Hydrochara loong, Mai & Jia, 2024

Mai, Zuqi & Jia, Fenglong, 2024, A new species of Hydrochara Berthold from China (Coleoptera, Hydrophilidae, Hydrophilini), Zootaxa 5453 (3), pp. 359-368 : 360-367

publication ID	https://doi.org/ 10.11646/zootaxa.5453.3.3
publication LSID	lsid:zoobank.org:pub:FAB7B658-47B0-4507-8D91-1ACC8DB03EAE
DOI	https://doi.org/10.5281/zenodo.11281536
persistent identifier	https://treatment.plazi.org/id/3F077513-FFED-B772-A6A2-FE3AFB8BFD0A
treatment provided by	Plazi
scientific name	Hydrochara loong
status	sp. nov.

Treatment

Hydrochara loong sp. nov.

( Figs 1A View FIGURE 1 , 2 View FIGURE 2 , 3A, C View FIGURE 3 , 4A, C View FIGURE 4 , 5 View FIGURE 5 , 6 View FIGURE 6 , 7 View FIGURE 7 )

Type material examined. Holotype: male (SYSU), “ China: Shaanxi Prov., Hanzhong, Yangxian County, Yangjiagou forestry station (DZđ汉中市洋县杨ẋ沟µ场), 900 m, 33.6467°N, 107.4918°E, 9.VII.2023, Zhao-qi Leng leg.” GoogleMaps Paratypes: 1 female ( SYSU), “ China: Shaanxi Prov., Hanzhong, Yangxian County (DZđ汉中市洋县), 12–15.VII.2017, Yu-chen Zheng leg.” GoogleMaps 1 female (SYSU), “ China: Hubei Prov., Enshi, Chunmuying, Chenjiadadong (À北OiAE椿木ÜĿẋk洞), 1803 m, 30°2’47.1492’’N, 109°47’8.0664’’E, 18.VI.2020, Zi-hao Shen leg.” GoogleMaps

Diagnosis. Length 21.5–23.5 mm. Legs black with tarsomeres dark reddish black; maxillary palps yellowish to reddish brown, not paler at the apical portion of each segment ( Fig. 4A View FIGURE 4 ). Lateral rim of pronotum wider than the diameter of serial punctures near base of elytron. Prosternal carina almost straight and obtusely angulate anteriorly in lateral view ( Fig. 5B View FIGURE 5 ), sometimes with a small blunt tooth anteriorly ( Fig. 5A View FIGURE 5 ). Mesosternal keel dentate anteriorly ( Fig. 5C View FIGURE 5 ). Metasternal keel somewhat flattened longitudinally at posterior end, almost exceeding middle of the first abdominal ventrite ( Fig. 5C, D View FIGURE 5 ). Lateral rim of elytron relatively wide, near base of elytron about equally wide as lateral rim of pronotum ( Fig. 6B View FIGURE 6 ). Elytra without sutural stria; each elytron with 5 distinct rows of systematic punctures; intervals of systematic punctures with 1–2 rows of extremely fine punctures, vaguely impressed ( Fig. 4C View FIGURE 4 ). Fifth abdominal ventrite with a large trapezoidal glabrous patch ( Fig. 5E View FIGURE 5 ). Aedeagus elongate ( Fig. 3A, C View FIGURE 3 ); parameres slender, almost straight from base to apical third, apical third slightly bend inward, apices obtusely pointed; lateral margins of parameres slightly convex medially. Median lobe gradually narrowed from base to apex, reaching apical fifth of parameres; dorsal face of median lobe with a fine median longitudinal groove from base to apex and forming a fine emargination apically ( Fig. 3A View FIGURE 3 ); gonopore oval, situated apically ( Fig. 3C View FIGURE 3 ).

