Helophorus (Lihelophorus) yangae, Angus & Jia & Chen & Zhang & Vondráček & Fikáček & Sw, 2016

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 : 127-137

Helophorus (Lihelophorus) yangae sp. nov.

( Figs 8c–d, f, i–j ; 9b ; 10 ; 12c–d ; 13b, f, g–h ; 14e–f )

Larval material examined (5 larvae). 1 first instar larva ( NMPC, DNA voucher MF666 ): CHINA: QINGHAI: Golo, Maduo, roadside pools near Yematan , 34°40′47″″N 99°03′57″″E, 4240 m a.s.l., 8.vi.2013, R. B. Angus, F. L. Jia & Y. Zhang lgt .; 4 first instar larvae (BMNH): same label data. All larvae were reared from the single egg case (deposited in BMNH) laid by the field-collected female, association with adults from the same locality was confirmed by the cox1 sequence data .

Egg case ( Fig. 8f ). Consisting of an egg-bag surmounted by a thin trailing mast which takes the form of a long narrow tube, thus corresponding to Type 4 egg case of ANGUS (1992) ; it is similar to that of H. lamicola , but with a shorter mast which may represent individual variation. Larva. General morphology. Body ( Fig. 9b ) elongate, slender, almost parallel-sided. Body length (without urogomphi) ca. 3.0 mm. Head ( Figs 8c–d ) subquadrate in shape, ca. 1.15× wider than long, prognathous, with occipital foramen directing posteriorly.

Head width 0.43–0.47 mm (n = 5). Parietale with numerous cuticular spines dorsally, laterally and ventrally. Frontal lines V-shaped, arising posteriorly of antennal socket and reaching posterior margin of head capsule, nearly straight; coronal line absent. Antennal sockets situated on the laterodorsal portion of head. Frontoclypeus ( Fig. 12c ) with small asymmetrical

◄Fig. 7. Distribution and habitats of Lihelophorus species. a – known distribution of Lihelophorus species based on examined specimens. Examples of habitats (see the letters in Fig. 7a for geographic position of each locality): b – Qinghai: Golo, Maduo, roadside pools on river flats, 4290 m (habitat of H. ser and H. yangae sp. nov.); c – Qinghai: Golo, Huamuxia, Zuimatan, roadside pool, 4141 m (habitat of H. lamicola , H. ser and H. yangae sp. nov.); d – Xizang: Gongbujiangda, 4155 m (habitat of H. yangae sp. nov.); e – Xizang: E Nyainqentanglha Feng, eastern slope of Lha Tsu valley, 5000–5350 m (habitat of H. ser ); f – Gansu: Xiahe env., 2940 m (habitat of H. ser ); g – Xizang: Dangxiong, Yangbajing town, 4320 m (habitat of H. yangae sp. nov.).

nasale bearing single median tooth, and large symmetrical epistomal lobes overlapping nasale, well-sclerotized including laterally. Six small stemmata situated on anterolateral portion of parietale, widely separated from each other. Gular suture absent, posterior tentorial pits distinct, situated anteromesally. Cervical sclerites absent. Antenna ( Fig. 13f ) 3-segmented, long and rather stout. Scape ca. as long as pedicel, pedicel slightly widened distally, flagellum slightly shorter than scape.

Mandibles ( Fig. 13b ) symmetrical, with falcate apical portion. Retinaculum with two teeth; distal tooth large, bearing dense tuft of cuticular spines; basal tooth small, lacking cuticular projections. Basal inner face not projecting, with a basal field of fine spine-like cuticular projections.

Maxilla ( Figs 14e–f ) 6-segmented (including cardo), slightly longer than antenna. Cardo rather small, situated laterally, and associated with two additional sclerites lying between cardo and labium. Stipes ca. as long as palpifer, subcylindrical; palpifer completely sclerotized, mesally with a long well-sclerotized finger-like galea which has an additional ring-like sclerite basally. Maxillary palpus with 3 segments, ca. as long as palpifer; palpomere 1 ca. half as long palpomere 2 and 3 each.

