Crostis boreas, Prena & Anderson, 2022

Prena, Jens & Anderson, Robert S., 2022, The genus Crostis Casey (Coleoptera: Curculionidae: Baridinae) in North America, Zootaxa 5162 (2), pp. 153-162 : 155

Crostis boreas species group

Description. Total length 2.2–3.0 mm; dorsal body form oblong-ovate ( Figs. 1–10 ), L/W elytra 1.06–1.43, with substantial intraspecific variability; lateral body form less deep, L/D of body 2.2–2.6. Integument black, shining, with few white, widely spaced, sparse scales (may be abraded) and finer golden hair-like scales. Rostrum laterally with numerous fine punctures, punctures above scrobe somewhat coalescent forming shallow suprascrobal groove and second shallow sulcus. Antenna with funicle ca. 3× as long as short-ovate club. Pronotum slightly wider than long, length ≥1/2 elytra length, lateral margins linearly converging or subparallel, abruptly narrowed in front, transition to tubular collar subrectangular, tubular region with only single row of shallow widely-spaced punctures, pronotal base bisinuate, disc strongly longitudinally striate, some striae sinuous or discontinuous, enclosing short sections of adjacent striae or elongate punctures, striae separated by narrow, raised, glabrous, glossy lines, midline glabrous, glossy, continuous with adjacent lines in anterior 1/3 giving it branching appearance (e.g., Fig. 11 ); flanks with elongate punctures or completely impunctate, glossy. Prosternum with large, deep subcordate fovea with anterior margin modified to lamellar rim and projected across anterior two thirds of fovea ( Fig. 17 ). Elytra with greatest width at about basal third to middle, apices almost conjointly rounded; striae nearly as wide as interstriae, deep and impunctate; interstriae with single row of microscopic setae in small punctures mingled with sparse, large, scalelike setae in elongate grooves (may be abraded); interstrial ridges and subapical callosity absent. Abdominal ventrites I and II medially impressed in males, flat to very slightly convex in females, punctures of ventrites I and II large, lateralmost areas of ventrite I with 2–4 punctures along length, ventrites I and II with isodiametric microsculpture, ventrite V with slightly more setae in male than female, penis asetose, with body widest in middle or basal half, about 1.7–1.9× as long as wide, slightly convergent towards apex, apodemes about 1.6–2.6× longer than length of penis body, endophallite and attachment of duct without group-specific features.

Three species comprise this species group as follows:

Crostis boreas Prena & Anderson , new species ( U.S.A., Mexico [Querétaro, Tamaulipas])

Crostis boreodes Prena & Anderson , new species ( Mexico [Guanajuato, Michoacán])

Crostis caperata Prena & Anderson , new species ( Mexico [Chiapas])

Figures

FIGURES 1–6. Crostis boreas, dorsal and lateral aspects. 1, 2, elongate male, Texas; 3, elongate female, Querétaro; 4, moderately stout female, Querétaro; 5, 6, very stout male, Querétaro. Scale bars 0.5 mm.

FIGURES 7–10. Crostis boreas species group, dorsal and lateral aspects. 7, 8, C. boreodes, Michoacán; 9, 10, C. caperata, Chiapas. Scale bars 0.5 mm.

FIGURES 11–16. Crostis boreas species group, details of pronotum. 11, 12, C. boreas, Texas; 13, 14, C. boreodes, Michoacán; 15, 16, C. caperata, Chiapas.

FIGURES 17–19. Crostis boreas species group, ventral aspects. 17, C. boreas, prosternum with anteriorly covered fovea; 18, C. boreas, punctation on ventrites; 19, C. boreodes, punctation on ventrites. Scale bars 0.5 mm.