Piasites Seyrig, 1952

Bordera, Santiago & Santos, Bernardo F., 2022, A review of Piasites Seyrig (Hymenoptera, Ichneumonidae, Cryptinae), with description of seven new species, Journal of Hymenoptera Research 90, pp. 23-57 : 23

publication ID	https://dx.doi.org/10.3897/jhr.90.81095
publication LSID	lsid:zoobank.org:pub:EA0491B0-3B62-4360-B9F7-9A24E3693248
persistent identifier	https://treatment.plazi.org/id/BA8B0355-19E5-5AA7-9ACC-F8778F31DAAE
treatment provided by	Journal of Hymenoptera Research by Pensoft
scientific name	Piasites Seyrig, 1952
status

Treatment

Piasites Seyrig, 1952 View in CoL View at ENA

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11 , 12 View Figure 12 , 13 View Figure 13 , 14 View Figure 14 , 15 View Figure 15

Piasites Seyrig, 1952: 191. Type species: Piasites carinatus Seyrig, by original designation.

Diagnosis.

Frons smooth and shiny, without horns or carinae; occipital carina joining hypostomal carina close to or at base of mandible; posterior margin of metanotum without teeth-like projections; transverse furrow at base of propodeum with distinct longitudinal striae; areolet small to medium-sized, open (crossvein 3rs-m absent); T1 with distinct anterolateral tooth.

Description.

Female. Fore wing 4.0-8.1 mm long. Body moderately slender, shiny and variously sculptured.

Head. Frons and vertex smooth and shiny, frons with a median vertical line. Occiput sharply inclined; posterior surface of head almost vertical, somewhat concave, starting almost immediately posteriorly to lateral ocelli. Occipital carina sharp, complete dorsally except in P. quasimodus , meeting hypostomal carina close to or at base of mandible. Temple and gena in lateral view moderately wide, ventrally distinctly wider than on dorsal 0.2. Clypeus 1.6-1.9 × as broad as medially long, dorsally distinctly convex, ventral margin slightly rounded or somewhat truncate, medially with or without a weak denticle. Labrum conspicuously exposed with long setae on apical margin. Antenna with 23-32 flagellomeres; subapical flagellomeres gradually thicker than basal ones, flattened ventrally. Tip of apical flagellomere rounded, without distinct cluster of modified setae. Malar space moderately long, 0.5-0.8 × as long as basal mandibular width, granulate. Mandible moderately short, 1.35-1.65 × as long as basal width, dorsal tooth slightly to distinctly longer than ventral one.

Mesosoma. Pronotum variously sculptured but always with distinct longitudinal striae; dorsal margin sometimes slightly swollen near dorsal end of epomia; epomia short but strong except in some specimens of P. carinatus . Mesoscutum subcircular to ovoid, 1.05-1.25 × as long as wide; notaulus reaching past half of mesoscutum length, variously impressed. Epicnemial carina reaching at least 0.5 of distance to subtegular ridge. Sternaulus deep, reaching posterior rim of mesopleuron. Posterior transverse carina of mesosternum represented by a short median ridge, approximately v-shaped. Posterior margin of metanotum without distinct teeth-like projections. Transverse furrow at base of propodeum moderately wide and deep, with distinct longitudinal striae. Pleural carina distinct. Submetaplural carina forming a conspicuous, blunt, subtriangular elevation joining juxtacoxal carina. Fore tibia slightly swollen. Fourth tarsomeres distinctly bilobed, lateral lobes much longer than mesal ones. Propodeum moderately small and more or less evenly rounded in lateral view, in dorsal view about as long as wide; anterior margin medially concave; spiracle circular or elliptic. Longitudinal carinae of propodeum absent, except pleural carina. Anterior transverse carina complete and strong but sometimes almost obscured by strong propodeal sculpture. Posterior transverse carina usually complete, except interrupted medially in P. perinetensis and P. orbitalis . Wings hyaline; ramulus absent; cross-vein 1cu-a arising opposite M&RS or basad by up to 0.3 × of its length; second absissa of vein CU slightly shorter than cross-vein 2cu-a; cross-vein 2m-cu inclivous and usually slightly curved, its bulla moderately short, occupying less than 0.3 × of its length; areolet small to medium sized (in most species 0.45-0.90 × as long as abscissa of vein 2m-cu above bulla, up to 1.7 × in P. quasimodus ); cross-vein 3rs-m absent. Hind wing vein M+CU apically strongly arched; vein cu-a distinctly shorter than first absissa of vein CU; second absissa of CU distinct but not reaching wing margin, its apical 0.5 approximately straight; second abscissa of AA ( Townes’ “brachiella”) distinct, except in some specimens of P. quasimodus .

