Pelecorhynchus biguttatus ( Philippi, 1865 )

Llanos, Lorena, Gonzalez, Christian R. & Córdoba, Mónica Saldarriaga, 2015, Revision of the New World species of the genus Pelecorhynchus Macquart, 1850 (Diptera: Pelecorhynchidae), Zootaxa 3955 (2), pp. 188-210 : 190-192

Pelecorhynchus biguttatus ( Philippi, 1865)

( Figs. 1–6 ).

Coenura biguttata Philippi, 1865: 726 . Type locality: Chile, Valdivia. Type: ♀, fragments in Museo Nacional de Historia Natural, Santiago.

Coenura albopunctata Schiner, 1868: 77 . Type locality: Chile. Type: ♂, deposited in Vienna Natural History Museum. Pelecorhynchus darwini Ricardo, 1900: 102 . Type locality: Chile. Type: ♀, deposited in British Museum (Natural History).

Material examined. Región Metropolitana: 1 ♀ Santiago, Chile Central without date, col. Germain; Región de La Araucanía: 1 ♂ Cautín, Temuco I.1956. no col.; 1 ♂ Cautín, Toltén 20.I.1955 col. H. Toro; Región de Los Lagos: 1 ♀ Llanquihue, Frutillar 10.II.1966 col. J. Silva G. & S. Valenzuela G; 1 ♀ Llanquihue, Parque Nacional Vicente Pérez Rosales 31.I.1992. col. G. Cerda.

Diagnosis and comments. Body color black. Scutum with two parallel longitudinal yellowish stripes. Scutellum black with golden yellow pilosity on the distal margin ( Fig. 1 ). Pleura brown with long abundant yellow pilosity on anepimeron and anepisternum. Wing infuscated. Abdomen black without white spots on tergites 1, 2 and 3, tergite 4 with a pair of rectangular white spots reaching the lateral margin. This species differs from the other species of Pelecorhynchus in the following characters: tergites 1, 2 and 3 without white spots, and with a pair of rectangular white spots on tergite 4. The latter character also occurs in P. elegans , but P. elegans has a pair of central white spots on the tergites 2 and 3. Mackerras & Fuller (1942) considered P. biguttatus a valid species; Philip (1968) reviewed the fragments of the type in the MNHNS of Santiago and considered it a variety of P. elegans . However, with the study of additional material, differences were observed that justify the treatment of P. biguttatus as a distinct species.

Description. Female (N = 3; length = 17.0 – 18.0 mm) Head: eyes black without color pattern when dry, bare. Occiput with yellowish hairs. Frons with brown grayish pruinosity, with short black hairs, parallel-sided. Parafacial with gray pruinosity and short black pilosity. Ocellar triangle blackish with black hairs, and with three ocelli ( Fig. 2 ). Posterior border of the head with gray pruinosity and short black hairs, brownish near the margin. Clypeus convex with gray pruinosity and long black hairs. Gena with gray pruinosity and yellow hairs, continuous with those of the occiput and beard yellow. Antennal scape and pedicel with blackish pruinosity, and short black hairs; first flagellomere brown-blackish; apical flagellomeres blackish. Maxillary palpus short brown, with short and abundant black hairs. Proboscis dark brown almost equal to the length of the head.

Thorax: scutum black with short and sparse black hairs, with two parallel longitudinal yellowish stripes. Scutellum black, with black hairs on disc and golden yellow hairs on the distal margin. Pleura with brown pruinosity, covered with long abundant yellow pilosity on anepimeron and anepisternum, katepimeron with brown hairs; katepisternum with black hairs. Legs dark brown with short black hairs. Coxae with pruinosity similar to pleura, posterior coxae with long whitish hairs on top. Wing infuscated orange mainly in the costal margin.

Abdomen: black dorsally, shining with sparse black hairs on all tergites; tergites 1, 2 and 3 without white spots; tergite 4 with a pair of rectangular white spots reaching the lateral margin. Sternites 2 and 3 each with a pair of rectangular white spots near lateral margin of the segment; sternite 4 with a band.

Male (N = 2, length: 16.0 – 18.5 mm). Head: eyes black, bare, holoptic. Ocellar triangle with black hairs and three ocelli. Posterior border of the head with gray pruinosity, and short black hairs. Occiput with long abundant yellow hairs. Clypeus convex with gray pruinosity, and long and abundant black hairs on surface. Gena with gray pruinosity and yellow hairs continuous with those of the occiput, beard orange. Scape and pedicel with dark gray pruinosity, and long black hairs. Flagellomeres dark brown. Maxillary palpus short brown darker than female, with abundant pilosity black. Proboscis and labellum dark brown, with few black hairs ( Fig. 3 ).

Thorax: scutum black with short and sparse black hairs, with two parallel longitudinal yellowish stripes. Scutellum black, with black hairs on disc and long golden hairs on distal margin ( Fig. 3 ). Pleura with brown pruinosity and long yellow hairs more abundant than female; katepisternum with some yellowish hairs, distally. Legs dark brown. Wing infuscated orange mainly in the costal margin ( Fig. 4 ).

Abdomen: black dorsally, shining with sparse black hairs on all tergites; tergites 1, 2 and 3 without spots; tergite 4 with a pair of rectangular white spots reaching the lateral margin of the segment. Sternites shining, with sparse black hairs, although on the spots with white hairs; sternites 2 and 3 each with a pair of white spots on each segment; sternite 4 with white band ( Fig. 5 ). Terminalia ( Fig. 6 ). Cerci one-segmented and prominent, lobate, apically rounded with small setae. Hypoproct about as long as wide, much longer than more dorsally situated cerci; posterior margin with a broad, shallow, v-shaped emargination. Epandrium long and broad, rectangular and strongly arched. Gonocoxite developed, large and curved, apically rounded, setose. Gonostylus tapering towards the apex, hooked near the apex, and a small protuberance ventrally sharp; medially with a prominent lobe projects beyond the medial, setose. In dorsal view, aedeagus short and narrow with two long curved hooks sharp, and the space between the hooks is narrow, and bears no spine.

Geographic distribution. Chile (Región Metropolitana to Región de Los Lagos) ( Fig. 7 ).

Figures

FIGURE 7. Geographic distribution of Pelecorhynchus biguttatus (Philippi, 1865).

FIGURES 1 – 6. Pelecorhynchus biguttatus (Philippi, 1865). 1. Adult male. 2. Head of female in frontal view. 3. Thorax and abdomen in dorsal view. 4. Head and thorax of male in lateral view. 5. Abdomen in lateral view. 6. Gonocoxites in dorsal view. Scale bar = 1 mm.