Pelecorhynchus kroeberi ( Lindner, 1925 )

González, Christian Raúl & Elgueta, Mario, 2022, Redescription of Pelecorhynchus kroeberi (Lindner), a Patagonian species rediscovered after more than 100 years in Chile (Diptera: Pelecorhynchidae), Papéis Avulsos de Zoologia 62, pp. 1-6 : 2-4

Pelecorhynchus kroeberi ( Lindner, 1925) Figs. 1-9

Coenura kroeberi Lindner, 1925: 23 .

Type locality: Chile, Magallanes, Punta Arenas. Holotype ♀ ( ZMUH),destroyed according to Pechuman (1967:555).

References: Kröber, 1930a: 154 (as Coenura ); Kröber, 1930b: 114 (in key), 115; Kröber, 1934: 232 (catalog); Mackerras & Fuller, 1942: 72 (in key, as Pelecorhynchus ), 74 (comments); Stuardo, 1946: 67 (catalog); Pechuman, 1967: 555 (comments about holotype); Philip, 1968: 2 (catalog); Pino, 1968: 118 (comments); Pino, 1969: 8 (list); Coscarón & Papavero, 2009: 5 (catalog); Llanos et al., 2015: 198 (redescription); González & Elgueta, 2020: 159 (catalog).

Material examined: 1♀, Chile, Región de Aysén, Provincia de Aysén 46°40′11.9″S, 74°00′54.0″W, 02/ December/2021 - 12/January/2022, R.I. Madriz Coll., Malaise trap, C.R. González Det., Colección Nacional de Insectos, Museo Nacional de Historia Natural, Área de Entomología, Santiago, Chile (MNNC).

Diagnosis: Body color dark-brown.Eyes bare.Frons moderately wide and slightly divergent. Ocellar triangle with three ocelli. Clypeus with brownish pruinescence, laterally with long and dense black hairs. Antennae brownish. Palpus with brown pruinescence, stout, relatively flat, as long as ¼ of the proboscis.Mesonotum dark-brown,with short and dense brown-reddish hairs and a pair of submedial, nearly parallel pale vittae; scutellum dark brown, with long brown hairs on distal margin. Legs mostly brown with short black hairs. Wings hyaline. Abdomen dark-brown dorsally in the background; tergite 1 with a pair of small white-yellowish spots, tergites 2-4 with a pair of circular and broad lateral white-yellowish spots.

Description: Female (length = 21.5 mm; wing length = 16.5). Body color dark-brown ( Fig. 2 ).

Head: Eyes dark-brown, bare, without color pattern. Frons moderately wide and slightly divergent ventraly, with brownish pruinescence and medium black hairs. Vertex with brown pruinescence and short black and brown hairs and few reddish hairs ( Fig. 3 ). Ocellar triangle dark-brown, with short black hairs, three ocelli. Gena with golden-brown pruinescence, and with long brownish and goldish hairs. Clypeus with brownish pruinescence, laterally with long and dense black hairs, medially hairs are shorter and less abundant. Antennal scape brown, with short brownish hairs, pedicel darker. First flagellomere and following three flagellomeres light brown, darker on distal half apically ( Fig. 4 ). Palpus two-segmented with brown pruinescence, stout, relatively flat, as long as ¼ of the proboscis, with long and scarce black hairs ( Fig. 3 ). Proboscis brown, labellum small ( Fig. 3 ). Occiput with light brown pruinescence and black hairs on dorsal edge.

Thorax: Mesonotum dark-brown, with short and dense brown-reddish hairs and a pair of submedial, nearly parallel pale vittae. Postpronotal lobes dark-brown, with long brown-reddish hairs. Scutellum dark brown, with long brown hairs on distal margin ( Fig. 5 ). Pleura coated with gray pruinescence and long yellowish hairs; anepisternum and anepimeron with long yellowish hairs; katepisternum and katepimeron bare ( Fig. 6 ). Legs mostly brown with short black hairs, except for coxa grayish with long yellowish hairs, femur with light brown hairs; tibia concolorous with shorter light brown and black hairs.Wings hyaline, darker on costal and subcostal cells, cell r₅ widely open; veins Sc and R₁ bare ( Fig. 7 ). Basicosta bare. Halter whitish, darker at apex.

