Lateral ocelli separated by 1.1-1.2X their widest diameter from each other and about 1.8-2.0X their widest diameter from
eye margin. Antennae with 33-42 flagellomeres.
pronotum completely glabrous. mesoscutum (
1,
2) shiny, very sparsely punctate on anterior 0.3. T1 about twice as long as broad.
head yellow with broad, black median stripe extending from base of
antenna through
vertex;
occiput almost completely black.
mesosoma black and yellow (Fig. 4). T1 yellow basally with two black bands extending from
spiracle to or nearly to apex;
t2 and often
t3 with yellow triangular
patch medially (Fig. 8), otherwise dark brown to black, remaining tergites largely dark laterally, variously yellow to orange medially.
hind femur and
tibia orange, tarsomeres 1 and 2 brown, tarsomeres 3 and 4 usually yellow, sometimes only ventrally.
fore wing entirely hyaline.
Physotarsus concavus is one of several species with a black and yellow
mesosoma, a distinctly punctate mesopleuron (
1,
2), and a sparsely to impunctate mesoscutum (
1,
2). It is nearly identical to
P. cordatus,
P. emarginatus, and
P. truncatus_, but differs from these in the possession of distinctly pale middle tarsomeres on the hind leg. The subapical ring on the 0000343">flagellum is also more distinct in
P. concavus.
Physotarsus concavus is very similar in color to
P. emarginatus, and to a lesser extent
P. cordatus. The hind tarsi are darker in
P. emarginatus and the dorsoposterior
corner of the mesopleuron (
1,
2) is black, while in
P. cordatus the hind legs and
metasoma are more extensively orange.
Physotarsus concavus differs from both of these species in the more shallowly concave male
subgenital plate (Fig. 9).