Description. Form and Colour ( Figs 1A View FIGURE 1 , 2A, B View FIGURE 2 ). Body length 21.5–23.5 mm (Holotype: 21.5 mm), width 10.1– 11.5 mm (Holotype: 10.1 mm). Oblong oval and moderately convex. Dorsum black, with feeble dark green metallic sheen in side illumination. Maxillary palps yellowish to reddish brown, slightly darken in apical segment. Labial palps reddish brown. Antennae with antennomeres 1–5 yellowish brown, slightly darkened at the apical portion of pedicel (antennomere 2) and basal portion of intermediate segments (antennomeres 3–5); cupule (antennomere 6) dark reddish brown, club (antennomeres 7–9) black. Ventral surface black in most part. Mentum and labium reddish black to black. Gula reddish black or black (reddish black in holotype). Prosternum reddish black to black, prosternal carina somewhat paler (reddish brown in holotype). Mesoventrite black (holotype with reddish black mesosternal keel). Metaventrite black. Abdominal ventrites black with yellow brown patches on both side of each ventrite. Legs with coxae reddish black to black; femora and tibiae black, tibiae with reddish black to yellowish brown spines. Tarsomeres black and slightly paler in apical tarsomeres, meso- and metatarsomeres with golden swimming hairs.

Head. Dorsal surface with dense fine puncture and distinct systematic punctures. Labrum transverse and emarginate anteriorly, surface with dense fine punctures and a transverse row of systematic punctures near the base. Clypeus with straight anterior margin, systematic punctures of clypeus coarse, arranged into an anteriorly convex arc on each side. Frontoclypeal suture distinct. Eyes large and convex, separated by 4.3× the width of one eye; each bordered medially with arcuate row of systematic coarse punctures (ocular punctures). Antennae 9-segmented, pedicel about 1/2× as long as scape, about equally length as intermediate segments combined; cupule cone-shaped embracing the base of club; club pubescent but without long setae, antennomeres 7 and 8 asymmetrically lunulate, antennomere 9 dorsoventrally compress, of asymmetrical subpentagonal shape. Maxillary palps 4-segmented, approximately the same length as the width of head; the first palpomere very small, palpomeres 2 and 3 long, slightly curved inwards; palpomere 3 ca. 3/4× the length of palpomere 2; palpomere 4 ca. 2/3× the length of penultimate. Labial palps 4-segmented, short; the first and second palpomere very small; palpomere 3 slightly swollen and bearing with several long setae on inner face; palpomere 4 asymmetrical, ca. 2/3× the length of palpomere 3. Mentum subtrapezoid and flat, anterior margin subtruncate; surface with both extremely fine and moderately coarse punctures. Submentum glabrous. Gula pubescent, gena near gula partly glabrous ( Fig. 6A View FIGURE 6 ).

Thorax. Pronotum widest posteriorly, arcuately narrowed anteriad, with fine puncture as on head; each side with short and oblique rows of coarse systematic punctures. Pronotum with anterior and lateral marginal rims, without posterior marginal rim; anterior rim fine, lateral rim of pronotum much wider ( Fig. 6B View FIGURE 6 ). Prosternum strongly tectiform medially, with sharp median carina; prosternal carina pointed posteriorly, almost straight and obtusely angulate anteriorly in lateral view, sometimes with a small blunt tooth anteriorly ( Fig. 5A, B View FIGURE 5 ). Scutellum triangular and large, almost as long as wide, with fine punctures as on pronotum. Elytra with ground punctures as on pronotum, without sutural stria; each elytron with 5 more or less irregular distinct rows of systematic punctures, 1st, 2nd and 4th rows reaching elytral base; 1st rather regular, consists of more closely arranged punctures; 2nd row consists of more dispersed punctures that are relatively irregular; 3th to 5th rows consisting of scattered punctures and more irregular; 3th and 5th rows short, not reaching elytral base. Intervals with 1 or 2 longitudinal rows of extremely fine punctures, vaguely impressed ( Fig. 4C View FIGURE 4 ). Elytral marginal rim relatively wide, near base of elytron about equally wide as lateral rim of pronotum ( Fig. 6B View FIGURE 6 ); rim gradually narrowed posteriorly. Elytral epipleuron oblique. Mesoand metasternum elevated and fused at midline, forming a long sternal keel; sternal keel dentate anteriorly in lateral view ( Fig. 5D View FIGURE 5 ), dent bearing several long setae; sternal keel not distinctly widened at metasternal portion, produced into an obtuse spine somewhat flattened longitudinally posteriorly which almost exceeding middle of the first abdominal ventrite ( Fig. 5C, D View FIGURE 5 ).

