Macropelopia (Bethbilbeckia) chilensis, Andersen, 2018

Andersen, Trond, 2018, Macropelopia (Bethbilbeckia) chilensis n. sp. (Diptera, Chironomidae) from Cajón del Maipo, Chile, Norwegian Journal of Entomology 65, pp. 85-90 : 86-89

Macropelopia (Bethbilbeckia) chilensis n. sp.

( Figures 1–10 ).

Type material: Holotype: Pharate male pupae, CHILE, Región Metropolitana, San José de Maipo, Cajon del Maipo , Baños Morales , 33.824151 oS 70.062993 oW, 1.835 m a.s.l., 18– 19 February 1999, drift net, leg. T. Andersen ( ZMBN) . Paratypes: 5 pharate male pupae, 3 pharate female pupae, 3 pupae exuviae, as holotype ( ZMBN); 1 pharate female pupa, CHILE, Región Metropolitana, San José de Maipo, Cajon del Maipo, Lo Valdes , Rio Volcán , 33.856273 oS 69.982294 oW, 2.540 m a.s.l., 10 November 1998, drift net, leg. T . Andersen ( ZMBN).

Etymology: Named after the country of origin.

Diagnostic characters: The male can easily be separated from the male of M. (B.) floridensis by having bi- to multiserial orbitals and a strong comb on hind tibia; M. (B.) floridensis has uniserial orbitals and lack comb on hind tibia. The pupa possesses the large, spine-like D 1 setae arising from prominent tubercles on tergites II– VII, which is characteristic for M. (B.) floridensis . However, the thoracic horn is somewhat triangular and curved and is more similar to the thoracic horn in some other Macropelopia (s. str.) species than in M. (B.) floridensis .

Description: Male (pharate male pupae) (n = 5, if not otherwise stated).

Coloration. Brown.

Antenna. Terminal flagellomere ( Figure 1 ) 96–115, 105 µm long; 27–33, 30 µm wide at base.

Head. Eye-bridge 4 ocelli wide. Inner verticals 10–14, 12, multiserial; outer verticals 8–13, 10, bito triserial; postorbitals 11–14, 12, bi- to triserial.

Thorax. Dorsocentrals irregularly biserial; acrostichals tri- to multiserial; scutellum with transverse row of 15–22, 18 strong setae and 7–13, 12 weaker setae anterodorsally; postnotum apparently with altogether about 13 (1) setae, biserial; other setae difficult to observe. Scutal tubercle apparently low, difficult to observe in the slides.

Wing. Not measurable.

Legs. Width at apex of fore tibia 73–77 (3) µm; of mid tibia 70–76, 73 µm; of hid tibia 80– 82, 81 µm. Spur of fore tibia 80–86 (3) µm long with 9–14 side teeth ( Figure 2 ); long spur of mid tibia 66–77, 73 µm long with 17–19, 18 side teeth, short spur 57–68, 63 µm long with 11–16, 14 side teeth ( Figure 3 ); long spur of hind tibia 80–89, 86 µm long with 6–9, 8 side teeth, short spur 57–65, 62 µm long with 9–12, 11 side teeth ( Figure 4 ). Fore tibia apparently without comb. Comb of hind tibia with 8 strong setae, longest 69–76, 73 (4) µm long; shortest 48–52, 50 (4) µm long. Claws on all legs long and slender, distally pointed, spinulate in basal 1/3.

Hypopygium ( Figures 5–6 ). Tergite IX with 9–13 (3) setae in single to partly biserial posterior row. Gonocoxite 154–160 (3) µm long; gonostylus slender, 139–146 (3) µm long; megaseta 12–14 (3) µm long.

Pupa (n = 8–10). Total length 5.25–6.98, 6.03 mm.

Coloration. Brown.

Cephalothorax. Thoracic horn ( Figure 8 ), somewhat triangular, curved; 372–448, 404 µm long; 140–176, 160 µm wide at its widest point; plastron plate 196–256, 214 µm long; external membrane with distinct spines; horn sac not quite filling horn lumen. Thoracic membrane with transverse ridges extending to median suture. Thoracic setae Dc 1 simple, pointed, about 60 µm long; Dc 2 not discernable; Sa simple, pointed, about 160 µm long.

Abdomen ( Figure 7 ). Scar on tergite I elongate and pigmented. Shagreen spines ( Figure 9 ) short, blunt, and partially serially arranged in groups of 2–4. Abdominal setae D 1 on tergites II–VII large, spine-like and arising from large, prominent tubercles; tergite II: D 1 100–128, 112 µm long, tubercle 88–120, 103 µm long measured along inner margin; tergite III: D 1 116–136, 127 µm long, tubercle 160–188, 174 µm long; tergite IV: D 1 140–160, 151 µm long, tubercle 192–236, 217 µm long; tergite V: D 1 140–160, 151 µm long, tubercle 212–256, 227 µm long; tergite VI: D 1 140–160, 153 µm long, tubercle 188–220, 199 µm long; tergite VII: D 1 136–164, 153 µm long, tubercle 112–136, 139 µm long. Remaining D and V setae of varying size; D 2 and D 3 on tergite III–V arising from small tubercles. Segments I–VI with 2 L setae; segment VII with 4 short LS setae; segment VIII with 5 LS setae, longest about the length of the segment.

Anal lobe ( Figure 10 ) 458–572, 515 µm wide, 580–669, 641 µm long. With simple spine shagreen laterally. Outer border with fringe of setae-like spinules gradually reduced to indistinct spines at the distal end; inner border divergent, without fringe, but with few, small, indistinct spines preapically in some specimens. Anal macrosetae arise from basal 1/4, about 0.75 times segment length.

Larva. Unknown.

Figures

FIGURES 1–6. Macropelopia (Bethbilbeckia) chilensis n. sp., male. 1. Terminal antennal flagellomere. 2. Tibial spur of fore leg. 3. Tibial spurs of mid leg. 4. Tibial spurs and comb of hind leg. 5. Hypopygium, dorsal aspect. 6. Hypopygium, ventral aspect.

FIGURES 7–10. Macropelopia (Bethbilbeckia) chilensis n. sp., pupa. 7. Abdominal tergites and anal lobe. 8. Thoracic horn. 9. Shagreen. 10. Anal lobe and male genital sac.