Acellomyia puyehue, González, 2017

González, Christian R., 2017, The genus Acellomyia González, a new taxonomic arrangement of its species and descriptions of a new genus and two new species from southern South America (Diptera: Tabanidae: Diachlorini), Zootaxa 4337 (4), pp. 523-539 : 532-535

Acellomyia puyehue sp.n.

( Figs. 5a–k )

Type locality. Antillanca , Osorno Province, Chile.

Diagnosis. Medium-sized species (13.5–14.5 mm). Body color brown ( Fig. 5a ). Eye without bands, with abundant short gray ommatrichia. Frons broad grayish, slightly divergent. Basal callus rounded, without dorsal projection, touching eyes. Subcallus brownish with abundant, short gray setae towards the edges. Antenna brownish. Maxillary palpus elongated, yellowish, bearing yellowish pruiniscence and short whitish setae. Mesonotum dark gray, with long brown and whitish setae, bearing two narrow longitudinal pale stripes only on the anterior part. Wing lightly smoky, without appendix on R4. Abdomen light brown dorsally, with long brownish setae, posterior border of tergites 1–6 with distinct narrow grayish hind margins and grayish setae. Sternites brownish, mostly grayish haired.

Description (Holotype ♀).

Female. Head. Eye dark grayish, without bands, with abundant short gray ommatrichia. Frons grayish, with brownish pruiniscence on vertex, bearing abundant short black setae. Frons wide, slightly divergent, frontal index 1.82; ocellar triangle vestigial, ocelli absent. Basal callus shining light brown, rounded, without dorsal projection, touching eyes ( Fig. 5b ). Posterior border of the head gray with short whitish setae; vertex with erect black and whitish setae. Subcallus covered with brownish pruiniscence, and with abundant, short gray setae towards the edges. Clypeus and genae with brownish pruiniscence, genae with long whitish setae, clypeus bearing long whitish setae on each side below antennae. Beard with long whitish setae ( Fig. 5c ). Scape of antenna brown, and with short and long black setae on dorsal and ventral surface. Pedicel darker and with very short black setae. First flagellomere dark brown not angulate on dorsal surface, flagellomeres concolorous ( Fig. 5d ). Maxillary palpus elongate, yellowish, bearing yellowish pruiniscence, and with abundant short whitish setae ( Fig. 5e ). Proboscis dark brown, labellum concolorous, large and fleshy. Thorax. Mesonotum dark gray, with long dark brown and whitish setae only on the anterior part of the mesonotum, bearing two narrow longitudinal pale stripes reaching transverse suture. Postpronotal lobe pale gray, with long brown setae. Scutellum dark gray, with long dark setae on the disc and long brown setae, especially at the base ( Fig. 5f ). Pleura coated with gray pruiniscence, with long whitish setae, more dense and long on anepimeron. Legs brownish, coxa grayish with a few long whitish setae.

Femur with long whitish setae, tibia shorter and black. Tarsus with abundant short black setae. Wing lightly smoky, without appendix on R4 ( Fig. 5g ). Basicosta bare. Halter light brown, knob lighter. Calypter concolorous with base of wing. Abdomen. Light brown dorsally, with long, brownish setae, posterior border of tergites 1–4 with distinct narrow grayish hind margins and grayish setae. Tergites 3–6 with grayish pruiniscence, and median posterior spots. Tergite 7 with pruiniscence, pale grayish pilose ( Fig. 5h ). Sternites brownish, mostly grayish haired. Terminalia. Cerci with apex almost rounded; tergite 10 subrectangular, with the tip rounded; tergite 9 subtriangular, with long setae (Fig. fi). Gonapophysis with border concave and sinuous; sternite 8 with narrow base ( Fig. 5j ). Genital fork with narrow base, concave and short sperm pumps ( Fig. 5k ).

Male: Unknown.

Acellomyia

A. casablanca A. fontanensis A. mapuche A. paulseni A. puyehue

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, <<B <B <B <4 6! 2 6! 2 6! 2 6 6 Variability. Length 13.5–14.5 mm; wing 13.5–14.0 mm; frontal index 1.81–1.87 (n = 9). There is some variation, the length of the median projection of the basal callus (longer in some specimens), and color of abdominal terga.

Distribution. Chile (Osorno).

Type-material. Holotype ♀, CHILE, Osorno Province , Antillanca (40º46'35''S / 70º12'16''W), 2.II.1992, C.R. González ( IEUMCE) . Paratypes: 3 ♀ with same dates (IEUMCE); 5 ♀ Port Puyehue , 19.I.1969, L.E. Peña ( IEUMCE) .

Etymology. The specific name is a noun in apposition taken from the type locality.

In addition to the characters mentioned in the descriptions of species of Acellomyia others differences are show in table 2.

Comments. The newly described Acellomyia species exhibit generalized features characteristic of the genus. There are differences in the shape of the basal callus, ocular ommatrichia and abdominal triangles, but the morphological characters were successful in delimiting these species from southern Chile from other Acellomyia .

A. casablanca sp.n. and A. puyehue sp.n. are members of a group of species occurring in the southernmost region of South America, especially in the Andes mountains. The distribution of these species was affected during the last glacial maximum (14 0 0 0 yr BP), the species moving to lower altitudes until about 11 0 0 0 yr BP, when deglaciation of the Andean valleys had reached the current state; this change in distribution left the western slopes of the Andes open for colonization ( Mercer 1976; Ashworth & Hoganson 1987). Based on collection records from Chile and other countries, Acellomyia and Dasybasis are part of the earliest diverging group within the tribe Diachlorini ( Fairchild 1969) , with dominant forms in colder zones, and used wetland formations present throughout the Andes to shelter and disperse, as has been shown for different groups of plants and animals ( Villagrán et al. 1983; González 1999). With the retreat of the ice, these groups became widely distributed in the Valdivian forest, after strong quaternary climatic oscillations.

Figures

FIGURE 5. Holotype female of Acellomyia puyehue sp. n. a. Habitus (scale bar = 5.0 mm); b. Head in frontal view; c. Head in lateral view; d. Antennae (scale bar = 0.5 mm); e. Maxillary palpus (scale bar = 0.5 mm); f. Mesonotum in dorsal view; g. Wing; h. Abdomen in dorsal view; i. Cerci, tergite 9 and 10; j. Gonapophysis and sternite 8, dorsal view; k. Genital fork and spermathecal ducts (scale bar = 1 mm).