Chasmogenus gironae, Glynn & Short, 2021

Glynn, Rachel D. & Short, Andrew Edward Z., 2021, New species and records of Chasmogenus Sharp, 1882 from the southwestern margin of the Guiana Shield (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 5048 (3), pp. 435-443 : 440-441

Chasmogenus gironae sp. n.

Figures 2C–D , 3B , 5C–D , 6

Type Material. Holotype (male): “VENEZUELA, T.F.Amaz. / Cerro de la Neblina / 1.5 km S Basecamp / 0°50’N, 66°10’W / 250 m., 15 Feb. 1985 ”, “In small ponds full/ of dead leaves;/ rainforest ridge/ P. J. & P. M. Spangler,/ R. Faitoute, W. Steiner ” ( MIZA) . Paratypes (36): VENEZUELA: Amazonas: Same data as holotype (36 exs., SEMC, USNM) .

Differential Diagnosis. Among species with the median lobe of the aedeagus and the parameres approximately even in length and a long basal piece, this species is similar in morphology and general form of the aedeagus to C. brownsbergensis Smith & Short, 2020 , but may be distinguished by characters of the median lobe and dorsal coloration of the head. The median lobe of C. gironae bears a rounded triangular apex past the position of the gonopore and a constriction located medially, whereas the apex of C. brownsbergensis is acutely triangular with straight sides and the constriction is situated more distally closer to the gonopore. The coloration of the head of C. brownsbergensis has mesal dark patches on the clypeus and the labrum compared to the uniformly colored head of C. gironae .

Description. Size and color. Total body length 3.4–3.7 mm. Body form elongate oval. Dorsum of head dark brown to very dark brown posteriorly, clypeus and labrum slightly paler ( Fig. 3B ). Pronotum and elytra uniformly very dark brown ( Fig. 2C ). Venter uniformly dark orange-brown to dark brown ( Fig. 2D ). Head. Ground punctation on head fine. Clypeus with anteromedial emargination, which exposes a broadly rounded gap between the clypeus and labrum ( Fig. 3B ). Mentum moderately depressed in anterior half with a triangular to rounded anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine ( Fig. 2C ). Prosternum very weakly to not at all tectiform. Mesoventrite with moderate elevation forming a thin posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths ( Fig. 2D ).

Aedeagus. Aedeagus ( Fig. 5C,D ) with median lobe that bears a single medial constriction situated halfway between base and apex, base and position of gonopore of equal width, tapering past position of gonopore narrowing abruptly to form a rounded triangular apex which is even with the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated ca. half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. half the length of the parameres.

Etymology. This species is named in honor of Dr. Jennifer Girón, for her substantial contributions and dedication to the study of the taxonomy and morphology of the subfamily Acidocerinae and for her valuable mentorship of the first author.

Distribution. Known only from the type locality near the base of Cerro de la Neblina in southern Venezuela.

Biology. Chasmogenus gironae was collected in small ponds full of leaves in lowland rainforest.

Figures

FIGURE 2: Dorsal and ventral habitus of Chasmogenus spp. A–B C. clinatus sp. n. C–D C. gironae sp. n.

FIGURE 3: Dorsal view of heads of Chasmogenus spp. A C. clinatus sp. n. B C. gironae sp. n. C C. inpa sp. n.

FIGURE 5: Aedeagi of Chasmogenus spp. A–B C. inpa sp. n. (both Brazil:Amazonas) C–D C. gironae sp. n. (both Venezuela) Scale bar: 0.20 mm

FIGURE 6: Distribution of new Chasmogenus spp.