Pachycerina potentilla, Davies & Miller, 2009

Davies, Gregory B. P. & Miller, Raymond M., 2009, Revision of Afrotropical Pachycerina Macquart (Diptera: Lauxaniidae), African Invertebrates 50 (2), pp. 295-295 : 316

Pachycerina potentilla sp. n.

Figs 17 , 29 , 46

Etymology: From the Latin potens (powerful or strong), in reference to the intense black pigmentation of the body markings (vittae), which makes this a visually striking taxon, even when viewed with the naked eye.

Diagnosis: The pronounced intensity of the black body markings is distinctive contrasting starkly with the yellow body colour. The elongated black ocellar spot, infuscation of the outer (lateral) half of scape and pedicel, largely black abdomen and lack of medial spur on S5 are also notable. P. potentilla is endemic to the island of São Tomé, Gulf of Guinea, West Africa and is the only Pachycerina recorded from this island.

Description:

Head: Fronto-orbital plates dark brown to black, contrasting with yellow of postfrons. Ocellar spot black, noticeably elongated extending halfway down postfrons. Prefrontal spots large, black and touching prefrons laterally. Lateral side of pedicel and scape orange-brown (infuscated), inner side yellow. Postpedicel yellow.

Thorax: Patterning intensely coloured. Scutum with prominent, black acrostichal, dorsocentral and presutural vittae. Posteriorly, acrostichal and dorsocentral vittae coalesce. Upper lateral vitta running longitudinally from lower half of humeral callus posteriorly to postnotum. Lower lateral vitta running along dorsal margin of sternopleuron. Procoxa lightly infuscated, profemur lightly infuscated (but inner face yellow), protibia and protarsus heavily infuscated (black). Remaining legs all yellow, no infuscation, including tarsus (except darkened meso- and metapretarsus). Wing with anterior third of wing infuscated. Haltere pale yellow, distal knob weakly infuscated.

Abdomen: Brownish black, T6 predominantly yellow with large, paired black spots. Sternites yellow.

Male terminalia ( Figs 17 , 29 , 46 ): S5 with straight posterior processes and lacking a medial spur. Surstyli about equal in length to epandrium. Gonopods asymmetric, right gonopod with small lateral spinule (not shown in illustration). Left gonopod with small tuft of setulae laterally.

Measurements: ơ (n=2), ^(n=2): head length – ơ 0.7, ^0.7; thorax length (incl. scutellum) – ơ 2.0, ^1.9; abdomen – ơ not measured, ^1.6; wing length – ơ 3.7, ^3.8.

Holotype: ơ SÃO TOMÉ: Bom Successo [0°17'N: 6°38'E], 7–8.vi.1999, A. Polaszek ( NMWC).

Other material examined: SÃO TOMÉ: 3^same data as holotype ( NMWC); 2ơ 1^São Tomé [0°20'S: 06°40'E], 6.xi.1932, W.H. Tams ( BMNH) .

Comment: Simmonds (1969: 26) recorded P. seychellensis from Principé Island, Gulf of Guinea. The whereabouts of this material is not known to us, but on distributional grounds this identification is highly questionable, and it is likely that Simmonds had collected specimens of P. potentilla or a new, undescribed species. Simmonds’ putative record is the source of the entry ‘?Principe’ in the Afrotropical Catalogue (Miller 1980).

Figures

Figs 17–22. Posterior view of male terminalia: (17) Pachycerina potentilla sp. n.; (18) Pachycerina pellocera sp. n.; (19) Pachycerina atrimela sp. n.; (20) Pachycerina obscuripennis Lamb; (21) Pachycerina seychellensis Lamb; (22) Pachycerina nigrivittata sp. n.Abbreviations: pro – protandrium, epa – epandrium, sur – surstylus. Scale bar = 0.8 mm.

Figs 28–33. Dorsal view of male inner genitalia: (28) Pachycerina obscuripennis Lamb; (29) Pachycerina potentilla sp. n.; (30) Pachycerina stuckenbergi sp. n.; (31) Pachycerina atrimela sp. n.; (32) Pachycerina gabela sp. n.; (33) Pachycerina pellocera sp. n. Abbreviation: aed apo – aedeagal apodeme. Scale bar = 0.5 mm.

Figs 39–48. Sternite 5 of male Pachycerina species: (39) P. vaga Adams; (40) P. nigrivittata sp. n.; (41) P. gabela sp. n.; (42) P. atrimela sp. n.; (43) P. pellocera sp. n.; (44) P. stuckenbergi sp. n.; (45) P. crinicornis (Thomson); (46) P. potentilla sp. n.; (47) P.seychellensis Lamb; (48) P. micropunctata sp. n. Abbreviation: post proc – posterior process. Scale bar = 0.5 mm.