Polycesta plana Nelson, 2000

Nelson, G. H., 2000, Polycesta Plana Nelson, A New Species From Baja California Sur, Mexico (Coleoptera: Buprestidae), The Coleopterists Bulletin 54 (2), pp. 263-265 : 263-265

Polycesta plana Nelson , new species

( Fig. 1 )

Diagnosis. Bronzy­black in color; head with frontovertex feebly convex, without median carina; antennomeres longer than wide; pronotum with disk feebly convex without evident impressions, almost twice as wide as long; elytra without scutellar costae, intervals two, four, six and eight prominent; strial punctures small; abdominal sternum one shallowly, longitudinally concave, posterior margin broadly shallowly lobed; tarsomeres three and four with broad membranous lobes beneath.

Description, Holotype Female. Head with frontovertex feebly convex, without median carina, slightly impressed between antennae; surface a mixture of irregular smooth raised areas and moderately large deep punctures that are smaller on vertex; clothed with long, erect, slender, white, hair­like setae; antennae slender, piceous, antennomeres longer than wide, serrate from antennomere 4, 11 oval; clypeus shallowly, triangularly emarginate.

Pronotum 1.9 × wider than long, sharply margined laterally, narrowest at acute anterior angles, strongly expanded at middle, then convergent to rectangular posterior angles; anterior margin deeply arcuately emarginate; posterior margin with rounded lobe at middle; disk feebly convex, flattened medially, slightly impressed posteriorly in midline, slightly flattened laterally; surface moderately densely punctate on broad median area bordered by shiny (except along dull posterior margin) less densely punctate area, lateral parts densely punctate with punctures confluent; punctate areas with sparse, rather long, semierect, slender, hair­like setae. Scutellum small, parallel­sided, rounded apically, surface slightly concave, glabrous, impunctate.

Elytra slightly broader than pronotum, slightly more than four times longer than pron­

1 Present address: 1308 NW Hawk Creek, Blue Springs, MO 64015­1787 U.S.A.

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otum; humeri slightly prominent; lateral margins weakly widened to apical one third, then arcuately converging to truncately rounded apex; margin with moderately large tooth at apical one eighth and smaller teeth more apically; epipleurae sulcate with small tooth at level of metacoxae; disk of each elytron with four prominent smooth costae corresponding to intervals two, four, six and eight, prominence of costae becomes less from medial to lateral; medial costa most prominent and straight, broad toward base, becoming cristate apically; second costa weakly sinuate, also broader toward base; third and fourth costae continue from humeral umbone to near apical eighth; striae with row of close­set moderate punctures, non­costate intervals with moderately dense slightly smaller punctures, punctures more dense laterally and apically; with few inconspicuous, short, semierect, white setae.

Ventrally, punctures dense laterally, deep on prosternal areas, becoming shallow more posteriorly, with medial areas of thoracic sterna and first abdominal sternum smooth, with few scattered fine punctures; punctate areas moderately clothed with short white setae; prosternum with anterior margin weakly bisinuate; metasternum with median sulcus; first abdominal sternum broadly, weakly longitudinally concave, and hind margin broadly lobed; hind margins of sterna two, three and four straight; last visible abdominal sternum triangular, apex narrowly rounded; tarsomeres three and four with broad membranous lobes beneath.

Length, 18.0 mm; width, 7.5 mm.

Types. Holotype female and one paratype female (Essig Museum of Ento­ mology), Mexico, Baja California Sur, Sierra de La Laguna , 27.2 km ENE Todos Santos, 1,800 m elev., 12/ 18­XII­1979, J. Doyen, W. Tschinkel. The paratype is similar to the holotype, except 1 mm shorter and missing head, right mesotarsus and left metatarsus.

Nothing is known about the host for this species, nor about its geographic range, since the holotype and paratype are the only specimens available.

Comparisons. This species does not fit well into any of the subgenera proposed by Cobos (1981). In size, color and elytral costate pattern P. plana resembles P. elata LeC.; however, in pronotal shape and proportion to elytra, it resembles P. crypta Barr. The surface configuration of the pronotum is more even than among other North American species, including the recently described P. constrictinotum Westcott (1998:21) , and the strial punctures are distinctly smaller than in other species, except for P. flavomaculata Nelson. It can be fit into the key to the species presented by Barr (1949:11) as follows:

3. Pronotum without distinct depressions, at most the disk may be flattened; third and fourth tarsomeres with membranous lobes beneath ---------------- 3b Pronotum with a broad median and narrow lateral depressions behind middle; only fourth tarsomeres with membranous lobes beneath ---------- 5

3b. Elytra with distinct scutellar costae ------------------------------------------------------------------- 4 Elytra without scutellar costae ------------------------------------------------- P. plana , n. sp.

Etymology. The specific name refers to the rather even surface of the pronotum.

Figures

Fig. 1. Holotype, Polycesta plana Nelson, dorsal view (photograph by Richard Worth, Salem, Oregon).