abdominal ventrite with minute irregular teeth ( Fig. 2i ).

By body size and general habitus, the presence of distinct scutellary stria and asymmetrical ultimate maxillary palpomere, the Lihelophorus species resemble representatives of subgenera Helophorus s. str. and Gephelophorus Sharp, 1915 . They differ from them by (1) presence of series of swimming-hairs on meso- and metatibiae and (2) flat last elytral interval. The well-developed series of swimming-hairs on meso- and metatibiae are only present in the species of the subgenus Rhopalohelophorus Kuwert, 1886 , which can be however easily distinguished from Lihelophorus by the absence of scutellary stria on the elytron.

Distribution. Endemic to the Tibetan Plateau (Fig. 7a)

Analysis of molecular data. The division of the molecular dataset into three partitions was selected as the best partition scheme, with different substitution model selected for each codon position: GTR+G for the first, F81+I for the second and HKY+G for the third codon position. The analysis revealed strongly supported clades for the subgenus Lihelophorus as well as for its three species recognized by means of morphology ( Fig. 9a ). Both larval morphotypes reared from egg cases laid by field-collected adults were reliably assigned to adults from the same locality: the larva with abdominal appendages (MF660) to H. lamicola and the larva without the appendages (MF666) to H. yangae sp. nov. Intraspecific variation of cox1 sequences ranged between 0.0–2.9 % (mean 1.9 %) in H. lamicola , 0.8–6.3 % (mean 4.4 %) in H. ser and 0.0–0.1 % (mean 0.1 %) in H. yangae sp. nov. Interspecific distances range from 10.4–13.4 %.

Figures

Fig.4. Details of the head and pronotum of the Helophorus (Lihelophorus) specimens.a–c – H. lamicola Zaitzev,1908 (a – Qinghai: Zhaling Hu (lectotype); b–c – Qinghai: Golo). d–h – H. ser Zaitzev, 1908 (d – Qinghai: valley of Alag Hu lake (lectotype); e–f – Qinghai: Golo; g – Xizang, Nyainqentanglha Feng; h – Gansu: Xiahe env.). Not to scale.

Fig. 5. Details of the head and pronotum of the Helophorus (Lihelophorus) yangae sp. nov. (a – Xizang: 90 km W of Amdo; b,d – Qinghai: Golo; c – Xizang: 25 km W of Amdo; e – India: Kar Tso (Orchymont coll.). Not to scale.

Fig. 1. Adult morphology of Helophorus (Lihelophorus). a–b – H. yangae sp. nov. (a – ventral view of the head; b – detail of mentum and labial palps); c–d – maxillary galea and lacinia (c – H. yangae sp. nov.; d – H. ser Zaitzev, 1908); e–f – mandible (e – H. yangae sp. nov.; f – H. ser); g – labial palpus of H. ser; h–l – hind legs in dorsal view (h – H. yangae sp. nov.; i – H. ser; j – H. lamicola Zaitzev, 1908; k – detail of apex of tibia and base of tarsus of H. lamicola; l – detail of tarsomere 5 and claw of H. ser). Abbreviations: sh – swimming hairs. Not to scale.

Fig. 2. Adult morphology of Helophorus (Lihelophorus). a–f – details of left half of pronotum (a,c,e) and base of left elytron (b, d, f): a–b – H. yangae sp. nov.; c–d – H. ser Zaitzev, 1908; e–f – H. lamicola Zaitzev, 1908; arrow in (a) shows remnants of pronotal granulations, arrows in (b, d, f) show scutellary stria. g–h – prothoracic hypomeron and ‘suprapleural area’ (g – H. yangae sp. nov.; h – H. ser). i – detail of posterior margin of abdominal ventrite 5 of H. ser, showing the irregular denticulation. j – ventral view of the thorax of H. ser. k – dorsolateral portion of left elytron of H. lamicola. Abbreviations: ep – epipleuron; li – last elytral interval. Not to scale.

Fig. 3. Habitus of the species of Helophorus (Lihelophorus). a–c – H. lamicola Zaitzev, 1908 (a – Qinghai: Zhaling Hu (lectotype); b–c – Quinghai: Golo).d–g – H.ser Zaitzev, 1908 (d–e – Qinghai:Golo; f – Xizang, Nyainqentanglha Feng; g – Gansu: Xiahe env.). h–k – H. yangae sp. nov. (h – Xizang: 90 km W of Amdo; i – Xizang: 25 km W of Amdo; j – Qinghai: Golo; k – India: Kar Tso (Orchymont coll.)). All specimens to scale.

Fig.9.Association of reared larvae andfield-collected adults of Helophorus (Lihelophorus) based on cox1 sequences. a – Bayesian inference of newly obtained and available GenBank sequences; b–c – habitus of reared larvae (b – H. yangae sp. nov.; c – H. lamicola Zaitzev, 1908).