Macrurohelea bassoi, 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 : 447-450

Macrurohelea bassoi n.sp.

( Figs. 1–7 , 37–38 )

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Diagnosis. Females: the only species with a dark brown thorax and contrasting yellowish legs and abdomen; halter pale, transparent; and abdominal segment 9 greatly elongate. Males: the only species with a crescent-shaped tergite 10; gonocoxite stout with pointed basomesal tubercle; gonostylus abruptly curved at mid-length, distal ½ highly modified with inner mesal hump and broad foot-shaped apex; parameres with distal halves closely approximated, nearly straight, basal arms tapered distally, recurved 120° with inner slender external extension, apices with broad bulbous tips; and distal portion of aedeagus tongue-shaped with tip slightly notched mesally.

Female. Head ( Fig. 1 ) dark brown. Eyes narrowly separated medially by the width of 2 ommatidia, with numerous short interommatidial spicules. Antennal flagellum uniformly golden brown; flagellomere 1 with pair of apical sensilla coeloconica; flagellomeres 1–8 short, vasiform, 9–13 more elongate, 13 longest; antennal ratio 1.06–1.20 (1.13, n=10). Palpus pale brown, segment 5 slightly infuscated on distal 1/2; segment 3 with very shallow sensory pit (imperceptible in some specimens); segment 4 short, segment 5 as long as segment 3; palpal ratio 2.00–2.80 (2.30, n=10). Mandible with 8–10 coarse medial teeth. Thorax ( Fig. 2 ) uniformly dark brown; scutum with 2 stout prealar setae, 1 postalar seta; scutellum with 3 stout setae and 4 slender setae. Legs yellowish, hind tibia slightly darker; tarsomeres 3–5 slightly infuscated; tarsomere 1 of fore, hind legs with ventral row of palisade setae; tarsomeres 4 cordiform; tarsomeres 5 with pair of small claws slightly curved at tip; hind tarsal ratio 2.00 (n=10). Wing ( Fig. 3 ) membrane hyaline, slightly infuscated with dense microtrichiae; veins pale yellowish; 2 nd radial cell 2.44–3.33 (2.91, n=10)x longer than 1st; cell r 3 without intercalary veins; r-m crossvein slightly longer than petiole of M; costa with fringe of stout macrotrichia; wing length 1.30–1.42 (1.38, n=10) mm, width 0.58–0.63 (0.60, n=10) mm; costal ratio 0.72–0.76 (0.73, n=10). Halter pale. Abdomen ( Fig. 4 ) yellowish. Segment 9 greatly elongate, 10 elongate but much shorter than 9, both segments bent anteroventrally; sternite 8 lightly sclerotized with a short, rounded, posteromedian excavation. Two ovoid, slightly unequal-size spermathecae with moderately long, slender necks, measuring 54–70 (65, n=7) by 45–54 (48, n=7) µm, 50–66 (58, n=7) by 43–48 (45, n=7) µm, necks 9 µm long.

