Himalcercyon Hebauer, 2002

Jia, Fenglong, Liang, Zulong & Fikacek, Martin, 2020, A review of Himalcercyon stat. nov., with description of a new species from the Chinese Himalaya and an updated key to Asian genera of Megasternini (Coleoptera, Hydrophilidae), Deutsche Entomologische Zeitschrift 67 (1), pp. 35-49 : 35

publication ID	https://dx.doi.org/10.3897/dez.67.50078
publication LSID	lsid:zoobank.org:pub:56BB973D-BE4E-47AE-BC98-C1F1151C41C4
persistent identifier	https://treatment.plazi.org/id/30622CFE-27A8-5CD4-9D8E-02EEAA077CDF
treatment provided by	Deutsche Entomologische Zeitschrift by Pensoft
scientific name	Himalcercyon Hebauer, 2002
status	stat. nov.

Treatment

Himalcercyon Hebauer, 2002 View in CoL stat. nov. Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Cercyon (Himalcercyon) Hebauer, 2002: 39.

Type species.

Cercyon (Himalcercyon) mirus Hebauer, 2002.

Diagnosis.

Dorsal surface pubescent; anterior margin of clypeus rounded; frontoclypeal suture not forming transverse ridge between eyes; eyes small, separated 5-6 × the width of one eye; prosternum strongly carinate medially, without ridge demarcating median portion from lateral portions (Figs 2D View Figure 2 , 3B View Figure 3 ); antennal grooves distinct, well demarcated laterally, not reaching lateral margins of prothorax (Figs 2D View Figure 2 , 3B View Figure 3 ); mesoventrite bearing hydrofuge pubescence; mesoventral elevation arrowhead-shaped, widely attaching metaventral process (Figs 2F View Figure 2 , 3C View Figure 3 ), cavities for reception of procoxae ending far anterior to mesocoxae (Figs 2F View Figure 2 , 3C View Figure 3 ); metaventrite with a pentagonal posteromedian glabrous area weakly projecting anteriorly between mesocoxae; femoral lines absent; anterolateral transverse arcuate ridge absent (Fig. 2E View Figure 2 ); each elytron with 10 striae (Figs 1A, B, E, F View Figure 1 , 3H View Figure 3 ); first abdominal ventrite carinate throughout (Fig. 2A View Figure 2 ); last abdominal ventrite with a glabrous apical area (Fig. 2A View Figure 2 ); median lobe deeply inserted into phallobase (Fig. 1C, G View Figure 1 ); median portion of sternite IX tongue-shaped (Fig. 1D, H View Figure 1 ).

Redescription.

Body broadly oval and moderately convex; body outline not interrupted between pronotum and elytra.

Head. Excised in front of eyes laterally, antennal base exposed. Labrum concealed under clypeus, not exposed dorsally. Clypeus not deflexed, truncate anteriorly, without anterolateral extensions; anterior margin narrowly beaded. Frontoclypeal suture obsolete, only visible as impunctate bar. Frons with even surface. Eyes rather small, rounded, projected laterally; interocular distance ca 5-6 × the width of one eye in dorsal view. Dorsal punctation of head consisting of punctures each bearing a long seta. Maxillary palpus slightly longer than half of width of head, with ventral sucking disc in male; palpomere 2 strongly swollen, longer than palpomere 3; palpomere 4 symmetrical, slightly shorter than palpomere 2, but longer than palpomere 3. Mentum ca 2.1-2.4 × as wide as long, trapezoidal, anterior margin not emarginate medially (Figs 2B View Figure 2 , 3A View Figure 3 ). Labial palpomere 3 slightly longer and as broad as palpomere 2, symmetrical. Gula well developed throughout, wide posteriorly, moderately narrowed anteriorly. Antennae with nine antennomeres, ca 0.7 × width of head; scape a little longer than antennomeres 2-6 combined; club compact, pubescent, ca 2 × as long as wide (Fig. 3D View Figure 3 ), slightly longer than scape.

