Dixella spinosa, Corrêa & Scarpa & Pinho & Gil-Azevedo, 2024

Corrêa, Caio Cezar Dias, Scarpa, Priscila Luiza, Pinho, Luiz Carlos & Gil-Azevedo, Leonardo Henrique, 2024, Three New Species Of Dixella Dyar & Shannon (Diptera: Dixidae) From Santa Catarina, Brazil, Zootaxa 5433 (3), pp. 321-338 : 331-334

Dixella spinosa sp. nov.

( Figs. 7–9 )

Type Material. HOLOTYPE: ♂ (slide)—[ MNRJ40910 ] BRAZIL, Santa Catarina, Praia Grande, Parque Nacional de Aparados da Serra, Rio do Boi , S29°12’06” W50°02’32”, 27/IX/2016, Hand net, LC Pinho et al. col. ( MNRJ) . PARATYPES: 1♂ (slide)—[ MNRJ40910 ] same data as holotype ( MNRJ) ; 1♀ (slide)—[ MNRJ40911 ] same data as holotype ( MZSP) ; 1♀ (slide)—[ MNRJ40920 ] same data as holotype ( MNRJ) .

Diagnosis. Adults with thorax light brown with dark brown stripes ( Fig. 7C ).Male with triangular or subtriangular gonostylus (lateral view) with scattered stout setae. Female with sternite IX undivided with broad lateral projections (both sides) ( Fig. 8A ).

Description. Male. Body length: 3.1 mm (n = 2) Head ( Fig. 7A ) uniformly brown with a row of setae on the dorsolateral portion, and setae around the eyes in the posterior portion. Antenna ( Fig. 7B ) light brown, setose, and 0.6x length of wing. Scape collar-like. Pedicel globose, 0.45x length of flagellomere I. Flagellum with 14 flagellomeres. Flagellomere I cylindrical, 1.5x length of flagellomere II. Flagellomere II smaller than flagellomere III. Flagellomeres III to XIV decreasing in length. Flagellomere XIV with pair of divergent apical setae. Clypeus light brown, short, 1.5x wider than long and ca. five setae in the apical portion. Maxillary palpus light brown and 5- segmented; maxillary palp V claviform. Maxillary palpus ratio (I–V): 1, 1.2, 2.9, 2.6, 3.5. Thorax ( Fig. 7C ). Scutum light brown with dark brown medial stripe enlarged anteriorly extending from anterior to medial portion, and dark brown lateral stripe extending from prescutal to prescutellar area. Acrostichal setae originating from anterior portion and reaching the medial portion; dorsocentral setae complete; antealar area with a row of three elongated setae. Antepronotum light brown. Postpronotum light brown with two setae. Anterior and posterior anepisternum brown with the dorsal portion pale. Katepisternum brown and bare. Anepimeron brown with the dorsal and antero-medial portion pale. Laterotergite, metepisternum and metepimeron light brown. Meron brown. Scutellum brown with ca. 10 elongate setae. Mediotergite dark brown with pale side margins. Legs ( Fig. 7D ) brown with ratio (n = 2): fore leg (10, 10.4, 8.8, 2.8, 1.8, 1, 1.2), mid leg (12, 11.6, 9, 2.8, 1.8, 1, 1.2) and hind leg (11.8, 12.8, 10.6, 3.4, 2.4, 1, 1.4). Mid and hind coxae paler than fore coxa; coxae with setae anterolaterally. Femora base pale. Fore and mid tibiae swollen apically; fore tibia with a patch of elongated setae on bulge. Hind tibia strongly swollen apically, bulge with a patch ca. 10–15 thickened setae, and a longitudinal cleft on inner portion; Tibiae with a simple apical spur, hind tibia spur twice than fore and mid tibiae. Claws pectinate with basal combs. Foretarsal and metatarsal claw: inner claw with one ventral tine, and outer claw with two ventral tines. Mesotarsal claw: inner and outer equals with one ventral tine, basal comb of inner claw smaller that outer claw. Wing ( Fig. 7E ) (n = 4; length: 2.75 mm; width: 1 mm) with membrane hyaline. Wing veins brown and setose. Weak light brown spot over crossvein r-m. Vein Sc ends basal to Rs origin. Vein R 2+3 curved, branched and with the origin near to crossvein r-m origin. Vein M 1+2 bifurcated, M bifurcation ends apical to R 2+3 branch origin. Crossvein m-m weak and near to the crossvein r-m terminus. False vein distinct and parallel to CuA, reaching ca. the basal 1/3 of CuA. Vein CuP ends apical to Rs origin. Length ratios R 2+3 /R 3, M 1+2 /M 2 = 0.50, and 1.85, respectively. Halter light brown. Abdomen uniformly light brown. Terminalia ( Fig. 8A ) uniformly brown. Tergite IX with pronounced convex posterior margin with scattered elongate setae, and slight and small convex area in the middle of posterior margin. Sternite IX with posterior margin with wide concave area, and lateral margin with ca. five elongate setae. Tergite X wider than long, anterior portion with two processes, latero-medial portion with a row of 6–7 short setae, and posterior portion with two pointed processes ( Fig. 8B ). Gonocoxite subcylindrical, wider than long, with gonocoxal apodeme elongated and its ventral portion with scattered setae. Apical gonocoxal lobe prominent, subtriangular, tapering in the apical portion, 0.7x length of gonostylus (in dorsal view), three elongate setae in basal to medial portion, and curved apex with 2–3 small apical setae; basal gonocoxal lobe absent. Gonostylus subtriangular (in lateral view), setose, dorsal portion with numerous stout setae, basal portion with 1–2 stout setae with tumescent base, subbasal portion with or without one stout seta, medial portion with 1–2 stout setae, subapical portion with 3–4 stout setae, and apical portion sharped with 3 stout setae. Paramere sinuous in dorsal view, anterior portion with two enlarged flaps that extend to the medial portion, and posterior portion tapered. Aedeagus with thin Y-shaped projection laterally, veil-like medial portion, and pointed projection originating from the lateral branch and reaching the posterior portion, nonetheless this structure is difficult to visualize.

