Atrichopogon (Meloehelea) monomorphicus, Marino, Pablo I., Tóthová, Andrea & Spinelli, Gustavo R, 2011

Marino, Pablo I., Tóthová, Andrea & Spinelli, Gustavo R, 2011, Two new Patagonian species of Atrichopogon (Meloehelea) (Diptera: Ceratopogonidae), Zootaxa 2777, pp. 61-68 : 65-67

Atrichopogon (Meloehelea) monomorphicus new species

Diagnosis. Male adult: only extant species of Atrichopogon (Meloehelea) from Patagonia without secondary sexual dimorphism. Female adult: only extant species of Meloehelea in the Neotropical Region without macrotrichia on cua1 and anal cell.

Description. Male adult: Head: Brown ( Fig. 3 A). Ommatidia with interfacet pubescence, broadly abutting medially for length of 1–2 ommatidia. Antenna with plume not developed; flagellomeres separate, proportions as shown in Fig. 3 A; flagellomeres 1–8 subspherical, 10–13 elongated; flagellomere 13 with apical projection slightly not constricted basally; AR 3.34 (3.20–3.45, n=4). Maxillary palpus with third segment slender, with well-developed pit located near midlength ( Fig. 3 B); segments 4, 5 separate; PR 3.10 (2.91–3.30, n=4). Proboscis short, mouthparts length 0.17 (0.16–0.18, n=4) mm; head width/mouthparts length 1.76 (1.74–1.78, n=4). Thorax ( Fig. 3 C): dark brown with very faint, narrow lateral pale stripes; scutum with setae arising directly from surface; paratergite with 1 seta. Anepisternum well developed, strongly bilobed posteriorly. Legs light brown; hindtibia not expanded at apex; hindtibial spur length less than width of hindtibia at midlength; hindtibial comb with 8 spines; prothoracic TR 2.98 (2.80–3.11, n=4); mesothoracic TR 2.64 (2.50–2.78, n=4); metathoracic TR 2.45 (2.36–2.55, n=4); claws curved, bifid at tip, empodia present. Wing ( Fig. 3 D) without pattern of pigmented membrane, with abundant macrotrichia on r3 and few on m1; wing length 1.06 (1.02–1.08, n=4) mm; breadth 0.44 (0.42–0.46, n=4) mm; CR 0.66 (0.65–0.67, n=4). Halter white.

Abdomen: tergites uniformly brown. Sternites more or less similarly rectangular shaped. Genitalia ( Fig. 3 E): segment 9 about equal in width to segment 8, tergite 9 short, extending midlength of gonocoxite, posterior margin rounded. Sternite 9 with posterior margin slightly concave, with single row of 10 setae. Gonocoxite without medial lobe, moderately stout, 1.7 times longer than greatest breadth; gonostylus 0.8 as long as gonocoxite, nearly straight, apex gently curved, pointed, subapical stout tooth. Aedeagal-parameral complex broad; posterodorsal projection tapering to cap-like process; lateral margins of posteroventral process sinuate, posteromedial portion slightly notched. Cercus short, lobe-like, ventral to tergite 9.

Female adult: As for male, only with sexual differences. Head: antenna dark brown, with flagellomeres 1–8 slightly broader than long; flagellomeres 9–13 elongated, proportions as shown in Fig. 4 A, AR 2.19 (2.18–2.21, n=2), PR 3.55 (3.40–3.70, n=2); mouthparts length 0.165 (0.154–0.176, n=2) mm, head width/mouthparts length 1.80 (1.62–1.96, n=2). Mandible well developed, with 22 (20–26, n=2) small teeth ( Fig. 4 B). Laciniae with pale indistinct teeth, without spicules. Thorax: Legs ( Fig. 4 C) light brown; hindtibial comb with 7 spines; prothoracic TR 2.89 (2.89–2.90, n=2); mesothoracic TR 2.79 (2.78–2.80, n=2); metathoracic TR 2.56 (2.55–2.58, n=2). Wing ( Fig. 4 D) without pattern of pigmented membrane, with macrotrichia very abundant in r3 and m1, 2– 3 in m2, and 0– 1 in cua1; radial cells with broad lumen, second 4.25 times longer than first; wing length 1.13 (1.08–1.18, n=2) mm; breadth 0.51 (0.50–0.52, n=2) mm; CR 0.70 (0.69–0.71, n=2).

Abdomen ( Fig. 4 E): tergites uniformly brown. Sternite 8 without elongate, curved setae. Two subequal ovoid spermathaecae, smaller measuring 68 x 59 µm, neck 8 µm and larger collapsed, each with moderately elongated neck. Cercus light brown.

Distribution and bionomics. Atrichopogon monomorphicus is known only from the type-locality at Nahuel Huapi National Park of Argentina, at elevations of 962 m. This species inhabits grassy steppes of the Subandean district ( Leon et al., 1998), where the semiarid Patagonia contact with the Subantarctic province. The Subandean district is characterized by rainfall exceeding 300 mm per year, joined the eastern sector of the deciduous forests of Nothofagus in a wide ecotone in form of patches or mosaics.

Specimens examined. Types: Holotype male, allotype female, 3 males and 1 female paratypes, Argentina, Parque Nacional Nahuel Huapi, Río Nireco, 41º11’51.9”S 71º19’40.5”W, 962 m, 23.i/ 18.ii.2007, A. Garré – F. Montes de Oca, Malaise trap.

Taxonomic discussion. This new species is the only New World Atrichopogon (Meloehelea) without secondary sexual dimorphism. However, this is not an uncommon characteristic of Atrichopogon spp., since it can be observed in the following American species: A. inacayali Spinelli & Marino from Patagonia, A. homofacies Spinelli and A. carpinteroi Marino & Spinelli from northeastern Argentina, and A. asuturus Borkent & Picado and A. tirzae Borkent & Picado from Costa Rica.

The male genitalia of A. (M.) monomorphicus is very similar to that of A. (M.) chilensis but the 9th tergite is slightly elongated and almost reaches the apical part of gonocoxite in the last species. However, females of both species differ in the number of mandibular teeth (26–33 in A. chilensis ) and in the number of macrotrichiae on wing membrane (more than 60 in r3, more than 50 in m1, more than 30 in m2, 15 in cua1 and 29 in anal cell in A. chilensis ).

Derivation of specific epithet. The name refers to the similar morphology of males and females in the extragenital characters.

Figures

FIGURE 3. Male of Atrichopogon (Meloehelea) monomorphicus Marino, Tóthová & Spinelli, new species. A—head (dorsal view), B—mouthparts (dorsal view), C—thorax (dorsal view), D— wing, E—hypopygium (ventral view).

FIGURE 4. Female of Atrichopogon (Meloehelea) monomorphicus Marino, Tóthová & Spinelli, new species. A—head (dorsal view), B—mouthparts (dorsal view), C—thorax (lateral view), D— wing, E— terminal abdominal segments and spermathecae (ventral view).