Cymindis (Pinacodera) chevrolati

Hunting, Wesley M., 2013, A taxonomic revision of the Cymindis (Pinacodera) limbata species group (Coleoptera, Carabidae, Lebiini), including description of a new species from Florida, U. S. A., ZooKeys 259, pp. 1-73 : 46-48

Cymindis (Pinacodera) chevrolati complex Figs 30-41

Diagnosis.

Diagnosis. Dorsal surface of the pronotum and elytra entirely black in combination with the notably deeper, more irregular single row of punctures in each elytral interval, distinguish members of the chevrolati complex from all other species in the limbata species group.

Description.

Color (Fig. 30, 32-33). Dorsum of head black to rufo-piceous; dorsum of pronotum and elytra black; antennae rufo-piceous to rufo-testaceous; palpi rufo-testaceous; elytral epipleura, ventral thoracic sclerites, and abdominal sterna rufo-piceous to piceous; legs piceous.

Microsculpture. Head capsule and pronotum smooth, microlines not evident at 50 ×. Elytra with mesh pattern isodiametric, microlines shallow to not apparent at 50 ×.

Macrosculpture and pilosity. Head capsule with evenly scattered setigerous punctures on dorsal surface from constriction of neck extended anteriorly toward clypeus. Prothorax ventrally with fine setigerous punctures extended from lateral margin of coxal cavity to apex of intercoxal process. Elytra with striae moderately impressed and punctulate throughout length; intervals slightly convex, single irregular row of ~30-45 punctures within each interval. Abdominal sterna with pilose punctures throughout, setae increased slightly in length toward baso-lateral margins.

Fixed setae. Two pairs of supraorbital setae; clypeus with two lateral setae. Labrum with six setae along apical margin. Pronotum with two to five setae along each margin. Elytra with two seta in stria 3 and one beyond apex of stria 3; one setae at apex of interval two; 15-17 umbilical setae;two setae on each of abdominal sterna III to VI; 4-8 setae along apical margin of sternum VII (Fig. 3).

Luster. Head capsule and pronotum glossy; elytra glossy to slightly glossy, ventral thoracic sterna and abdominal sterna glossy.

Pronotum (Figs 30, 31A-B, 32-33). Anterior and posterior transverse impressions shallow; median longitudinal impression shallow; posteriolateral angles from almost right angled to almost rounded; posterior margin slightly lobate.

Head (Figs 30, 32-33). Eyes and mouthparts typical for Cymindidina .

Elytra (Figs 30, 32-33). Humeri narrowly rounded, typical for subgenus Pinacodera ; striae moderately impressed; lateral margin smooth, rounded and widened preapically; elytral apices truncate.

Hind wings (Fig. 39). Brachypterous, somewhat shortened to markedly short.

Legs. Males with adhesive vestiture ventrally, two rows of squamo- setae on tarsomeres 1-4 of foreleg and 1-3 of middle leg.

Male genitalia. Phallus anopic, cylindrical (Fig. 34A-C) ventral surface slightly curved. Endophallus with a slightly curved endophallic plate (ep) ( Lindroth 1969: 1080-1081) apically. Endophallus with or without microtrichial patch (mp) (Fig. 34, 36) on basal lobe of everted sac.

Female genitalia. Gonocoxite 2 (gc2) (Fig. 35) short and stout (Fig. 35A2) to long and narrow (Fig. 35B2). Internal genitalia with long cylindrical spermatheca (sp), associated spermathecal gland (sg), and spermathecal diverticulum (sd) located at base of spermathecal gland duct (sgd).

Geographical distribution.

The chevrolati complex is known from all the major mountain systems of Mexico north of the Isthmus of Tehuantepec (Fig. 41). It is also known from the Pacific Tres Marias islands.

Chorological affinities.

The geographical range of the chevrolati complex overlaps the range of one other member of the limbata group ( Cymindis punctigera punctigera LeConte) and the ranges of several species of the latiuscula group ( Hilchie and Ball in preparation).

Taxonomic composition.

Three species are included in this complex: Cymindis chevrolati Dejean; Cymindis laevior (Bates); and Cymindis ruficornis (Bates).

Overall body length. Twenty individuals (f=10, m=10) from state population samples of each species in the chevrolati complex were compared (Fig. 38). In each species males are shorter on average then females. Overall body length between Cymindis chevrolati from Durango and Cymindis laevior from Oaxaca, while statistically significant, was not useful taxonomically because of extensive overlap in both males and females.

Hind wing length. The three species in the chevrolati complex are brachypterous, showing metathoracic wing reduction, from slight (Fig. 39B) to extensive (Fig. 39A). Population samples (Fig. 40) were measured to determine possible trends in wing length. Overall, wing length (Fig. 40) of Cymindis chevrolati is the most variable of the three species both between and within populations. Of individuals examined, Cymindis laevior had the lowest variation throughout its range, though a slight decrease in length is observed from north to south. Specimens of Cymindis ruficornis had the shortest average wing length.

In the range of distributional overlap between Cymindis chevrolati and Cymindis laevior , wing length serves as a diagnostic character between the two species in Hidalgo (Fig. 40). In populations from Puebla, however, some overlap does occur.

Metepisternum reduction is associated with wing reduction in Carabidae ( Darlington 1943). Cymindis chevrolati has a metepisternum that is 1.66 to 2.00 × longer than wide, Cymindis laevior is 1.40 to 1.67 × longer than wide and Cymindis ruficornis is 1.35 to 1.45 × longer than wide. This is strongly correlated with the reduction of wing length observed in chevrolati complex members.

Several hypotheses have been proposed for the evolution of brachyptery in insects ( Darlington 1943, Kavanaugh 1985, Liebherr and Hajek 1986). Cymindis laevior and Cymindis ruficornis (the postulated sister group and closest relative to Cymindis chevrolati ) have reduced wings that can be explained as a result of high altitude occurrence and relatively stable montane habitat. Cymindis chevrolati is also found almost exclusively at similar elevations in montane habitats but has a much greater range in wing length. It is unclear what selective pressures may be affecting wing length in Cymindis chevrolati . No geographical trends are apparent.