Hydrodessus imparilis, Miller, Kelly B., 2016

Miller, Kelly B., 2016, Revision of the Neotropical diving beetle genus Hydrodessus J. Balfour-Browne, 1953 (Coleoptera, Dytiscidae, Hydroporinae, Bidessini), ZooKeys 580, pp. 45-124 : 75-78

Taxon classification Animalia Coleoptera Dytiscidae

Hydrodessus imparilis sp. n. Figs 17, 42

Type locality.

Ecuador, Provincia de Napo, Limococha on Rio Napo, 0.737°S 78.111°W.

Diagnosis.

This species is dorsally largely red with the pronotum orange and the elytral apex, lateral margins, and a moderately well-defined macula at about 2/3 length of elytron (Fig. 17A). The lateral margin is more broadly orange near the humeral angle (Fig. 17A). Also, there are very weakly-defined longitudinal fasciae indistinctly present on the anterior half of the elytron (Fig. 17A). The prosternal process has well-developed lateral lobes anteriorly (Fig. 16C). The metaventrite carinae are together strongly constricted immediately posterad to the metaventral process and are strongly divergent posteriorly (Fig. 16C). The male median lobe is elongate triangular basally with a sharp bend at base of apical portion (Fig. 16D). The apical portion is slender and weakly curved to near apex which is very slender and distinctly sinuate with the apex sharply pointed (Fig. 16D). The median lobe in ventral aspect is subparallel but bilaterally asymmetrical with the apex obliquely truncate (Fig. 16E). The lateral lobe is broadly triangular with the apex obliquely truncate (Fig. 16F). There are two series of setae, apically and along the dorsal margin (Fig. 16F).

Description.

Measurements. TL = 2.9 mm, GW = 1.3 mm, PW = 1.1 mm, HW = 0.8 mm, EW = 0.5 mm, TL/GW = 2.2, HW/EW = 1.6. Body shape elongate, narrow, apically pointed, lateral margins slightly, evenly discontinuous between pronotum and elytron (Fig. 16A).

Coloration (Fig. 16A). Head yellow-red. Pronotum yellow. Elytra yellow-red, with diffuse, small yellow maculae anterolaterally and apicomedially and apex yellow (Fig. 16A). Antennae, palpi and legs yellow. Venter red-brown, lighter on epipleuron.

Sculpture and structure. Head broad, anterior clypeal margin broadly rounded; surface shiny with many fine punctures throughout; eyes small. Pronotum narrow, widest at posterior margins, lateral margins weakly curved (Fig. 16A); lateral bead very fine; surface medially similar to head, laterally shiny, irregularly rugulose. Elytra elongate, apically pointed, laterally very broadly curved (Fig. 16A); lateral carina distinctive, but very short, about 1/8 length of elytra (Fig. 16B); surface covereed with fine punctation. Prosternum medially slightly tectiform, setose; prosternal process moderately broad, widest at anterior lateral lobes, lateral margins slightly converging to rounded, thickened apex, with prominent lateral carinae and medial, longitudinally impressed area (Fig. 16C). Legs with surfaces covered with fine punctation; pro- and mesotibiae broad; metatibia with posteroapical brush of setae distinctive; metatrochanter slightly offset, apex slightly flattened and narrowly rounded; metacoxa covered with fine punc tation; metacoxal lines moderately separated, evenly divergent anteriorly (Fig. 16C). Abdomen covered with fine punctures; ventrite VI apically rounded.

Male genitalia. Median lobe bilaterally asymmetrical, in lateral aspect with basal region elongate subtriangular, abruptly curved medially, slightly curved in apical half, gradually expanded along ventral margin, apically sinuate with apex abruptly narrowed and apex pointed (Fig. 16D); in ventral narrow basally, lateral margins broadly curved, left margin more strongly curved, apex obliquely truncate (Fig. 16E). Lateral lobe broad, ventral margin broadly curved, dorsal margin slightly curved, apically narrowed with apex obliquely subtruncate, apex with series of setae and dorsal margin with medial series of setae (Fig. 16F).

Female genitalia. Not examined.

Sexual dimorphism. Female not examined.

Variation. Only a single specimens of this species was examined.

Etymology.

This species is named imparilis, Latin for “unequal,” for the the bilaterally asymmetrical male median lobe.

Distribution.

This species is known only from the type locality in Provincia de Napo, Ecuador (Fig. 42).

Habitat.

The single known specimen was collected at a black light.

Specimens.

The male holotype is in FSCA labeled, "ECUADOR Napo Prov. Limococha On Rio Nap BLT 10.xi.1974 BADrummond III/ Hydrodessus imparilis Miller, 2016 [red label with black line border]."