Labium ( Figs 13g –h ). Submentum large, trapezoid, fused with parietale, submental suture indistinct. Mentum short, ca. as long as wide, with cuticular spines on dorsal surface. Prementum V-shaped, ligula absent. Labial palpus 2-segmented, with basal palpomere ca. 2× shorter than distal palpomere.

Thorax. Prothorax ca. as wide as head capsule. Proscutum, meso- and metanotum ( Fig. 15f ) each formed by a large plate subdivided mesally by a sagittal line. Ventral portion of prothorax ( Fig. 8d ) with a pair of small widely isolated presternal sclerites, each articulating posterolaterally with a precoxal sclerite which connects presternum with coxal articulation; remaining parts largely membranous. Mesothorax with two pleural sclerites: the anterior one bulge-like bearing spiracle, the posterior rounded and flat. Legs long, clearly visible in dorsal view, all pairs similar in shape. Leg 5-segmented ( Figs 15b–c ); all pairs of coxae well separated from each other, procoxae slightly closer to each other than meso- and metacoxae; trochanter ca. half as long as femur, rather firmly joined with femur; tibiotarsus cylindrical, ca. as long as trochanter and femur combined. Claw ca. as long as tibiotarsus, slightly bent ventrad.

Abdomen ( Figs 9b , 15e–f, g ) with 9 well developed segments, not subdivided into folds. Segments 1–8 each with a pair of large central (ʻdorsal scleritesʼ sensu ANGUS 1992) and smaller lateral sclerites (ʻdorsolateral scleritesʼ sensu ANGUS 1992); dorsally, one small sclerite below spiracle (ʻlateral scleriteʼ sensu ANGUS 1992), and transverse series of three small sclerites ventrally; spiracle is situated in membranose area. Segment 9 with large entire sclerite dorsally; bearing a pair of long three-segmented urogomphi ( Fig. 15j ). Spiracular atrium not developed.

Primary chaetotaxy. Head. Frontale with 44 sensilla ( Figs 10b , 12c ). Central part with three pairs of sensilla diverging posteriad, small seta FR1 situated at midlength near frontal line, pore FR2 and small seta FR3 close to each other and situated more anteromesally. Lateral portions posterior to antennal socket each with two setae and one pore: short seta FR5 situated close to frontal line, long seta FR6 anteromesally of the latter, and pore FR4 even more mesally. Inner part of antennal socket with a small seta FR7, central portion of frontale between antennae with two pairs of small setae (FR8–9) converging anteriad. Nasale with a pair of short stout setae mesally at sides of median tooth and a sensillum situated on based on epistomal lobe on each side (gFR1), pores FR15 absent. Each epistomal lobe with a group of eight setae (gFR2) situated on anterior margin, all setae lanceolate, with pilose inner margin; long seta FR12, shorter seta FR10 and a pore FR14 situated on epistomal lobe anteromesally of antennal socket, pores FR11 and FR13 seta FR9 and anterior margin of head. Parietale with 29 sensilla each ( Fig. 10 ). Dorsal face with posterior portion bearing a row of four short setae and one pore (PA1–5) sublaterally, and a pore (PA6) and a short seta (PA7) mesally. Dorsomesal portion with one moderately long seta (PA12) and one very long seta (PA8), ocular area with one pore (PA10) and one seta (PA11) dorsally, and one short seta (PA9) between stemmata of anterior row, and one seta (PA16) ventrally. Lateral portion with a pore (PA30) posteriorly, three long setae (PA13–14 and PA18) situated in posterior half and two pores (PA15 and PA17) situated more anteriorly. Anterior margin laterally with a pore (PA19) dorsally, long seta (PA20) and short seta (PA21) laterally, and three pores (PA23–25) ventrally; sensilla PA22 either absent, or present as a pore anteriorly of PA21. Ventral portion with four sensilla: short seta PA26 anteriorly, pore PA27 and long seta PA28 at midlength, and pore PA29 posteriorly.

