Spilodiscus skelleyi Caterino & Kovarik, 2001

Caterino, Michael S. & Kovarik, Peter W., 2001, Description Of A New Spilodiscus Lewis, And A Reanalysis Of Spilodiscus Phylogeny (Coleoptera: Histeridae), The Coleopterists Bulletin 55 (2), pp. 134-143 : 135-138

Spilodiscus skelleyi Caterino & Kovarik new species

Type Material (total 9 specimens). Holotype male: ‘‘ FLORIDA: Putnam Co. K. Ordway Pres., 3 mi. E. Melrose, 5–26.IX.1998, P. Skelley, barrier pitfall trap’’ deposited in Florida State Collection of Arthopods . Paratype male (1): ‘‘ FLORIDA: Levy Co., 4 mi. SW Archer on Route 24, 25. III.–6. VI.1999, P. Skelley, coll., ex. Barrier pitfall trap’’; paratype female (1): ‘‘FL: Putnam Co., 3 mi. E Melrose, K. Ordway Preserve, 20­VI­97, P.E.S. [P.E. Skelley]’’/‘‘berlese of litter around deer dung in sand hill meadow’’; paratype female (1): ‘‘ FLORIDA: Levy Co. , 4 mi. SW Archer, 13.X.1996, P.W. Kovarik, collector’’/ ‘‘ex. sand in vicinity of ant nests’’ (see Fig. 3 ); paratype females (2): ‘‘FLOR­ IDA: Levy Co. , 4 mi. SW Archer on Route 24, 25. III.­6. VI.1999, P. Skelley, coll., ex. Barrier pitfall trap’’; paratypes of undetermined sex (3): ‘‘ FLORIDA: Levy Co. , 4 mi. SW Archer on Route 24, 25. III.­6. VI.1999, P. Skelley, coll., ex. Barrier pitfall trap’ ’. Paratypes in United States National Museum (1), Field Museum (1), The Natural History Museum, London (1), Caterino collection (2), and Kovarik collection (3) .

Description. Small [avg. length 2.3 mm; avg. width 1.8 mm; n 5 9]; body round in outline ( Figs. 1–2 ); entirely black with rufescent tinge particularly on elytra.

Frons minutely punctate; frontal stria faintly bisinuate pointing forward at middle; frequently a short transverse striole in the middle of the frontal disk; labrum one­half as long as wide; mandibles convex above, each with bidentate tooth on incisor ( Figs. 3–4 ); antennal club small.

Inner and outer lateral pronotal striae complete; hypomeron setose; prosternal keel longitudinally striate or not; prosternal lobe rounded apically; protibiae acutely bidentate (or rarely unidentate), each tooth with apical spine; posterior surface of protibiae smooth to minutely punctate.

Elytra black or faintly rufescent laterally; outer subhumeral stria absent; inner subhumeral stria faintly impressed at elytral apex or absent; striae 1–2 complete; stria 3 complete or rarely interrupted; stria 4 absent or faintly visible at elytral base; stria 5 absent; sutural stria complete. Meso­ and metatibia with 2 longitudinal series of spines.

Propygidium and pygidium with shallow punctures separated by slightly more than their diameters.

Male genitalia ( Figs. 5–13 ). Aedeagus with basal piece short, approximately one­third tegmenal length; tegmen expanded laterally in apical one­half; lateral arms of median lobe armature feebly sinuate, hooked apically; dorsal projec­ tions of armature two­thirds length of lateral arms, divergent apically; gonopore at base of armature.

Diagnosis. This species’ strongly bidentate protibiae and aedeagus unequivocally identify it as a Spilodiscus and it is easily separated from all other Spilodiscus by its small size, mandibular dentation, and lack of red maculations. Spilodiscus flohri is similar in size to S. skelleyi and has dentate mandibles, but has red maculate elytra and is not known to have prosternal striae. The only other all black Spilodiscus with which S. skelleyi may be sympatric, S. floridanus , is nearly three times its size.

Distribution ( Fig. 14 ). S. skelleyi is known only from 2 locations in northern Florida.

Etymology. We have named this species for Paul Skelley, the collector of the majority of the type series, in recognition of his invaluable and continuing contributions to the knowledge of histerid biology.

Remarks. The habits of S. skelleyi are unknown. Although one paratype specimen was collected near a nest of Pheidole ants, additional sampling has revealed no additional associated specimens (P. Skelley, pers. comm.). We consider it unlikely that this is the beetle’s primary habitat. Pocket gopher ( Geomys pinetus Rafinesque ) and Gopher tortoise [ Gopherus polyphemus (Daudin) ] have likewise been widely surveyed in the same area but have produced no additional specimens. Burrows of mice ( Peromyscus spp. ) are locally common but have not yet been specifically sampled and remain a possibility.

Figures

Figs. 1–4. Spilodiscus skelleyi. 1) Dorsal; 2) ventral; 3–4) anterior. Arrow in fig. 4 indicates the mandibular dentation. Scale bar 5 1.0 mm for Figures 2–3 and 0.5 mm for Figure 4.

Figs. 5–13. Male genitalia of Spilodiscus skelleyi. 5) Dorsal; 6) ventral; 7) lateral views of the 8th abdominal segment. 8) Dorsal; 9) ventral; 10) lateral views of the 9th and 10th abdominal segments. 11) Dorsal; 12) ventral; 13) lateral views of the aedeagus. Scale bar 5 0.5 mm.

Fig. 14. Map of Florida indicating the 2 known localities for Spilodiscus skelleyi.