Trypoxylon basirufum, Muniz & Melo, 2021

Muniz, David Barros & Melo, Gabriel A. R., 2021, A new species of the wasp genus Trypoxylon from southern Brazil, with notes on the systematics of Pisoxylon (Hymenoptera, Crabronidae), Papéis Avulsos de Zoologia (Pap. Avulsos Zool., S. Paulo) 61, pp. 1-7 : 2

Scope of Pisoxylon and its status

in relation to Trypoxylon

Considering the three species of Pisoxylon recognized by Antropov (1998) in his revision, P. amenkei and P. xanthosoma are very close to each other morphologically, having many features in common. They differ from one another only by the length of the undivided part of the medial carina, the distance between the lateral ocellus and the corresponding inner eye margin, the thickness of the striations on the dorsal part of the propodeum and coloring of clypeal disc, the mesosoma, the metasoma and the silvery pubescence present in P. amenkei against the golden pubescence in P.xanthosoma .

On the other hand, P.roosevelti differs from these two species in many aspects: metapleura dorsally with a dilated lamellar margin; a small incision in the inner margin of the mandible; medial lobe of clypeus nearly straight in frontal view, with short rectangular protrusion in females; supraclypeal area somewhat longer than wide; lower part of frons with short,entire medial carina; dorsal part of propodeum with fine punctation and short transverse striae along medial groove; lateral part of propodeum without punctation and pilosity; males with antennae modified, at least with the F4 and F8 somewhat thickened and excised beneath; entire mesosoma black.

Pisoxylon roosevelti is very similar structurally to the new species described in the present work, T. basirufum sp. nov. Many of the characters shared between P.roosevelti and T. basirufum sp. nov. are common to several Trypoxylon s. str., like the dilated lamellar margin on the metapleura. This is one of the diagnostic characteristics of the fabricator group in Trypoxylon s. str. In this group there are also species that have a compact abdomen combined with the absence of a propodeal lateral carina, for example, T. pachygaster Richards, 1934 . Also, in our phylogenetic study of Trypoxylon sensu lato (Muniz and Melo, unpubl. data), we have found out that DNAsequence data from T. basirufum sp. nov. group it with other species of Trypoxylon s. str. and not with Pisoxylon amenkei as expected on morphological ground. Based on this,we propose transferring P.roosevelti to Trypoxylon s. str., keeping only P. amenkei and P. xanthosoma in the genus Pisoxylon .

Based on the above propositions, we reformulate the diagnosis of Pisoxylon to the following characters: inner eye orbits deeply notched; antennal sockets not contiguous with frontoclypeal suture; supraclypeal area shorter than wide; mandibles simple, having neither ventral incision (or tooth), nor inner tooth; male F6-F8 with tyloids; occipital carina incomplete and connected to the hypostomal carina in males and females; metapleura dorsally without dilated protrusion; propodeum moderately elongate-oval, without specific preapical structures; dorsal field of propodeum not clearly outlined, with medial groove; lateral carinae of propodeum absent; female hind coxa with minute subapical tubercle ventrally; hind wing with single basal hook and 2 groups of 5(6) + 3hamuli, separated from each other by a distance about twice the length of the proximal group of hamuli; intercalary hooks absent; metasoma sessile, relatively short, with non-elongate segment I. This reformulated diagnosis is based also on the undescribed male of Pisoxylon amenkei , obtained from trap nests in Paraná, Brazil (Muniz & Melo, unpubl. data).