Antenna ( Fig. 13f ). Scape with two pores (AN1–2) situated dorsally and three pores (AN3–5) situated along distal margin on lateral, mesal and ventral faces; pedicel with one pore (AN6) dorsally in distal half of sclerotized area, two short setae (AN10–11) situated mesally and three short setae (AN7–9) situated laterally below antennal sensorium (SE1), AN7 large and stout, similar to SE 1 in shape. Sclerotized portion of flagellum lacking sensilla, apical group of sensilla (gAN) bearing several moderately long and short setae.

Mandible with 9 sensilla ( Fig. 13b ). A short long seta (MN1) situated in basal half of outer face, two pores (MN2–3) on dorsal surface ca. at midlength, a pore (MN4), a short seta (MN5) and a small pore (MN6) subapically on inner face.

Maxilla ( Figs 14e–f ) with one short seta ( MX 1) situated ventrally on cardo. Stipes with five moderately long setae on inner surface: MX 7 situated subbasally, MX 8–11 in distal third. Ventral surface with two pores ( MX 3 and MX 4) and one very long ( MX 5) and one short seta ( MX 6). Palpifer with a long seta ( MX 16) mesally close to base, two short setae ( MX 13–14) and one pore ( MX 12) situated along distal margin; situated distally on lateral surface, MX 14 ventrally of MX 16; distal margin ventrally with a seta ( MX 13) and a pore ( MX 12). Base of inner appendage with one pore ventrally ( MX 15) and one dorsally ( MX 17). Inner appendage (gAPP) with one moderately long seta and several very short setae apically. Palpomere 2 with one tiny seta ( MX 27) basally and one pore ( MX 18) at midlength. Palpomere 3 with a series of sensilla on distal margin ( MX 20–23). Palpomere 4 with a short basal seta ( MX 24) and two digitiform sensilla situated subapically. Apical membranous area with short sensilla (gMX).

Labium ( Figs 10a , 13g –h ). Submentum with one pair of long setae (LA1), LA2 absent. Mentum with a pair of pores (LA4) and pair of short setae distally on ventral surface. Prementum ventrally with a pair of minute setae (LA5) basally, and a pair of pores (LA7) and a pair of short setae (LA6) distally below articulation of labial palp; dorsal surface with one pair of basal pores (LA8) basally in membranous area, anteromedian portion between palpal bases with two pores (LA9, LA?12) and a pair of setae (LA10). Palpomere 1 with one tiny seta (LA13) basally and a pore (LA14) on intersegmental membrane, palpomere 2 with a subapical pore (LA15) and additional digitiform sensilla. Apical membranous field with multiple short setae.

Thorax ( Figs 8c–d , 15e–f ). Proscutum with 15 setae and 7 pores on each half situated in three transverse rows; all setae trichoid, pores usually situated close to seta articulation. Ventral portion with two long setae on anterior part of each precoxal sclerite, and a pair of setae situated between procoxa in a membranous area. Lateral portion with a one minute seta behind procoxal articulation. Meso- and metanotum with sensilla arranged in 4 longitudinal rows; each half of mesonotum with 13 setae and 3 pores (2 of them situated next top setal articulation), each half of metanotum with 11 setae and one pore situated next to articulation of posteromesal long seta. Ventral portion of meso- and metathorax with one small sclerite mesally, each with one pair of short setae.

Metathoracic leg ( Figs 15b–c ). Coxa with long setae on a ridge anteriorly above trochanter articulation, and a row of short setae more proximally of articulation. Trochanter with a series of elongated pores ca. at midlength on both anterior and posterior surface, two short setae and one pore on anterior face, three setae posteriorly, and one long seta on posterior face. Femur with 8 short setae and one pore; 4 setae and one pore on frontal surface, four setae on posterior surface. Tibiotarsus with an oblique row of three moderately long setae on anterior and posterior face, distal portion with four trichoid setae around claw articulation. Claw bisetose; setae minute, situated in proximal third of claw length.

