Gyrasida Koch, 1962

Flores, Gustavo E. & Vidal, Pedro, 2009, Systematic position and cladistic analysis of Gyrasida Koch, a remarkable genus of Praocini (Coleoptera: Tenebrionidae) from Chile, Zootaxa 1978, pp. 48-62 : 52-56

Gyrasida Koch

Gyrasida Koch 1962: 127 (as a subgenus of Afrasida ); Vidal & Flores 2007: 409. Type species: Afrasida propensa Wilke 1921 , by monotypy. Holotype of G. propensa in MNHUB.

Species included. Gyrasida includes six species: G. propensa (Wilke) (type species), plus five species described by Vidal & Flores (2007): G. lucianoi Flores & Vidal , G. fernandoi Flores & Vidal , G. tomasi Vidal , G. franciscae Vidal , and G. camilae Vidal. Key to species in Vidal & Flores 2007: 415.

Diagnosis. Recognized among other Praocini by the following combination of characters: profemora with a conspicuous, smooth, glabrous, and shiny longitudinal ridge on proximal half of anterior surface; anterior area of clypeus inclined downwards forming an angle; clypeal suture as horizontal groove, clypeus lower than frons; frons with two transverse carinae forming an inverted "V", covering dorsally the clypeal suture; maxillary palpi with last segment subcylindrical; antennomere 11 longer than 10; pronotum widest at the midpoint; central area of anterior margin of pronotum notched and broadened; elytron with a main paramedian carina; anterior quarter of epipleuron twice as wide as posterior half; sexual dimorphism: female with a central nippleshaped process on central area of metasternum, male lacking central process on central area of metasternum.

Redescription. Length 7.5−15.0 mm; habitus oval, flattened or convex; body dark brown to black with antennae and legs dark brown to black.

Head. Hypognathous. Epipharynx with anterior margin dorsally exposed. Labrum with large punctures and setae, widest at the midpoint. Clypeus notched anteriorly, with deep and irregular punctures, with setae, and two lateral depressions; anterior area of clypeal surface inclined downwards forming an angle; clypeal suture wide, as horizontal groove divided centrally by a longitudinal depression going up towards frons; clypeus lower than frons. Frons pubescent, with two transverse carinae forming an inverted "V", covering dorsally the clypeal suture, with a longitudinal groove, and with two protuberances medial to eyes. Ligula sclerotized and ventrally exposed, exceeding half mentum area, subequal in width and size to mentum ( Fig. 10); labial palps inserted at middle of ventral surface of ligula; base of mandible two times higher in respect to apex; maxillary palpi with last segment subcylindrical ( Fig. 10). Eyes oval, not depressed by frontal proyection. Antennae short, reaching 1/3 to 1/2 of lateral margin of pronotal length; length of antennomere 11 longer than 10; antennomeres 9 and 10 with a unique semicircular terminal tomentose sensory patch.

Thorax. Pronotum with two kinds of setae, one stout, arising in spinae, dark brown, and other finer arising from slightly raised protuberances, golden or light brown; with large, irregular punctures and protuberances; anterior angles rounded; anterior margin with central area notched, broadened, lacking edge, without groove between anterior margin and disc, width of anterior margin not exceeding the width of posterior margin; lateral margin concave ( Fig. 1), remote from disc, widest at the midpoint, with frequent stout setae and very few finer ones; posterior margin bisinuate, with a slightly marked median notch, of similar width to base of elytra, joined in central half to elytra; disc convex, with a longitudinal central groove wider in central area, with two smaller lateral depressions, with two or four large protuberances, and many small, irregular protuberances, sometimes confluent. Prosternum horizontal to discretely convex, with distinctive anterior margin projected anteriorly covering mouthparts ventrally. Proepisternum with setae and protuberances, without grooves. Prosternal apophysis subrectangular or rounded, expanded or not distally. Mesosternum inclined forward, separated from prosternum. Meso- and metepisternum with punctures, with rugose striae.

