Physotarsus Townes 1966
Creators: name: Zhaurova, Kira
name: Wharton, Robert
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Physotarsus

description: Physotarsus Townes, 1966
Physotarsus Townes, 1966: 139, 330 (catalog, original description); Townes & Townes 1966: 139 (catalog; new combinations); Townes 1970b: 102 –104 (key to genera of Scolobatini, copy of original description); Carlson 1979: 592 (catalog); Gauld 1997: 181 –184 (revision of Physotarsus of Costa Rica; detailed redescription of genus, illustrated descriptions of 6 new species from Costa Rica); Yu and Horstmann 1997: 455 (catalog).
Type species: Tryphon maculipennis Cresson, 1874, by original designation.
Diagnosis. Ventral margin of clypeus thickened medially but never with sharply pointed median tooth. Occipital carina absent mid-dorsally, present at least ventrally. First flagellomere with tyloid laterally bearing 15 or fewer sensilla. Fore wing areolet always absent. Hind tarsi swollen, at least in male.
Physotarsus lacks the sharply pointed median tooth on the clypeus that characterizes Scolobates Gravenhorst and Onarion Townes (Figs 5–8), and is therefore most similar to Catucaba Graf, Kumagai and Dutra. The apical margin of the clypeus is variously thickened in Physotarsus and uniformly thin and sharp in Catucaba.
Description. Length: body 3.2–9.7 mm, fore wing 3.0– 10.4 mm. Clypeus 2.4–4.0X as wide as long; in profile, varying from weakly, evenly convex to flattened medially and somewhat tuberculate laterally, sometimes separated medially by a weak transverse ridge; separated from face dorsomedially by epistomal sulcus that varies from distinctly impressed to barely visible; ventral margin variously thickened, but without sharply pointed median tooth. Anterior tentorial pits oval to slightly elongate with lateromost corners pointed laterad or upcurved. Malar space 0.2–0.8X basal width of mandible; mandible with lower tooth slightly longer than upper; mandible tapering over basal 0.3–0.5, almost parallel-sided apically. Dorsal margin of mandible without distinct median convexity. Mouthparts simple to weakly haustellate, labiomaxillary complex never as elongate as in Onarion. Face smooth to deeply and relatively densely punctate, 1.2–2.3X as wide as long, with small median tooth or tubercle dorsally. Interantennal area flat to slightly concave, anterior margin of torulus situated at about 0.6–0.8 of eye height. Widest diameter of torulus 1.0–1.6X widest diameter of median ocellus. Area between lateral ocelli flat to strongly depressed, distance between lateral ocelli 0.4–1.5X their widest diameter, distance from lateral ocellus to eye margin 1.4–2.8X widest diameter of lateral ocellus. Area behind ocelli regularly rounded to sharply declivitous. Antennae with 22–47 flagellomeres, longer to much longer than length of body. First flagellomere with small tyloid laterally, with 15 or fewer sensilla per tyloid; flagellomere length 0.7–1.6X widest transverse diameter of eye, second flagellomere 0.4–0.8X length of first. Occipital carina incomplete, narrowly to broadly effaced dorsally, present on ventral 0.2–0.8 of head, rarely joining hypostomal carina at or before mandibular base, the two carinae often widely separated at mandibular base ventrally but narrowly separated, nearly joining in some species. Pronotum dorsally with distinctly impressed transverse groove, anterior margin truncate to quite strongly emarginate, narrow to exceptionally narrow dorsomedially. Lateral groove of pronotum highly variable, from absent to complete; epomia absent. Pronotum glabrous to variably punctate, sometimes partially rugose. Mesoscutum glabrous to densely punctate, notauli absent. Epicnemial carina extending along ventral 0.2–0.4 of posterior margin of pronotum, sometimes turned towards but only rarely reaching thickened anterior margin of mesopleuron.
Mesopleuron always lightly pubescent ventrally, smooth to densely punctate laterally. Propodeum with pleural carina varying from absent to complete, median longitudinal carinae usually absent, sometimes present as posterior vestiges; punctation variable, usually absent posteromedially, sometimes present anteromedially; punctation always denser laterally than medially. Hind trochanter less than 3.0X as long as basally wide, apical margin of trochanter reaching apical margin of trochantellus. Pretarsus longer than tarsomere 4. Pectination of tarsal claws varying from presence of stout setae only at extreme base to fully or almost fully pectinate. Fore wing without areolet (3rs-m always absent); stigma variable in shape from quite narrow to broadly hemispherical, Rs+2r arising from or more usually distinctly basad midpoint of stigma; marginal cell about 2.5–3.3X as long as wide; 2m-cu with a single bulla; Cu1a about 0.3–1.0X length of 2cu- a. Hind wing with junction of M and rs-m relatively basal; 1st abscissa of Cu1 subequal to distinctly longer than cu-a, the relative lengths often quite variable within species; distal abscissa of 1A usually entirely absent, more rarely present as distinct basal stub (as in the type species). Metasomal T1 about 1.2–2.4X longer than width at apex; flattened to weakly concave anteriorly, usually weakly convex posteriorly; basal depression very shallow to moderately deep at attachment of dorsal tendon, the depression often not delimited posteriorly; dorsomedian longitudinal carinae absent; dorsolateral longitudinal carinae usually present basally, sometimes as a distinct flange over glymma, absent posteriorad spiracle; T1 spiracles sometimes slightly protruding in profile. Glymma present as narrow groove at extreme base, widening somewhat posteriorly ventrad dorsal tendon attachment, not distinctly delimited posteriorly. S1 short to very short, posterior margin extending 0.1–0.4X length of T1. Cerci small, usually sessile or nearly so, never protruding greater than basal width, sparsely setose. Ovipositor short, with deep, broad, subapical notch; sheath usually broader apically than at base, usually sparsely long-setose apically, pattern slightly variable. Color extremely variable; wings largely hyaline, though variously yellow to fuscous in some species; often with dark apical spot.