Abdomen: Dark-brown dorsally in the background, distal margin of tergites densely covered by brown-reddish hairs; tergite 1 with a pair of small white-yellowish spots, tergites 2-4 with a pair of circular and broad lateral white-yellowish spots, occupying most of the tergite, triangular ( Fig. 8 ). Sternites mostly pale brown, without spots and with scarce brownish hairs.

Terminalia: Cercus two-segmented, apical segment ovoid-shaped ( Fig. 9A ), and with posteroventral cercal lobes developed curved towards the median plane ( Fig. 9B ). Tergite 8 squared as long as wide ( Fig. 9A ). Tergite 9 widely divided, trianguliform. Tergite 10 small. Sternite 8 acuminated ( Fig. 9B ). Genital fork with a narrow base, neck wide basally and a long spine present on the comb. Three spermathecal ducts, mostly slender.

Distribution: Chile. Región de Aysén, Provincia de Aysén (46°40′11.9″S, 74°00′54.0″W, Western shore of Laguna San Rafael); Región de Magallanes: Provincia de Magallanes (Punta Arenas).

Comments: The genitalia of P. kroeberi is similar to the female genitalia described for other species of Pelecorhynchus (see Mackerras & Fuller, 1942; Nagatomi & Iwata, 1976; Kerr, 2010; Carmo & Santos, 2011), with the basal segment of cercus expanded, forming posteroventral lobe ( Carmo & Santos, 2011: 477, Fig. 9A ).This character has also been observed in species of Pelecorhynchidae ( Glutops Burgess ), Rhagionidae ( Chrysopilus Macquart , Pseudoerinna Shiraki , Rhagio Fabricius , Symphoromyia Frauenfeld), and Vermileonidae ( Vermileo Macquart ) ( Stuckenberg, 2001; Kerr, 2010). The similarity of the posteroventral lobes in Pelecorhynchus and could be interpreted as a synapomorphy of Rhagionidae + Pelecorhynchus (Pelecorhychidae) (see Santos, 2006).The shape of sternite 8, with the acuminate anterior margin, is an additional feature supporting Rhagionidae and Pelecorchynchidae as sister groups.

Figures

Figure 1. (A) Distribution record forP.kroeberi of holotype (circle) and specimen (triangle)in southern Chile.(B)Map showing location of sampling siteof P.kroeberi (Lindner) in LagunaSan Rafael,Region de Aysén,Chile.(C) Malaise trapthat captured P.kroeberi (Lindner).

Figure 2. Habitus of P. kroeberi (Lindner) female in lateral view. Scale bar = 1.0 mm.

Figure 3. Head of P. kroeberi (Lindner) female in frontal view. Scale bar = 1.0 mm.

Figure 4. Antenna of P. kroeberi (Lindner) female in lateral view. Scale bar = 0.5 mm.

Figure 5. Thorax of P. kroeberi (Lindner) female in dorsal view. Scale bar = 1.0 mm.

Figure 6. Thorax of P. kroeberi (Lindner) female in lateral view. Scale bar = 1.0 mm.

Figure 7. Wing of P. kroeberi (Lindner) female in dorsal view. Scale bar = 1.0 mm.

Figure 8. Abdomen of P. kroeberi (Lindner) female in dorsal view. Scale bar = 1.0mm.

Figure 9.Terminalia of P.kroeberi(Lindner)female.(A)Terminalia dorsalview.(B)Terminaliaventral view.Abbreviations:cerc:cercus;pvl:posteroventral lobe;spm dt: spermathecal duct;st8: sternite 8;tg 9: tergite 9. Scale bar = 0.1 mm.