Stigmus cuculus Dudgeon

Pulawski, Wojciech J. & Gracy, Ramasamy Gandhi, 2018, Redescription of Two Indian Stigmina (Hymenoptera: Crabronidae), Proceedings of the California Academy of Sciences 64 (10), pp. 333-340 : 333-334

Stigmus cuculus Dudgeon

Stigmus cuculus Dudgeon in Nurse, 1903:12, ♀. Syntypes: ♀, India: Himachal Pradesh: Kangra Valley: Holta in Palampur ( BMNH), one syntype examined. – Ramakrishna Aiyar, 1916:556 (in catalog of Indian aculeates described after Bingham, 1897); Tsuneki, 1954:5 (in key to Eurasian Stigmus ), 29 (in revision of Eurasian Stigmus ); R. Bohart and Menke, 1976:189 (in checklist of world Sphecidae ).

This species was described in one brief sentence: “Differs from S. congruus (Walk.) in being less than half the size, in the whole of the antennae being testaceous, clypeus subtriangular and slightly produced; tubercles not white.” The reference to S. congruus , now placed in Carinostigmus , suggests that S. cuculus is also a Carinostigmus . In fact, the species is a Stigmus , as indicated by the hindwing submedian cell not reduced and the crossvein cu-a positioned next to the origin of media ( Finnamore, 1995). In addition, the midfrontal carina and the paraorbital groove are lacking, and the gastral petiole is longitudinally carinate. Also, the interantennal tubercle is absent, the mesopleuron is mostly unsculptured, shiny (as opposed to the coarsely sculptured mesopleuron of Aykhustigmus ), and the hindwing vein cu-a originates at some distance from apex of submedial cell.

As far as we know, no specimens of this species have been collected since its description.

RECOGNITION.— Of the 24 described species of Stigmus other than S. cuculus , we could examine 12, and we have also seen a number of undescribed species. It appears that S. cuculus has a unique combination of the nonemarginate free margin of the clypeal lobe and of the paraorbital sulcus on the frons, whereas the black pronotal lobe is a subsidiary recognition feature. Also, the area between the scrobal sulcus and the hypersternaulus is aciculate, almost unsculptured. An undescribed species from Thailand is similar, but differs in having the mesopleuron conspicuously ridged and rugose above the hypersternaulus, and the anterolateral corner of the clypeal lobe more prominent than in S. cuculus .

REDESCRIPTION.— ♀. Inner eye margins slightly converging below ( Fig. 1 ). Head subquadrate in dorsal view, lateral margins relatively slightly converging behind eyes ( Fig. 3 ). Gena in profile narrower than eye ( Fig. 4 ). Middle clypeal lobe truncate apically ( Fig. 2 ), not subtriangular as stated in original description. Free margin of labrum truncate. Frons aciculate up to the level of scape length, unsculptured above, with smooth sulcus adjacent to inner eye orbit and extending to upper level of aciculate area; upper frons without longitudinal impression (that is present in S. pendulus Panzer ). Ocellocular distance 2.0 × as long as interocellar distance. Prothorax side striate. Area between scrobal sulcus and hypersternaulus aciculate, almost unsculptured; area above scrobal sulcus dull, minutely, irregularly ridged longitudinally. Scutum aciculate, with scattered punctures ( Fig. 5 ). Propodeum markedly reticulate ( Fig. 6 ). Hindwing median vein emerging from apex of anal cell (it emerges a short distance from apex of anal cell in S. convergens Tsuneki , S. japonicus Tsuneki , and S. quadriceps Tsuneki , see Budrys, 1987). Gastral petiole with a pair of longitudinal carinae, finely ridged longitudinally on each side of carinae; petiole length in dorsal view equal to hindtarsomeres I and II combined.

Head, thorax, propodeum, and gaster all black (including pronotal lobe), but mandible yellow (except apically) and antenna largely testaceous. Foretrochanter testaceous, mid- and hindtrochanter testaceous anteriorly, black posteriorly; femora black; tibiae and tarsi testaceous.

♂.— Unknown.

RECORDS ( Fig. 7 ).— Known only from the type locality.

Figures

FIGURES 1–2. Stigmus cuculus Dudgeon, syntype female. (1) Head in frontal view; (2) Clypeus and adjacent frons.

FIGURES 3–6. Stigmus cuculus Dudgeon, syntype female. (3) Head in dorsal view; (4) Head in lateral view; (5) Scutum in dorsal view; (6) Propodeal dorsum.

FIGURE 7. Map of Indian subcontinent with collecting localities of Stigmus cuculus Dudgeon (square) and Carinostigmus aterrimus (R. Turner) (circles).