Chaetarthria sp.

Jia, Fenglong, Wang, Shi-shuai & Aston, Paul, 2018, Revision of Chaetarthria Stephens (Coleoptera: Hydrophilidae) in China, with a key to the species in the Oriental Region, Journal of Natural History 52 (37 - 38), pp. 2369-2384 : 2375-2377

Chaetarthria sp.

( Figure 3a–c )

Material examined

2 females [ IZCAS: IOZ(E)20022538; IZCAS: IOZ(E)20022533], GUANGXI: ‘ Napo, Defu , 1440m, 3 .iv .1998, Wen-Zhu Li leg’ . 1 female [ IZCAS: IOZ(E)20022536], same locality as other two, ‘ 1300m, 14 .viii .1998, Tong-Li He leg’ . All data is translated from Chinese .

Description

Size and form. 2.4–2.6 mm. Broadly oval, strongly convex. Elytra slightly longer than wide. Colour. Dorsum black. Labrum same colour as clypeus or slightly lighter, without lighter anterior margin. Maxillary palps uniformly dark reddish brown. Pronotum with posterior angles dark brown ( Figure 3a ), only slightly lighter than disc. Elytra uniformly black ( Figure 3c ). Ventral surface black. Mentum dark brown. Legs black with slightly little lighter tarsomeres; epipleura dark brown. Head. Ground punctation on labrum, clypeus and frons undetectable. Systematic punctures on labrum, frons and clypeus very fine but detectable. Labrum not emarginate anteriorly. Eyes small, slightly protruding, separated by c. 5.5× the width of one eye. Maxillary palps about half as long as width of head, apical palpomere almost symmetrical and longer than penultimate ( Figure 3d ). Labial palps about one-third as long as width of mentum, apical palpomere conical, shorter than 2nd, 2nd palpomere with numerous long setae on inner and outer face. Antennae 8-segmented, scape almost as long as following antennomeres combined, club loosely segmented. Mentum ( Figure 3d ) longer than wide, quadrate, entire anteriorly; with very fine and scattered punctures anteriorly, not punctate medially. Thorax. Pronotum shinning, without distinct anterior angles, lateral margin of anterolateral angle dilated, posterior angles acute; lateral stria present along the entire lateral margin, terminating posteriorly at the hind angle. Pronotal ground punctation undetectable, systematic punctures very fine but detectable. Elytra smooth and shinning, with 4 distinct regular series of punctures, between regular series of punctures with 2 distinct irregular series of punctures ( Figure 3c ), lateral portion with irregular punctures that are coarser than those on disc. Sutural stria reaching half of the elytral length ( Figure 3c ), no series of punctures before sutural stria. Prosternum extremely short, only slightly convex, not carinate. Mesoventrite glabrous, slightly concave, with a median, transverse and lightly arcuate ridge at the level of anterior mesocoxal margin. Metaventrite slightly raised, a little more convex and sparsely pubescent medially. Metepisterna about 4.3× as long as wide, more densely pubescent than metaventrite, almost parallel sided except posteriorly, where inner margin bends smoothly towards outer margin. Procoxae densely pubescent, meso- and metacoxae glabrous. Femora with sharply defined tibial grooves on inner face; Femora stout. Pro- and meso-femora densely pubescent except on the apical extremity; anterior half of metafemora densely pubescent, posterior half glabrous with some coarse punctures ( Figure 3b ), posterodorsal margin densely pubescent. Tibiae slender, hardly flattened. Tarsi with 5 tarsomeres, first metatarsomere shorter than second. Abdomen. Ventrites 1–2 with a large cavity on each side, filled with a hyaline mass supported and covered by a fringe of long stiff yellow setae rising from anterior margin of basal ventrite; first two ventrites carinate medially.

Remarks

This species may be close to C. indica d’ Orchymont, 1920 . It is different from C. indica by black labrum, elytra uniformly black, maxillary palps piceous, ventral surface black, legs black with tarsomeres dark brown, and elytra with distinct punctures apart from the systematic punctures, an arrangement otherwise only known from C. saundersi d’ Orchymont in Oriental region. Because a male specimen is lacking, we do not assign these three specimens to any species.

Distribution

Only known from type locality ( Figure 7 ).

Figures

Figure 3. Chaetarthria sp. (a–b) Habitus (a) lateral; (b) ventral; (c) apical portion of elytra; (d) head and prosternum, ventral. Chaetarthria almorana Knisch. (e–f,h) Habitus: (e) dorsal; (f) lateral; (h) ventral; (g) pronotum, left; (i) elytra.

Figure 7. Distribution of Chaetarthria species in China.