Plochionocerus gracilis Asiain, Márquez & Morrone, 2007

Asiain, Julieta, Márquez, Juan & Morrone, Juan J., 2007, Phylogenetic systematics of the genera Plochionocerus Dejean and Agrodes Nordmann (Coleoptera: Staphylinidae: Xantholinini), Zootaxa 1584, pp. 1-53 : 16-17

Plochionocerus gracilis Asiain, Márquez & Morrone , sp. nov.

Type material. Holotype, female: “ PANAMA: Chiriqui Prv., 7 km Fortuna Dam, 15–17.V.1996, Wappes Huether & Morris / gift ex J. Wappes / Holotype Plochionocerus gracilis Asiain, Márquez & Morrone, 2007 ” ( FMNH).

Description. Total length 16.0 mm. Body metallic violet-blue.

Head. Rectangular, 1.36 times longer than wide, slightly wider than pronotum (1.08 times); dorsal and ventral surface of head slightly convex ( Fig. 12 ), ventrally with dense, expanded, umbilicate punctures (20–29 in each half of head), arranged in “v” ( Fig. 51 ); first antennomere 1.56 times as long as antennomeres 2+3 combined; second antennomere 0.7 times as long as third antennomere; antennomeres 4–10 slightly transverse, increasing its size toward antennomere 10; apical antennomere 1.38 times as long as wide, as long as two previous antennomeres combined ( Fig. 24 ); mandibles with basal external channel; apical labial palpomere elongate, slightly truncate in apex ( Fig. 44 ).

Thorax. Pronotum 1.51 times as long as wide; shorter than elytra (0.84 times their length); without depressed areas in posterior third. Posterior margin of elytra with clearly visible central notch ( Fig. 59 ). Prosternum almost as long as wide (length/width: 0.91–1.01).

Male unknown.

Comparative notes. This species, known by a single female, has some peculiar characters, shared partially with P. marquezi , like the small, elongate body, and the elongate labial apical palpomere. No other species of this genus has these characters. In Plochionocerus marquezi the head is elongate and narrowed backwards, the labrum has two central, pointed teeth at the anterior margin, and the pronotal hypomeron has fine setae in anterior third; whereas P. gracilis has a rectangular head that is not narrowed backwards, the labrum has two lateral teeth that are smaller than the central teeth, and the pronotal hypomeron lacks setae.

Geographical distribution. Panama.

Etymology. The name refers to the gracile habitus of this small species.

Figures

FIGURES 9 – 16. Lateral view of head: 9, Philonthus testaceipennis; 10, Agrodes elegans; 11, Plochionocerus discedens; 12, P. gracilis; 13, P. humeralis; 14, P. m a rq u e z i; 15, P. simplicicollis; 16, Renda flagellicornis.

FIGURES 48 – 53. Cephalic ventral view: 48, Renda flagellicornis; 49, Philonthus testaceipennis; 50, Plochionocerus simplicicollis; 51, P. gracilis; 52, P. h e r m a n i; 53, P. puncticeps.

FIGURES 20 – 31. Antennae: 20, Philonthus testaceipennis; 21, Renda flagellicornis; 22, Agrodes conicicollis; 23, A. elegans; 24, Plochionocerus gracilis; 25, P. humeralis; 26, P. i g n e u s; 27, P. m a rq u e z i; 28, P. puncticeps; 29, P. re t i c u - laris; 30, P. s p l e n d e n s; 31, P. transversalis.

FIGURES 40 – 47. Maxillary (a) and labial (b) palpi: 40, Philonthus testaceipennis; 41, Renda flagellicornis; 42, Agrodes elegans; 43, Plochionocerus impressipennis; 44, P. gracilis; 45, P. m a rq u e z i; 46, P. simplicicollis; 47, P. puncticeps.

FIGURES 54 – 62. Pronotum: 54, Philonthus testaceipennis; 55, Renda flagellicornis; 56, Plochionocerus simplicicollis; 57, P. reticularis. Elytra: 58, Agrodes spp.; 59, Plochionocerus spp. Midleg: 60, Philonthus testaceipennis; 61, Agrodes spp.; 62, Plochionocerus spp.