Hymenorus excavatus, Campbell, J. M., 2014

Campbell, J. M., 2014, An unusual suite of sexual characters in three new species of Hymenorus (Coleoptera, Tenebrionidae, Alleculinae) from Guatemala and Mexico, ZooKeys 415, pp. 295-309 : 300-301

Hymenorus excavatus sp. n. Figs 2-3, 10-12, 17-18, 21

Description.

This species is almost indistinguishable from Hymenorus balli and Hymenorus bifurcatus based on non-sexual characters. Only the slight variations in non-sexual characters are described below; full descriptions are given for the male and female characters.

Length 8.0-9.7 mm. Eyes moderately separated (OI of male 18 to 24 and of female 18 to 28).

PI index 66 to 73; sides narrowed from base to apical fourth then evenly curved to slightly concave to truncate anterior margin; median basal fovea more elongate than in Hymenorus balli , extending from base to near middle of disc.

Elytra with punctures of intervals slightly denser than in Hymenorus balli and Hymenorus bifurcatus with 3 or 4 punctures across each interval. Metatarsus with basal segment distinctly longer than segments 2-4 combined.

Male: Venter of anterior tarsi with rudimentary lobes on apex of second segment and densely pubescent pad on basal segment. Posterior femora evenly convex on ventral margin, without carina on outer side. Anterior tarsal claws each with more than 20 teeth. Fifth abdominal ventrite highly modified (Figs 11, 12), broadly, deeply, triangularly impressed from apical margin to basal third; sides of impression sharply carinate. Lobes of eighth sternite (Fig. 21) broadly spoon-shaped, curved medially; outer sides evenly convex, apex of lobes narrowly triangular; inner side of lobes each with short tooth near base. Lobes of ninth sternite (Fig. 21) very short, not extending beyond base of lobes of eighth sternite. Apicale (Figs 17, 18) broad, with sides slightly concave medially; apex truncate; penis narrowly triangular.

Female: Anterior tarsal claws each with 7-10 teeth. Apical third of fifth abdominal ventrite broadly, shallowly, concavely impressed; apical margin broadly convex. Ninth tergite (Fig. 12) with apical margin broadly convex; laterally, slightly truncate medially; heavily sclerotized area covering all of tergite except small, triangular, membranous section medially at base.

Types.

Holotype, male, with labels as follows: 22 km S San Marcos, 5000', IX-3-1965, JM Campbell/ HOLOTYPE ♂, Hymenorus excavatus, desig. 2013, JM.Campbell The specimen is deposited in the CNCI.

Paratypes: 13 males, 11 females.

GUATEMALA: Esquintla: 3 km E San Vicente Pacayá, 5500 ft, V.14.1966, JMC (JMCC) 2. San Marcos: 10 km N La Reforma, 4500 ft, IX.4.1964, JMC (CNCI, JMCC) 7; 22 km S San Marcos, 5000 ft, VI.4.1966, X.2.1965, IX.3.1965, JMC (CNCI, JMCC) 11; 20 km S San Marcos, 4500 ft, IX.4.1964, JMC (JMCC) 2. Suchitepéquez: UVG Reserve, S side of Volcán Atitlán, 91° 8.85W, 14° 32.04N, X.9-11.2009, 1543 m, (WBWC) 2.

Etymology.

This species is named excavatus in recognition of the deeply excavate fifth visible male ventrite.

Remarks.

Hymenorus excavatus is similar in external appearance to the two preceding species. Males may be readily identified by the unique sexual modifications of the male fifth abdominal ventrite (Figs 10-11), the eighth and ninth sternites (Fig. 21) and the aedeagus (Figs 17-18). Females are difficult to distinguish externally, but can easily be distinguished by the unique shape (somewhat like an arrowhead) of the ninth tergite (compare Figs 6, 9, and 12). Females can be provisionally distinguished from those of Hymenorus balli by the shallower and broader impression of the fifth abdomnal ventrite.