Macrurohelea donatoi, Spinelli & Ronderos & Grogan, 2022

Spinelli, Gustavo R., Ronderos, Maria M. & Grogan, William L., 2022, Five new species in the predaceous midge genus Macrurohelea Ingram & Macfie from Argentina, and descriptions of the previously unknown males of M. kuscheli Wirth and M. monotheca Spinelli & Grogan (Diptera: Ceratopogonidae), Zootaxa 5093 (4), pp. 445-464 : 450-452

Macrurohelea donatoi n. sp.

( Figs. 8–14 , 39–40 )

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Diagnosis. Females: the only species with flagellomeres 9–12 elongate, 13 greatly elongate, nearly twice as long as 9; thorax and legs dark brown; wing membrane and cells infuscated brown, slightly darkest on distal ½ of cell r 3 and r-m crossvein; cell r 3 without intercalary vein; halter dark brown; two ovoid, slightly unequal-size spermathecae with long slender, tapered necks. Males: the only species with minute apicolateral process on tergite 9 with a short inner peg; distal portion of parameres nearly straight, fractured subapically and narrowly separated from short, triangular tip.

Female. Head ( Fig. 8 ) dark brown. Eyes separated medially by width of 3 ommatidia, with numerous short interommatidial spicules. Antennal flagellum dark brown; flagellomere 1 with pair of apical sensilla coeloconica; flagellomeres 2–8 short, vasiform, 9–13 elongate, 13 longest, nearly twice as long as 9; antennal ratio 1.16–1.36 (1.28, n=7). Palpus dark brown; segment 3 with shallow sensory pit; segment 4 very short, segment 5 nearly as long as segment 3; palpal ratio 2.00 (n=7). Mandible with 9–12 coarse medial teeth. Thorax ( Fig.9 ) uniformly dark brown. Scutum with 2 stout prealar setae, 1 postalar seta; scutellum with 4 stout setae. Legs dark brown; ventral palisade setae on tarsomere 1 of fore, hind legs; hind tarsal ratio 2.60–2.80 (2.68, n=3); tarsomeres 4 cordiform; tarsomeres 5 with pair of small claws slightly curved at tips. Wing ( Fig. 10 ) membrane infuscated brown, slightly darkest on r-m crossvein and distal ½ of cell r 3, surface with minute microtrichia; veins dark brown; 2 nd radial cell 2.00–3.45 (2.52, n=7)x longer than 1st; cell r 3 without intercalary vein; costa with very short macrotrichia; r-m crossvein as long as petiole of M; wing length 1.57–1.80 (1.70, n=7) mm, width 0.66–0.80 (0.72, n=7) mm; costal ratio 0.71–0.75 (0.72, n=7). Halter dark brown. Abdomen ( Fig.11 ) dark brown. Segments 9–10 elongate, bent forward ventrally; sternite 8 heavily sclerotized with a prominent semi-circular medioposterior sclerite and shallow posteromedian U-shaped excavation. Two ovoid, slightly unequal-size spermathecae with long, slender, tapered necks, measuring 80–82 (80, n=2) by 54–58 (56, n=2) µm, and 70–80 (75, n=2) by 46–54 (50, n=2) µm, necks ca. 20 µm long.

Male. Similar to female with the following notable sexual differences. Head ( Fig. 12 ) dark brown, slightly flattened dorsoventrally. Eyes separated medially by width of 3 ommatidia. Antennal flagellum with flagellomeres distinctly separated; plume very dense, extending to mid-length of flagellomere 12; antennal ratio 0.61. Palpus moderately short; segment 5 nearly as long as segment 3. Tarsal claws small, nearly straight with bifid tips. Wing ( Fig.13 ) similar to female but narrower; 2 nd radial cell 1.70x longer than 1st; cell r 3 with very faint intercalary vein; wing length 1.74 mm, width 0.59 mm; costal ratio 0.68.Genitalia ( Figs.14 , 39–40 ).Tergite 9triangular, extending 0.80 length of gonocoxites. Tergite 10 very short, apicolateral process minute with a short peg; cercus slender, elongate, finger-like with sparse long setae. Sternite 9 stout, 2.70x broader than long, with a shallow, narrow posteromedian excavation. Gonocoxite stout, 1.45x longer than broad; gonostylus 0.85 length of gonocoxite, moderately curved on distal 1/2, apex broadly rounded. Parameres ( Fig. 39 ) separate; basal apodeme slender, directed laterally, anterior margin with short, stout tubercle, distal portion nearly straight, tapering gradually distally, fractured subapically, narrowly separated from short, triangular tip. Aedeagus ( Fig. 40 ) triangular, slightly broader than long; basal arm slender, heavily sclerotized, directed laterally; basal arch irregular, extending 0.20 of total length; lateral margins convex, tapering distally to heavily sclerotized, subapical, U-shaped process; tip ovoid, lightly sclerotized.

Distribution. Known only from Tierra del Fuego, Argentina.

Type material. Holotype male, labeled “ Holotype Macrurohelea donatoi Spinelli, Ronderos & Grogan ”, “ Argentina, Tierra del Fuego, río Tristén y ruta nacional 3, 54°43’59.24”S, 67°54’48.08W, 7-XII-2005, G. Spinelli, aerial net ( MLPA); allotype female and 6 other female paratypes, Tierra del Fuego, ruta complementaria J, km 73.5, 54°55’36”S, 66°57’28.6W, 113 m, 2/ 6-XII-2008, Spinelli–Donato, Malaise trap ( MLPA).

Derivation of specific epithet. We are pleased to name this new species after Dr. Mariano Donato of the Instituto de Limnología “Dr. Raúl A. Ringuelet”, La Plata, Argentina, for his friendship and companionship during several collecting trips to Patagonia.

Discussion. The holotype male of this new species is very similar to M. yamana Spinelli & Grogan , a species that also inhabits the island of Tierra del Fuego. However, in M. yamana the gonocoxite is longer, the gonostylus is also longer, more slender with a broader apex, the parameres are fractured beyond mid-length and their apices are curved distally and greatly divergent; the aedeagus is slender with a concave basal arch and the distal portion lacks the subapical, U-shaped process, and has a slightly broader apex. Females of both species are nearly indistinguishable, but the wing is slightly smaller in M. yamana (wing length 1.46–1.54 mm vs. 1.57–1.80 mm in M. donatoi ), the membrane is only slightly infuscated including the distal ½ of cell r 3 which also lacks an intercalary vein, and the spermathecae are smaller (45–53µm long by 38µm wide vs. 70–82 µm long by 46–58 µm wide in M. donatoi ) and not as greatly tapered above their necks.

The holotype of M. donatoi also resembles males of M. monotheca Spinelli & Grogan , but in that species the basal arms of the aedeagus are stouter and their lateral margins are straight, the posteromedian excavation of sternite 9 is shallow, and the apicolateral process of tergite 9 has a medium-size seta instead of a peg.

Figures

FIGURES 8–14. Macrurohelea donatoi n. sp. Allotype female, 8–11. Holotype male, 12–14. 8, 12 head. 9 thorax. 10, 13 wing. 11 tip of abdomen. 14 genitalia. Scale bars = 0.05 mm.

FIGURES 37–42. Macrurohelea bassoi n. sp. Holotype male, 37–38. Macrurohelea donatoi n. sp. Holotype male, 39–40. Macrurohelea kuscheli Wirth, male, 41–42. 37, 39, 41 parameres. 38, 40, 42 aedeagus.