Legs. Profemora pubescent along basal margins, with remainder part scattered fine punctures; meso- and metafemora glabrous with denser and coarser punctures. Protibiae with short, densely set spines on outer and apical margins and a similar row of slightly narrower and less densely set spines on front face; two apical spurs slightly curved. Meso- and metatibiae with longitudinal rows of spines. Protarsomeres with spines ventrally and with sparse long setae dorsally; tarsomere 5 ca. 3/4× the length as tarsomeres 1–4 combined ( Fig. 6C, D View FIGURE 6 ); claws of male being strongly curved and hook-like ( Fig. 6C View FIGURE 6 ). Meso- and metatarsomeres with spines ventrally and with dense long swimming hairs dorsally, tarsomere 2 the longest.

Abdomen. Abdominal ventrites with dense pubescence over the entire surface, except for a large trapezoidal glabrous patch on the fifth abdominal ventrite posteromedially; fifth abdominal ventrite evenly rounded ( Fig. 5E View FIGURE 5 ).

Aedeagus ( Fig. 3A, C View FIGURE 3 ). Moderately elongate, parameres slender, about 2× the length of phallobase; parameres almost straight from base to apical third, apical third gradually bending inwards, apices obtusely pointed; lateral margins of parameres straight medially; punctation of parameres fine, moderately distributed. Median lobe gradually narrowed from base to apex, reaching four-fifths of length of parameres; dorsal surface of median lobe sclerotized, with a fine median longitudinal groove from base to apex and a fine emargination apically. Ventral surface of median lobe membranous, apex with a large and oval gonopore, situated apically.

Etymology. The species name ‘loong’, the Chinese totem, a creature of Chinese legend.

Remarks. This new species is larger than all previously known members of the genus. Other species of Hydrochara are between 10.5–19.5 mm in length, while this new species is 21.5–23.5 mm in length. Based on the morphology of the prosternal carina, lateral marginal rims of the pronotum and elytra, and the shape of aedeagus, this species is similar to the East Palearctic species Hydrochara libera and the West Palearctic species H. semenovi (Zaitsev, 1908) . The new species can be distinguished from H. libera by the following characters: larger size (14.0– 17.5 mm in H. libera ), maxillary palps yellowish to reddish brown, not paler at the apical portion of each segment ( Fig. 4A View FIGURE 4 ) (maxillary palps dark piceous with apical portion of each segment slightly paler in H. libera ( Fig. 4B View FIGURE 4 )), rows of fine punctures on both side of rows of systematic punctures vague ( Fig. 4C View FIGURE 4 ) (clearer than H. loong sp. nov. in H. libera ( Fig. 4D View FIGURE 4 )), aedeagus ca. 1.3× as long as that of H. libera , lateral margins of parameres straight medially ( Fig. 3A, C View FIGURE 3 ) (lateral margins of parameres sinuate or slightly concave medially in H. libera ( Fig. 3B, D View FIGURE 3 )), apical portion with a longer arc on inner margin (a short arc on inner margin in H. libera ), gonopore oval ( Fig. 3C View FIGURE 3 ) (gonopore triangular in H. libera ( Fig. 3D View FIGURE 3 )). The new species can be distinguished from H. semenovi by rows of fine punctures on both side of rows of systematic punctures vague (distinct in H. semenovi ), sternal keel not distinctly widened at metasternal portion ( Fig. 5C View FIGURE 5 ) (metasternal portion of sternal keel distinctly widened in H. semenovi ).

Biology. A female was first collected by light trap in an open valley of the Qinling Mountains in 2017 ( Fig. 7C View FIGURE 7 ). Six years later, a male was collected in a pond in the same valley ( Fig. 7A, B View FIGURE 7 ). This species is likely similar to most species of the genus, inhabiting stagnant water with vegetation, adults clearly fly to light. The rest of the biology is unknown.

Distribution. China (Shaanxi, Hubei). Only known from the type localities.