Eschatomoxys pholeter Thomas and Pape, 2007

López-Guerrero, Irma, 2007, Figs. 30 – 33. Attavicinus monstrosus. 30 in Comparison of Mouthpart Morphology of Three Species of Mexican Oniticellini (Coleoptera: Scarabaeidae: Scarabaeinae) in Relation to Their Trophic Habits, The Coleopterists Bulletin 61 (4), pp. 519-540 : 519-540

Eschatomoxys pholeter Thomas and Pape , new species

( Figs. 1 , 5 , 8A,B )

Form elongate, fiddle-shaped ( Fig. 1 ), apterous. Color uniformly castaneous to piceous, shining (in life with a bluish, waxy bloom). Males: length, 9.3–11.3 mm; width, 4.1–5.1 mm. Females: length, 10.1–11.7 mm; width, 4.3–5.1 mm.

Head. Prognathous, slightly deflexed, dorso-ventrally compressed; subquadrate in dorsal view, cranium about equal length (1.8–2.2 mm) and width (1.9–2.3 mm), greatest width across epistoma. Lateral epistomal margins rounded, converging toward eyes. Median epistomal lobe produced, arcuate, margin serrulate, weakly, broadly emarginated on each side at epistomal suture. Epistomal sutures obsolescent. Supraorbital carina feeble, short, beginning at middle of lateral epistomal lobe, fading above middle of eye; cuticle behind eye smooth. Cranial surface set with shallow punctures on dorsum separated from one another by about two diameters of a puncture, becoming denser to contiguous on sides of head at base, degenerating to wrinkles on venter. Eyes small, oval, anteriorly emarginated to accommodate epistomal canthus; facets in nine horizontal rows, median row longest with eight facets. Posterior margin of eye separated from cervix by distance equal to two and one-half to three times diameter of eye. Labrum retractile, apex broadly emarginated, emargination bristling with marginal setae. Mandibles thick, robust, left side dominant (overlapping right), apex bifid; superior margin with stout angular cusp, somewhat larger on right mandible than left. Maxillary palpus approximately equal in length to first two antennomeres, basal segment longest (apical segment more elongate, slender in 526 male, subsecuriform in female). Mentum hexagonal, surface coarsely punctate. Submentum with large ovoid fossa at middle. Gula rectangular, surface shagreened. Tentorial pits distinct, each connected to cervix by thin sulcus demarcating gula. Antennae filiform, antennomeres slender except basal segment broadened apically and last segment pyriform, acuminate. Third segment longest; fourth to seventh subequal; eighth, ninth and tenth successively shorter until penultimate segment, which is about twice as long as wide; last segment spindle shaped, 1 K times length of penultimate.

Thorax. Pronotum cylindrical, shorter than head, wider (2.1–2.5 mm) than long (1.5–1.9 mm), widest at middle; surface set with shallow punctures dorsally, the latter becoming less defined and more widely spaced laterally, inconspicuous ventrally. Weak lateral margin present in apical fourth behind anterolateral angle, which is obtuse. Base of pronotum constricted with thick, marginal bead demarcating posterior edge. Femora long, clavate; tibiae. tarsi long, slender. Elytra inflated, embracing abdominal venter; surface glabrous, obscurely punctate at base; base slightly wider than apposing pronotal base. Epipleura widest basally, about as wide as metepisternum, gradually narrowing to about third abdominal segment, parallel thereafter, apex about half width at base.

Abdomen. Ovoid in form, widest at middle (4.1–5.1 mm), longer than wide (6.0– 7.7 mm). Surface of abdominal sternites smooth, impunctate. Length of first abdominal sternite from metacoxa to posterior margin about three-quarters length of second; third about two-thirds length of second; fourth about half width of third; fifth about 1 K length of fourth. Males with elongate, ovoid, pubescent fovea at middle of first abdominal sternite.

Genitalia. Male aedeagus 3.2 mm long ( Fig. 8A ); tegmen elongate, spatulate, cleft at apex. Median lobe (penis) extrusible, narrow, elongate, a simple flattened rod acute at apex, its ventral surface narrowly sulcate. Female ovipositor 2.2 mm long ( Fig. 8B ); sclerotized dorsally, open ventrally. Paraproct slightly longer and narrower than coxite; bacula (valvifers) prominent, thick, flattened, sclerotized rods; basicoxites wider and shorter than terminal, triangular gonocoxites; apex of each gonocoxite with digitoid lobe on each side, bearing a small seta-like stylus. Vulva terminating in a pair of digitoid lobes, each ental to and subequal in size to terminal lobe of gonocoxite.

Holotype. Male. ARIZONA: Mohave Co., Grand Canyon N.P., Bat Cave , 29- III-96, R. B. Pape coll. Allotype. Female. Labeled same data as holotype. Paratypes: Three males, one female, labeled same data as holotype; Four males, six females: AZ. Mohave Co., Bat Cave, Gr. Canyon, GRCA Cave SCI-0043, 26- X-01, R. B. Pape (deposited CAS and DB Thomas collection). One female: AZ. Mohave Co. , Eldel Cave , twilight, IX-23-05, J. Judson Wynne col. Three females: ARIZONA: Mohave Co. , Grand Canyon N.P., Rampart Cave , teneb on 7,200 yr old sloth shit .

Etymology. The specific epithet pholeter (Greek) meaning, one who lurks in a hole.

Diagnosis. The new species averages larger in length than the other U.S. species. The smaller eyes differentiate this species from E. wagneri . It differs from E. tanneri and E. wagneri in the configuration of the gula. Presumably the longer head requires strengthening of the tentorial endoskeleton such that the tentorial pits are pronounced and the gula well demarcated by a narrow sulcus on each side, its surface contrastingly smooth compared to the rugose surface lateral to the sulci; whereas in E. tanneri and E. wagneri , with proportionately shorter heads, the gula is obsolete with neither tentorial pits or sulci prominent, and the rugosity of the venter is irregularly continuous towards the midline. The presence of this species in three separate but nearby caves suggests that this species is a troglophile and likely occurs in crevices rich in organic matter such as rodent nests in this surrounding area (see discussion of biology below).

Figures

Fig. 1. Dorsal habitus of Eschatomoxys pholeter.

Figs. 4–5. Eschatomoxys spp. head and pronotum, lateral view. 4) E. wagneri, with relatively large eyes; 5) E. pholetor, with relatively small eyes.

Fig. 8. Genitalia of E. pholeter: A) aedeagus, B) ovipositor.