Elytron with dorsal surface arched, pubescent, without punctures, with many irregular protuberances, sometimes sharp or spine like; with a main carina paramedian, raised, with or without secondary lateral carina; suture slightly raised or not; posterior third with two protuberances continuous with main carina; dorsal surface with symmetrical rows of wrinkles and protuberances irregularly arranged pointing downwards between suture and main carina; lateral margin simple and sinuate; pseudopleuron with protuberances and setae, some of which arising from protuberances, without punctures; epipleuron conspicuous or not, with setae and protuberances, similar to pseudopleuron in texture, wider anteriorly, anterior quarter twice as wide as posterior half, anterior margin not reaching elytral humeri nor posterior pronotal angle, texture similar to that of elytron, and with a slight posterior longitudinal groove over its medial side related to ventrites 6 and 7.

Venter. Distance between meso- and metacoxae exceeding half of metacoxal length ( Fig. 12). Abdominal sterna with many setae and some spines and protuberances irregularly distributed.

Legs. Densely covered by setae, many of them arising from sharp spines. Profemora with a conspicuous, smooth, glabrous, and shiny longitudinal ridge on proximal half of anterior surface. Tibiae with multiple spines, external process of distal margin of protibiae of equal length of protarsomere 1 + 2 combined.

Sexual dimorphism. Female with a nipple-shaped process on central area of metasternum, glabrous, shiny, pink to dark brown ( Vidal & Flores 2007: Fig. 2), male lacking central process on central area of metasternum.

Internal skeletal anatomy. Tentorium with medial straight bridge. Proendosternite joined to posterior part of procoxal cavities, with posterior arms short, directed posterad and broadened in posterior margin. Mesendosternite with horizontal arms short, with long, slender dorsal arms three times as long as horizontal arms, extended about half distance to tergum. Metendosternite ( Vidal & Flores 2007: Fig. 3) with arms long, fused with mesocoxal inflexions, extending beyond mesocoxal inflections about one third distance to tergum; width of stem equal to metacoxal width, length of stem exceeding width, and stem wider in upper than basal part. Elytralabdominal fusion accomplished by a ridge in the elytral epipleuron, which joins by a simple coaptation without interlocking with the abdominal sterna ( Doyen 1994: Fig. 205).

Male genitalia ( Figs. 13−16). Dorsal membrane of proctiger concave, with two sclerotized areas. Basal lamina of tegmen long (B/E> 1.0). Lateral styles of tegmen distally separated, widest at base, with setae on lateral margin and ventral surface. Median lobe moderate (0.75 <L/T ≤ 1.00), sheath-shaped, with apex rounded, not sclerotized ventrally, half the width in respect to tegmen, of equal width throughout.

Female genitalia ( Fig. 17). Spiculum with arms “V”-shaped. Coxites with short setae, basal lobe not extended over paraproct, baculi inclined 45°, midventral sclerite distally broadened. Paraprocts long (2.0 <P/C ≤ 3.0), glabrous. Proctiger with apicodorsal lobe extending length of coxite and with dorsal baculus extending proximad much beyond paraproct baculus. Vagina saccate. Spermathecal accesory gland two times length of vagina, with duct annulate and thick. Spermatheca with three tubes or less, shorter than vagina, all similar in width and branching pattern. Substantial variation in female genitalia was not found between the species of Gyrasida .

Geographic distribution. The species of Gyrasida occur in central Chile, in regions IV, V, VI, VII, VIII, and Metropolitan, from parallel 32º South to parallel 38º South ( Fig. 18) .

Habitat. The distribution range of the genus is from sea level to an altitude of 2000 meters. Its species occur in plain and mountain arid and semiarid environments of entomofaunal regions Coquimban Desert, Central Valley, Central Coastal Cordillera, and Northern Valdivian Forest ( Peña 1966).

Biology. Members of this genus live in leaf litter, under small logs and branches, always covered by the shadow of trees, usually well away from the sunlight. They are not found where the forest has been destroyed. Adults are nocturnal, and feed on plant debris. Copulating specimens have been observed to spend several hours coupled. Females lay their eggs by burying them in moist soil.