Distribution. Restricted to the New World, occurring from southern Canada to northwestern Argentina and southeastern Brazil. In addition to the North American specimens listed below from Arizona, California, Nebraska, Nevada, New Mexico, and Texas, we have seen several additional specimens from southern U. S. (AEIC, CNC, USNM), including three from Oklahoma and one from North Carolina. We also examined one specimen from Saskatchewan, Canada (CNC), a record that needs verification.
Biology. Gauld (1997) provided seasonal and habitat data for the six species he described from Costa Rica. There is only one host record: several specimens of P. adriani were reared from cocoons of the argid sawfly Trochophora lobata in Costa Rica (Gauld 1997; Janzen 2006).
Remarks. The shape of the clypeus is quite variable across its width, with the margin generally thickened medially, thinner and sometimes reflected laterally. The greatest degree of interspecific variation is in the median part of the clypeal margin, with the following states observed: margin evenly convex, weakly and evenly thickened (Fig. 5); margin irregularly thickened, with a distinct, broadly rounded or truncate median lobe (Fig. 6); margin with a narrower, median tooth (Fig. 7) similar to, but not as pointed as, that in the species of Scolobates (Fig. 8) and Onarion. These states are difficult to describe accurately because they largely represent a continuum of forms across the genus. The shape of the male subgenital plate, as first noted by Gauld (1997), and aedeagus proved useful in discriminating among species that were otherwise similar in appearance. Unfortunately, these features were not always visible and males were unavailable for several species. The name Physotarsus is derived from Greek and refers to the inflated hind tarsus of males (Townes 1966), a feature which is also found in other Scolobatini from the New World.
It is apparent from the material available that Physotarsus is widely distributed, morphologically diverse, and speciose. During the course of this study, 22 additional morphospecies, each represented by a single specimen, were examined. Phylogenetic analysis is deemed premature due to the inability to score characters, especially for males, for many of the taxa. Lack of males is particularly problematic as our study reveals considerable morphological diversity in male genitalia. Our preliminary attempts to analyze relationships resulted in poorly resolved trees which changed dramatically when additional taxa were added. To facilitate future work, we offer the following observations. The species treated here fall into three groups, with two taxa difficult to place. We propose these as strictly informal species groups in the absence of any specific analysis of their monophyly. The first group is represented by very large, smooth-bodied species with fuscous wings and pectinate tarsal claws and includes P. maculipennis and P. varicornis (Cameron). Physotarsus melipennis Zhaurova n. sp. also has fuscous wings, but is more distinctly punctate and lacks pectinate tarsal claws. It does not fall readily into any of the three groups recognized here. A second group consists of similarly smooth-bodied species all of which have the dorsal tendon attaching within a shallow to moderately deep pit that is discrete and more or less steep-sided distally. All species have the head and mesosoma in various pastel colors and also have fore wings with an apically infumate spot, though this is hard to discern in P. albus Zhaurova n. sp., in which the entire wing is weakly infumate. Species included in this second group are P. adriani Gauld, P. albus Zhaurova n. sp., P. bonillae Gauld, P. glabellus Zhaurova n. sp., P. j a m e s i Zhaurova n. sp., P. leucohypopygus Zhaurova n. sp., P. oculatus Zhaurova n. sp., and P. niveus Zhaurova n. sp. These species are distributed from southern Brazil to Costa Rica and the Lesser Antilles. Physotarsus claviger Zhaurova n. sp., from Argentina, is similar but has extensive dark markings on the head and mesosoma. Physotarsus castilloi Gauld and P. eliethi Gauld, both from Costa Rica, also probably belong here though the nature of the dorsal tendon attachment was not examined. Physotarsus luteus is similarly smoothbodied and resembles several of the smaller species in this second group but the dorsal tendon attachment does not appear to be the same. All remaining species are characterized by distinctly punctate face and mesopleuron, with some species also distinctly punctate on the mesoscutum. The hind femur and tibia are largely to entirely orange in these species. The described species in this third group are distributed from Durango and Nuevo Leon, Mexico to Nebraska and Nevada, USA.
description: Published as part of Zhaurova, Kira & Wharton, Robert, 2009, A revision of Physotarsus Townes (Hymenoptera: Ichneumonidae: Ctenopelmatinae), with description of 18 new species, pp. 1-52 in Zootaxa 2207 on pages 7-8, DOI: 10.5281/zenodo.189753