Prothorax. Pronotum relatively short and transverse, widest at base; surface smooth, punctation consisting of setiferous punctures, all punctures of the same size and shape; transverse series of punctures along posterior margin absent. Prosternum well developed, slightly tectiform, strongly carinate medially, without elevated median portion or ridge demarcating median portion from lateral parts (Figs 2D View Figure 2 , 3C View Figure 3 ); antennal grooves distinct, well demarcated, arcuate laterally, not reaching lateral margins of prothorax (Figs 2D View Figure 2 , 3B View Figure 3 ). Prosternal process reaching midpoint of procoxae, not bifurcate apically (Fig. 2D View Figure 2 ).

Mesothorax. Mesoventrite fused to mesepisterna, bearing hydrofuge pubescence; median portion abruptly raised in posterior half to form arrowhead-shaped elevation (Figs 2E, F View Figure 2 , 3C View Figure 3 ), its surface pubescent; cavities for reception of procoxae ended well before mesocoxae (Figs 2E, F View Figure 2 , 3C View Figure 3 ). Each elytron with 10 punctate striae (Figs 1A, B, E, F View Figure 1 , 3H View Figure 3 ), striae sharply impressed. Interval punctation consisting of setiferous punctures (Fig. 3G View Figure 3 ). Scutellar shield small, triangular.

Metathorax. Metaventrite moderately raised medially, forming a bare pentagonal area weakly projected anteriorly between mesocoxae (Figs 2E View Figure 2 , 3F View Figure 3 ); lateral portions with coarse punctures, bearing fine hydrofuge pubescence (Fig. 2E View Figure 2 ). Anterolateral ridge absent; femoral lines absent (Fig. 2E View Figure 2 ). Metepisterna subparallel, ca 6.5 × as long as wide. Hind wings well developed, ca 2.4 × as long as wide; r-m-crossvein rising from base of radial cell; cubital spur rising from apex of M-Cu loop; m-crossvein vestigial; basal cell elongate, wedge cell absent; anal lobe weakly developed.

Legs. Coxae partly with hydrofuge pubescence, mesocoxae moderately separated (Fig. 2A View Figure 2 ). Femora with tibial grooves demarcated by ventral and dorsal ridges; ventral face of pro- and mesofemora glabrous, metafemora with fine microsculpture consisting of transverse lines. Tibiae weakly, gradually widened from base to apices, with fine and sparse lateral spines. Tarsi with five tarsomeres, with dense and short setae ventrally. Meso- and metatarsi with tarsomere 1 ca 2 × as long as tarsomere 2 (Fig. 3E View Figure 3 ), tarsomere 5 slightly shorter than tarsomere 1; claws small and moderately curved (Fig. 3E View Figure 3 ).

Abdomen with five ventrites covered by fine hydrofuge pubescence; ventrite 1 2 × as long as ventrite 2, strongly carinate throughout (Fig. 2A View Figure 2 ); posterior margin of ventrite 5 simply rounded, with an apical glabrous area. Aedeagus (Fig. 1C, G View Figure 1 ) of the Cercyon type, i.e. with median lobe reaching deeply into phallobase in natural position; parameres ca 2 × as long as phallobase, with transversely bent apices; phallobase with asymmetrical basis (manubrium). Median part of sternite IX not reduced, forming a broad tongue-shaped structure (Fig. 1D, H View Figure 1 ).

Discussion.

Hebauer (2002a) proposed Himalcercyon as a subgenus of Cercyon , mentioning that it corresponds to Cercyon in all characters except for the shape of the mesoventral plate. The form of the mesoventral elevation is one of most important generic characters in the Megasternini , and clearly differentiates both Himalcercyon species from all other members of the genus Cercyon . Both species of Himalcercyon are very similar to each other in all important characters and in the general form of male genitalia, indicating that they are likely closely related. Moreover, both species occur in the Himalayas. All of this supports Himalcercyon as a monophyletic clade that differs from Cercyon , as well as other megasternine genera, in the character currently considered as crucial at the generic level. For this reason, we elevate Himalcercyon to genus rank. See Diagnosis for the characters distinguishing Himalcercyon from other megasternine genera, and the identification key for a comparison of Himalcercyon with other Asian Megasternini .