Pumiliofossorum Silvestro & Giraldo

Silvestro, Violeta A., Giraldo Mendoza, Alfredo E. & Flores, Gustavo E., 2015, Pumiliofossorum: A new genus of Scotobiini (Coleoptera: Tenebrionidae) with two new species from Peru, and a revised key for the genera of the tribe, Zootaxa 3986 (4), pp. 461-471 : 462-464

Pumiliofossorum Silvestro & Giraldo , gen. nov.

( Figs. 1–21 )

Type species. Pumiliofossorum moche Silvestro & Flores, sp. nov., present designation.

Etymology. The generic epithet, which means “dwarf digger”, refers to the relatively small sizes of the two known species (the smallest ones currently known in Scotobiini) and the presence of fossorial tibiae. Gender neuter.

Diagnosis. Within the tribe Scotobiini, Pumiliofossorum can be easily distinguished from other genera by the following combination of characters: antennae short, surpassing anterior margin of pronotum, capitate, antennomeres II–XI wider than long, the four last antennomeres bigger than the preceding ones; last antennomere truncated, slightly concave ( Figs. 6, 7 ); pronotum tranverse, oval shape, margins not carinate, lateral margin rounded, slopping down, posterior angles not defined ( Figs. 2 , 16 ); elytra acuminate, widest behind humeri ( Figs. 1 , 16 ); tibiae laterally compressed with outer margin expanded, convex and inner margin with long golden setae ( Figs. 8–13 ); protibiae flattened, markedly expanded outwards ( Figs. 8 , 18 ).

Description. Length 4.0–6.0 mm, width 2.5 –3.0 mm. Apterous. Body outline oval, base of elytra constricted. Color reddish brown to dark brown, shiny; antennae and legs reddish brown ( Figs. 1 , 19 ). Head. Labrum light brown, visible, with round punctures and golden setae, anterior margin bisinuate with thick short golden setae ( Fig. 4 ). Clypeus broad, width of anterior margin exceeding width of interocular distance, anterior margin concave ( Fig. 4 ). Clypeus and frons with strong and dense punctures, clypeal suture transverse, weakly depressed ( Figs. 4, 5 ). Head widest at epicanthus, before eyes. Epicanthus prominent, almost dividing the eyes into lower and upper portions ( Figs. 4, 5 ). Eyes narrow, sunken, groove-like in dorsal view, half-moon shaped in lateral view ( Figs. 4, 5 ). Antennae capitate, flattened dorsoventrally ( Figs. 5, 6 ), short, surpassing anterior margin of pronotum. Antennomeres progressively increasing in width, II–XI wider than long, antennomeres IX and XI of same width, antennomere X wider than antennomeres IX and XI ( Figs. 6 , 16 ); antennomeres VIII–X with dome-shaped placoid sensoriae on rims ( Fig. 6 ), antennomere XI apex truncate and slightly concave, dome-shaped placoid sensoriae on whole apical surface ( Fig. 7 ). Mentum small, longer than wide, subtrapezoidal, subgenal process remote from submentum and mentum ( Fig. 3 ). Thorax. Pronotum transverse, 1.5 x wider than long, oval shaped, slightly domed, widest before midpoint, with round punctures ( Fig. 2 ). Margins not carinate, anterior margin slightly bisinuate, anterior angles rounded, lateral margin rounded, slopping towards venter, posterior angles not defined. Anterior and posterior margin with short golden setae projected outward ( Figs. 2 , 4 ). Proepisternum not visible from above, with long golden setae ( Fig. 3 ). Hypomera, prosternum, mesosternum and metasternum with punctures less dense than pronotal punctures, clothed in long golden disperse setae. Intercoxal distances shorter than coxal diameters ( Figs. 3 , 15 ). Scutellum small, triangular, completely exposed ( Figs. 1 , 16 ). Elytral length equal to 1.5–2.0 x of the pronotal length, acuminate, widest behind humeri, narrowing towards posterior apex, 1.4 x longer than wide; with four or five longitudinal grooves on internal half, with wrinkles, punctures, and sparse golden setae in lateral area; humeri curved, prominent ( Figs. 1 , 16 ); suture flat; pseudopleuron with long golden setae; epipleuron not marked. Abdomen. Ventrites with punctures separated by twice their diameter and sparse golden setae of moderate length. Legs. Femora and tibiae with punctures separated by a distance twice or more the diameter of puncture, each puncture with a long, gold central seta. Tibiae laterally compressed, outer margin expanded, convex, inner margin with long golden setae ( Figs. 8–15 ). Protibiae median section flattened and expanded outwards, outer margin strongly convex, inner margin slightly concave ( Figs. 8, 9 , 18 ). Mesotibiae and metatibiae outer margins slightly convex, serrated, with row of contiguous spines, inner margin straight ( Figs. 10–13 ). Mesotibiae median section triangular. Metatibiae median section flattened. Last tarsomere twice as long as each of the preceding ones ( Figs. 8, 10, 12, 14 ). Spurs of the protibiae short, approximately as long as the first tarsomere (forespurs of Mathews et al. 2010: 582). Metafemoral-tibial articulation not reaching elytral apex ( Figs. 1 , 16 ).

Sexual dimorphism: Female with abdominal sterna slightly convex; male with central concavity from first to third visible abdominal ventrites, more pronounced on second ventrite.

Species included. Pumiliofossorum moche Silvestro & Flores, sp. nov., and P. sechurae Giraldo & Flores, sp. nov.

Distribution and habitat. Coastal desert of Northwestern Peru in sandy soils. Pumiliofossorum species fit the morphological features of the sand swimmers ( Matthews et al., 2010: 582): small size, shortened antenna, deeplyinserted eyes, body covered with long setae, and all tibiae bearing widened and flattened outer faces for digging and pushing.

Figures

FIGURES 1 – 3. Pumiliofossorum moche sp. nov. Habitus dorsal view (1), prothorax dorsal and ventral view (2, 3).

FIGURES 4 – 7. Pumiliofossorum moche sp. nov. Head dorsal and latero-dorsal view (4, 5), antenna dorsal (6) and last antennomere (7).

FIGURES 8 – 15. Pumiliofossorum moche sp. nov. Protibia, dorsal and ventral view (8, 9), mesotibia, dorsal and ventral view (10, 11), metatibia, dorsal and ventral view (12, 13), last tarsomere (14) and meso- and metacoxae (15).

FIGURES 16 – 19. Pumiliofossorum sechurae sp. nov. Habitus of allotype in dorsal (16), lateral (17), frontal (18) and ventral view (19).

FIGURES 20 – 21. Sechura desert, habitat of Pumiliofossorum sechurae sp. nov. Sand dune (20), and pitfall trap (21).