Male. Similar to female with the following notable sexual differences. Head ( Fig. 5 ). Eyes narrowly separated medially (visible in the male paratype; the top of the head is fractured in the holotype). Antennal flagellum with flagellomeres distinctly separated; flagellomeres 2–8 vasiform, 9–10 slightly elongate, 11–13 greatly elongate; antennal ratio 0.72–0.80 (0.76, n=3). Palpus similar to female, moderately short; segment 3 with few sensilla on surface; palpal ratio 2.70–3.00 (2.90, n=3). Thorax similar to female. Legs brown, tarsal claws small, nearly straight with bifid tips. Wing ( Fig. 6 ) narrower than female, with darker, well defined posterior veins; 2 nd radial cell shorter than female, only 1.5x longer than 1 st; wing length 1.32–1.48 (1.39, n=3) mm, width 0.49–0.51 (0.50, n=3) mm; costal ratio 0.64 (n=3). Abdomen dark brown. Genitalia ( Fig. 7 ). Tergite 9 triangular, extending 0.70 length of gonocoxites, with blunt apex. Tergite 10 crescent-shaped, extending to almost the level of apex of gonocoxites; apicolateral process minute, with medium-size seta; cercus slender, finger-like, setose. Sternite 9 2.7x broader than long, posteromedian margin slightly convex. Gonocoxite stout, 1.45x longer than wide, with prominent basomesal tubercle with pointed tip; gonostylus stout, 0.85 length of gonocoxite, abruptly curved at mid-length, distal ½ highly modified with inner mesal hump and broad foot-shaped apex. Parameres ( Fig. 37 ) separate; basal apodeme slender, arcuate, directed posterolaterally, anterior margin with heavily sclerotized colon-shaped process directed posteriorly; distal portion nearly straight, basal 2/3 broad, abruptly tapering distally, tip bulbous. Aedeagus ( Fig. 38 ) elongate, tongue-shaped, slightly shorter than basal width; basal arms broad basally, widely spaced at bases, apex narrowed, recurved, heavily sclerotized; basal arch V-shaped extending 0.25 of total length (shorter and slightly concave in one paratype); distolateral extension hyaline with lateral margins slightly divergent, with broad, rounded and slightly mesally notched tip.

Distribution. Argentina, in Nothofagus forests of Río Negro and Chubut provinces.

Type material. Holotype male labeled “ Holotype Macrurohelea bassoi Spinelli, Ronderos & Grogan ”, “ Argentina, Río Negro, El Bolsón , 41°57’53.72”S, 71°32’7.22”W, 29-XI-1999, G. Spinelli, at light” ( MLPA) . Paratypes, 2 males, 19 females, as follows: allotype female and 15 other females with same data as holotype; Río Negro, Parque Nacional Nahuel Huapi, río Ñireco , 41º11’51.9’’S 71º19’40.5’’W, 962 m, 18-II-2007, A. Garré – F. Montes de Oca, Malaise trap , 4 females; Chubut, Parque Nacional Los Alerces , 42°51’59.81”S, 71°36’4.76”W, L. Quate, Malaise trap , 1 male; Chubut, Puesto de Gendarmería “El Triana”, cerro Galera , 45°46’50’’S, 71°43’56’’W, 670 m, 2-XII-2002, G. Spinelli , 1 male, aerial net.

Derivation of specific epithet. We are pleased to name this new species after Dr. Néstor G. Basso of Centro Nacional Patagónico, Puerto Madryn, Argentina, for his friendship and companionship during several collecting trips in Patagonia.

Discussion. This new species keys to couplets 8 (females) and 16 (males) of M. irwini Grogan & Wirth in the key to Neotropical Macrurohelea by Spinelli & Grogan (1990). Males of M. bassoi n. sp. differ from males of M. irwini by the crescent-shaped tergite 10, the highly modified gonostylus that is abruptly curved at mid-length, the distal ½ is highly modified with an inner mesal hump and broad foot-shaped apex (gonostylus much shorter, narrower with a curved sharply pointed apex in M. irwini ); parameres separate with bulbous apices (parameres fused basally, slender, divergent distally with apices bent at 90º in M. irwini ); and, aedeagus slender, elongate with apex rounded and slightly notched mesally (aedeagus short, triangular with very long basal arms that are doubly recurved in M. irwini ). Females differ from those of M. irwini by the contrasting coloration between their dark brown thorax and their yellowish legs and abdomen.

Females and males of this new species were collected on the same date at the type-locality. Although the two sexes differ in the coloration of their legs and abdomen, their wings are nearly identical with the usual sexual differences such as the shorter 2 nd radial cell in males.

Figures

FIGURES 1–7. Macrurohelea bassoi n. sp. Allotype female, 1–4. Holotype male, 5–7. 1, 5 head. 2 thorax. 3, 6 wing. 4 tip of abdomen. 7 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.