Female. As for male, except: Body length: 3.0 mm (n = 2) Head: Antenna 0.65x length of wing. Flagellomere I 1.1X length of flagellomere II. Maxillary palpus ratio (I–IV): 1, 1.2, 2.4, 2.1. Thorax: Postpronotum with 2–5 setae. Legs: Ratio (n = 2): fore leg (10.2, 10.7, 9.7, 3.2, 2, 1, 1.2), mid leg (12.8, 13.2, 9, 4.5, 2, 1, 1.2), and hind leg (12.5, 12.8, 10.8, 4, 2.5, 1, 1.5). Claws simple. Wing ( Fig. 7F ) (n = 2; length: 2.85 mm; width: 1 mm): Vein M bifurcation similar level to R 2+3 branch. Crossvein r-m ends apical to crossvein m-m origin. Veins R 2+3 /R 3, M 1+2 /M 2 length ratios = 0.45, 1.05, respectively. Terminalia ( Fig. 9 ): Spermatheca rounded and light brown ( Fig. 9A ). Sternite VIII as long as wide and light brown, with posterior portion concave, wider than anterior portion, and setose. Tergite IX brown and setose. Sternite IX light brown, undivided piece, strip-shaped, with medial portion very narrow and lateral projection broad ( Fig. 9B ). Segment X brown, undivided, medial portion convex, setose and three pairs of elongated setae, with lateral projection reaching the base of the cercus. Cercus brown, subtriangular (in ventral view), setose, subtly longer than segment X, and basal portion directed to the inner portion ( Fig. 9C ).

Immatures. Unknown.

Distribution and bionomics. This species is known only from Brazil, Santa Catarina, Praia Grande, Parque Nacional de Aparados da Serra, Rio do Boi (type locality) ( Fig. 10 ). The specimens were collected with hand net near the river.

Remarks. Dixella spinosa is close to Dixella torrentia and Dixella moultoni ; the body color pattern of the three species is very similar, but the male terminalia are different: D. torrentia has a conical gonostylus without stout setae, Dixella moultoni has a cylindrical gonostylus with truncate apex ( Fig. 3D–E ), while Dixella spinosa has a triangular or subtriangular gonostylus with stout setae. The illustration of the terminalia of Dixella andeana ( Lane, 1942) presented in Lane (1953) resembles those of Dixella spinosa , but D. andeana has other distinctive characters, including four bristles at the apex of the apical gonocoxal lobe, wing with vein R 2+3 origin distal to crossvein r-m origin, and thorax (lateral view) yellow with two black stripes ( Lane, 1942). This new species has also a unique gonostylus among Neotropical species.

Etymology. The specific name is derived the latin adjective spinosus (= spiny), referring to the stout setae of gonostylus.

Figures

FIGURE 3. Dixella moultoni sp. nov., male terminalia: (A, D)—Dorsal view; (B)—Ventral view; (C)—Lateral view; (E)— Gonocoxite and gonostylus, dorsal view; (F)—Tergite X, dorsal view; (G)—Paramere, lateral view; (H)—Aedeagus, dorsal view. Scale bar: (A–C) 0.1 mm, (D, F) 0.05 mm, (E, G–H) 0.03 mm. Abbreviations: aed = aedeagus; ap lob = apical gonocoxal lobe; gon ap = gonocoxal apodeme; goncx = gonocoxite; gonst = gonostylus; par = paramere.

FIGURE 7. Dixella spinosa sp. nov. (A)—♂, Head, dorsal view; (B)—♂, Antenna; (C)—♂, Thorax, lateral view; (D)—♂, Legs, lateral view; (E)—♂, Wing; (F)—♀, Wing. Scale bar: (A, C) 0.2 mm, (B) 0.3 mm, (D) 1 mm, (E–F) 0.5 mm.

FIGURE 8. Dixella spinosa sp. nov., male terminalia: (A)—Dorsal view; (B)—Tergite X, dorsal view. Scale bar: (A) 0.05 mm, (B) 0.03 mm Abbreviations: aed = aedeagus; ap lob = apical gonocoxal lobe; gon ap = gonocoxal apodeme; goncx = gonocoxite; gonst = gonostylus; par = paramere.

FIGURE 9. Dixella spinosa sp. nov., female terminalia: (A)—Ventral view; (B)—Sternite IX; (C)—Cercus and segment X, ventral view. Scale bar: (A) 0.1 mm, (B–C) 0.04 mm. Abbreviations: cer = cercus; seg X = segment X.

FIGURE 10. Distribution map of Dixella species in Santa Catarina state, Brazil.