Metasoma. T1 moderately short, 2.00-2.85 × as long as posteriorly broad; petiole in cross-section approximately cylindric, with weak anterolateral tooth; median dorsal and ventro-lateral carinae absent; dorso-lateral carina at least partially distinct. Posterior apex of sternite I opposite spiracle. Thyridium wider than long. T7-8 as long as T5-6. Ovipositor sheath 0.4-0.7 × as long as hind tibia (in most species 0.5-0.6 ×); ovipositor straight, compressed, apex moderately pointed, with distinct nodus and notch; dorsal valve without ridges or teeth; ventral valve with numerous oblique ridges or teeth (10-12), not expanded as a lobe.

Male. Generally similar to respective females. Morphological secondary sexual differences are usually more or less uniform within Cryptini and apply to males of Piasites as follows. General body size usually smaller than in female. Antenna with 24-31 flagellomeres, from f13(17) to apex flattened ventrally, each flagellomere shorter than in female; white band of flagellum starting more apically. Transverse furrow at base of propodeum medially longer and shallower than in female. Propodeum with sculpture distinctly coarser than in female. Fore tibia not swollen. T1 slenderer and less widened posteriorly than in female.

Remarks.

The examination of multiple specimens of P. carinatus as well as of additional species of Piasites resulted in a redefinition that is at odds with some of the characters described by Townes (1970) for the genus. For instance, Townes stated that Piasites has the epomia "indistinct or absent", but the epomia is distinct and strong in most of the new species, and even specimens of P. carinatus often have a distinct epomia (Fig. 4 View Figure 4 ), though it is sometimes obscured by the pronotum sculpture. Townes also noted in the key to the genera of Ceratocryptina (couplet 14) that in Piasites the notaulus is "not sharp", though most species of the genus have a distinct and deeply impressed notaulus. Another potential problem in determining the genus from Townes’ key arises at couplet 6, in which the state "brachiella vein present, reaching at least half the distance to wing margin" leads to the portion of the key containing Piasites . However, some specimens of P. quasimodus have the hind wing vein 2-1A ( “brachiella”) very short or indistinct, which would lead users to the wrong couplet.

Compared to other cryptine genera, Piasites is most similar to closely related taxa in the Ischnus clade; in particular, species of Piasites can be mistaken for Bozakites , a large Afrotropical genus that occurs both in continental Africa and in Madagascar. Piasites can be separated from Bozakites by the lack of a tooth-like widening on posterior margin of the metanotum (present in Bozakites , just laterad of each side of postscutellum); frons smooth and shiny (vs. granulate, matte and often with weak punctures); occipital carina joining hypostomal carina close to or at base of mandible (vs. joining hypostomal carina far from mandible base); and anterior margin of pronotum not bordered posteriorly by a carina (vs. bordered by a strong carina). The two genera also appear as reciprocally monophyletic in the analyses of Santos (2017), further reinforcing that they represent distinct taxonomic entities. It should be noted, however, that Bozakites is a large and variable genus; further phylogenetic analyses including more species of both genera are needed in order to discard the possibility that Piasites is nested within Bozakites .

While herein we increase the number of known Piasites species from one to eight, the genus certainly includes further species. The undescribed species included in the analyses of Santos (2017) does not closely match any of the species treated here, but it was not described in this work because it is represented by a single specimen that was damaged for DNA extraction. Close examination of the extensive Malagasy material collected in multiple expeditions by the California Academy of Sciences ( Fisher 2005) may reveal multiple additional species, but we chose to present the information that is readily available in order to advance the knowledge of the Malagasy fauna.

Biology.

Unknown.

Distribution.

Endemic to Madagascar. Extensive material from continental Africa was examined, and no specimens corresponding to the taxonomic delimitation of Piasites were found.