Coelostoma (Lachnocoelostoma) hajeki, Jia, Fenglong, Aston, Paul & Fikáček, Martin, 2014

Jia, Fenglong, Aston, Paul & Fikáček, Martin, 2014, Review of the Chinese species of the genus Coelostoma Brullé, 1835 (Coleoptera: Hydrophilidae: Sphaeridiinae), Zootaxa 3887 (3), pp. 354-376 : 363-364

Coelostoma (Lachnocoelostoma) hajeki sp. nov.

( Fig. 22 )

Type material. HOLOTYPE: male ( SYSU): GUANGDONG: Nanling, Dadongshan Natural Reserve, 19- 22.iv.2013, Fenglong Jia leg. PARATYPES: 4 males, 5 females and 5 unsexed spec. ( SYSU), same data as holotype; 1 male, 11 spec. ( NMPC): Nanling National Nature Reserve, Dadongshan, shallow puddle on concrete terrace, 24°55.7ʼN 112°43.6ʼE, 785 m, 18.iv.2013, Hájek & Růžička leg. GUANGXI: 1 male ( NMPC): Longsheng Hot Spring, forested river valley, 25°53.6ʼN 110°12.4ʼE, 360 m, hygropetric, wet rocks at side of the trail along the river, day and night collecting [MF09], 11-14.iv.2013, Fikáček, Hájek & Růžička leg.

Diagnosis. Body size 4.8–5.2 mm. Prosternum moderately carinate medially, with more or less strong dentiform process anteromedially. Head, pronotum and elytra with similar punctation; elytra with lateral portion more or less strongly punctate, without traces of series of punctures laterally. Mesofemora densely pubescent except at extreme apex. First abdominal ventrite with recognizable median carina; last ventrite emarginate and with a row of stout setae apically. Aedeagus ( Fig. 22 ): 1.15 mm long. Median lobe deeply and narrowly emarginated at apex, gonopore as long as wide, situated basally; parameres as long as median lobe, obliquely truncate apically.

Description. Form and Color. Body length 4.8–5.2 mm, width 3.0– 3.2 mm. Body oval, strongly convex. Dorsum black. Labrum, maxillary palpi, labial palpi yellowish to reddish brown, antennae yellowish to reddish brown with dark club. Ventral surface dark ferruginous with reddish pubescence. Femora and tibiae dark reddish brown, tarsi yellow.

Head. Surface with dense and moderately strong punctures. Intervals between punctures smooth, without shagreen and transverse microsculpture on posterior margin. Clypeus truncate anteriorly. Eyes moderately large, separated by ca. 5× the width of one eye, not emarginate anteriorly. Mentum with strong punctures, strongly emarginate anteriorly and depressed on anterior half, without sculpture on depression. Antennae with 9 antennomeres, antennal club loosely segmented. Maxillary palpomere 2 strongly swollen, palpomere 4 slightly asymmetrical, rather longer than palpomere 3. Gula very narrow, glabrous.

Thorax. Pronotum with somewhat finer punctures than on head; anterior margin strongly bisinuate; posterior margin slightly bisinuate; lateral marginal bead reaching posterior corner, not continuing to posterior margin; posterior corner almost rectangular. Prosternum moderately carinate throughout medially, forming a strong fingershape anteromedian spine. Mesoventrite with raised, arrowhead-shaped process, surface pubescent. Metaventrite with strongly raised median portion broadly projecting anteriorly between mesocoxae and abutted to mesoventral process; lateral portions of metaventrite densely pubescent, middle portion more shining, only sparsely pubescent. Metepisterna ca. 5× as long as wide, parallel-sided. Scutellar shield slightly longer than wide, with punctation as on pronotum. Elytra with coarser punctures than on pronotum, lateral and posterior punctures somewhat coarser than those on disc, without traces of series; sutural stria reaching basal half of elytra. Femora with deep tibial groove posteriorly. Mesofemora densely pubescent, except at extreme apex. Metafemora sparsely punctate, with dense microsculpture. Tarsi with long dorsal setae and gold ventral setae. Metatarsi with first tarsomere almost twice as long as second tarsomere, fifth tarsomere almost as long as the third and fourth combined. Claws moderately curved, with a pair of long setae beneath.

Abdomen. Abdominal ventrites densely pubescent. First abdominal ventrite with recognizable median carina; fifth ventrite emarginate and with a row of stout setae apically.

Aedeagus ( Fig. 22 ). 1.15 mm long. Median lobe broadest on basal third, gradually narrowed to apical third, apical third almost parallel, with apex deeply and narrowly emarginated (bilobed), gonopore as long as wide, situated basally; parameres as long as median lobe, subparallel laterally, slightly concave on outer face subapically and slightly oblique truncate apically.

Biology. Hygropetric, collected in a shallow puddle on concrete terrace at night (Guangdong) and on wet rocks at side of the trail along the river (Guangxi).

Etymology. The new species is named in honour of Dr. Jiří Hájek, a beetle taxonomist in the National Museum, Czech Republic, who first discovered this species at the type locality and collaborated with the senior and third authors many times.

Remarks. This species is very similar to C. turnai Hebauer, 2006 . It can be distinguished from the latter by median lobe of aedeagus slightly widening basally (strongly broadened in C. turnai ), the gonopore widely oval (very transversely oval in C. turnai ) and apical emargination of median lobe moderately deep (very deep in C. turnai ); parameres are weakly sinuate laterally (strongly sinuate in C. turnai ) and obliquely truncate apically (not oblique in C. turnai ). The shape of median lobe can be easily distinguished from other species that have bilobed median lobe, such as C. coomani Orchymont, 1932 , C. lazarense Orchymont, 1925 and C. bifidum sp. nov.

Distribution. China (Guangdong, Guangxi).

Figures

FIGURES 15 – 23. Aedeagus of Chinese Coelostoma. 15: C. fallaciosum, 16: C. vitalisi, 17 – 18: C. vividum (17: specimen from Guangdong: Heishiding; 18: paratype from Sumatra: Bengealis), 19: C. orbiculare, 20: C. bifidum sp. nov., 21: C. turnai (specimen from Hunan), 22: C. hajeki sp. nov., 23: C. hongkongene sp. nov.