Abdomen ( Figs 8i–j , 15e–g, 15j ). Each abdominal segment with four longitudinal rows of sensilla serially homologous with those of thoracic segments; first three mesal rows situated on dorsal sclerite, lateralmost series situated on dorsolateral sclerite. Lateral sclerite with one long and one short seta. Medioventral sclerite with three short setae on each side, lateroventral sclerites each with one short seta. Tergite of segment 9 with 7 sensilla on each side, posterolateral seta very long. Urogomphus with two sensilla (one dorsal, one ventral) on segment 1 and 2 each, segment with with long terminal seta only.

Figures

Fig. 8. Immature stages of Lihelophorus. a–d – head and prothorax of first instar larvae: a–b – H. (Lihelophorus) lamicola Zaitzev, 1908 (a – dorsal; b – ventral); c–d – H. (Lihelophorus) yangae sp. nov. (c – dorsal; d – ventral). e–f – egg cases: e – H. (Lihelophorus) lamicola Zaitzev, 1908; f – H. (Lihelophorus) yangae sp. nov.; g–j – abdomen with spiracles containing air bubbles: g–h – H. (Lihelophorus) lamicola Zaitzev, 1908 (g – tracheal gills and its tracheal system; h – detail of tracheal branching around abdominal spiracle); i–j – H. (Lihelophorus) yangae sp. nov. (i – detail of tracheal system around abdominal spiracles; j – tracheal system of abdomen). Abbreviations: sp – spiracle; trg – tracheal gill.

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).

Fig. 10. Head capsule of the first instar larva of Helophorus (Lihelophorus) yangae sp. nov. a – ventral view; b – dorsal view; c – lateral view.

Fig. 12. Labroclypeus and epistome of larvae of Lihelophorus and Helophorus s.str. a–b – H. (H.) liguricus Angus, 1970 (a – dorsal view; b – ventral view); c–d – H. (Lihelophorus) yangae sp. nov. (c – dorsal; d – ventral); e–f – H. (Lihelophorus) lamicola Zaitzev, 1908 (e – dorsal; f – ventral).

Fig. 13. Head appendages of larvae of Lihelophorus and Helophorus s.str. a–d – mandibles in dorsal view: a – H. (H.) liguricus Angus, 1970 (left mandible); b – H. (Lihelophorus) yangae sp. nov. (left mandible); c–d – H. (Lihelophorus) lamicola Zaitzev, 1908 (c – left mandible; d – right mandible). e–f – left antenna in dorsal view: e – H. (H.) liguricus Angus, 1970; f – H. (Lihelophorus) yangae sp. nov. g–j – labium: g–h – H. (Lihelophorus) yangae sp. nov. (g – ventral; h – dorsal); i–j – H. (Lihelophorus) lamicola Zaitzev, 1908 (i – ventral; j – dorsal).Abbreviations: mp – mandibular penicillus; rt – retinacular tuft.

Fig. 14. Head appendages of larvae of Lihelophorus and Helophorus s.str. a–b – labium of H. (H.) liguricus Angus, 1970 (a – ventral; b – dorsal). c–h – maxilla: a–d – H. (H.) liguricus (c – ventral; d – dorsal); e–f – H. (Lihelophorus) yangae sp. nov. (e – ventral; f – dorsal); g–h – H. (Lihelophorus) lamicola Zaitzev, 1908 (g – ventral; h – dorsal).

Fig. 15. Thorax and abdomen of Lihelophorus and Helophorus s.str. a–d – metathoracic legs (a – H. (H.) liguricus Angus, 1970, frontal view; b–c – H. (Lihelophorus) yangae sp. nov.(b – frontal; c – posterior); d – H. (Lihelophorus) lamicola Zaitzev, 1908). e–f – thorax and first abdominal segments of H. (Lihelophorus) yangae sp. nov. (e – lateral view; f – dorsal view). g–h – abdominal segments (dorsal and ventral views): g – H. (Lihelophorus) yangae sp. nov.; h – H. (Lihelophorus) lamicola Zaitzev, 1908. i–j – abdominal segment 9 and urogomphi: i – H. (H.) liguricus Angus, 1970; j – H. (Lihelophorus) yangae sp. nov.Abbreviations:abd1 – abdominal segment 1; msth – mesothorax; mtth – metathorax; pth – prothorax; sp – spiracle.