Curtonotum transitus Lindsay, 2019

Lindsay, Kate G., Klymko, John & Marshall, Stephen A., 2019, Revision of the Central American and Mexican species of the Curtonotum murinum species complex (Diptera: Curtonotidae), Zootaxa 4651 (3), pp. 531-554 : 550

Curtonotum transitus Lindsay , sp. nov.

Figures 40–46

Differential diagnosis. Distinguished from its congeners by the inner lobe of the surstylus which is 7–8 times as long as wide and wedge shaped and the distiphallus, which has a distal leaf-like lobe that is elongate, sclerotized and folded on the left side with microtrichia on either side. The upper projection is curled, thin and tapered and the lower projection is membranous and folded ( Fig. 46 ). Tergite 3 has a posterior band covering 1/10 to 1/8 of the tergal length ( Fig. 42 ). Females are here treated as indistinguishable.

Description. Male: Overall length (excluding wings): 5.1–5.3 mm.

Head: Vibrissa subequal to subvibrissal setae. Parafacial thin, gena approximately 1/4 width of postpedicel. Postpedicel 1.5–2 times length of pedicel. Arista with 6–8 dorsal branches, 4–6 ventral branches. Thorax: Scutum with faint grey dorsal markings. Postpronotal lobe with 3 setae (1 long, 2 shorter subequal) and sometimes several thin, poorly defined setulae ventrally. Line of setulae above fore coxa black.

Legs: Orange to beige, hind femur with wide, dark brown preapical band.

Wing: Light grey-brown, with indistinct infuscation around crossvein dm–m and along anterior margin.

Abdomen: Tergite 2 with 2 posterolateral markings covering almost 1/3 of tergite. Tergites 3–5 with dark median vitta and thin, mottled, lateral triangles. Band on posterior margin of tergites 3–5 adjoining the medial and lateral markings very thin, covering approximately 1/10 to 1/8 length of tergite 3.

Male terminalia: Cercus somewhat elongate, same length as epandrium at widest point. Surstylus thin and straight, modified into 2 lobes, inner lobe same length as cercus and black, wider proximally, 7–8 times as long as wide. Outer lobe 2 times width of inner lobe. Postgonite harpoon shaped. Hypandrium with blunt dorsobasal projection. Phallapodeme thin, shorter than epandrium. Distiphallus with elongate distal leaf-like lobe slightly folded inwards on left with microtrichia on both edges and sclerotization on left side. Upper projection strongly recurved lower projection folded and membranous.

Female: Unknown.

Etymology. From the Latin, transitus , meaning “transition”, which refers to the notion that this species shares a combination of morphological traits with two other species in the C. murinum species complex ( C. irksum sp. nov. and C. prolixum sp. nov.).

Comment. Three females matching the general external diagnosis of C. transitus sp. nov. from Mexico were dissected, but no distinct terminalia characters could be identified to diagnose females of the species.

Type material. Holotype and one paratype: ♂: MEXICO. Saint Luis Potosi: El Salto, El Naranjo, [22°27’3.286”N, 99°20’24.506”W], 29.VI.1965, P.J. Spangler . Other paratype: BELIZE. Stann Creek District: ♂, Cockscomb Basin Wildlife Sanctuary , 16°47’N, 88°30’W, 5–6.IV.1993, W.N. Mathis (all USNM).

Other material examined. COSTA RICA. Guanacaste: # F, R.V.S. Bosque Diria, Estacion Diria, 100–200 m, 9.II.2003, W. Porras, L_N_239550_361650#72366; #M, Santa Cruz, Camino a la Esperanza, 420 m. 21.V.2001, B. Hernandez, L_N_238450_363050#54073; Limon: ♀, R.V.S. Gandoca-Manzanillo, Punat Mona, 0–3 m, 6.XI.2001, B. Hernandez, L_S_395700_614500#69061 ( MNCR) . MEXICO. Jalisco: ♀, Chamela , 26-30.IX.1985, F.D. Parker, T.L. Griswold; ♀, Chamela, 1-8.X.1985, F.D. Parker, T.L. Griswold. Guerrero: ♀, Zihuatanejo, 12.XII.1966, G.E. Bohart ( UTAH) . COSTA RICA

Figures

FIGURES 40–42. External characters of Curtonotum transitus sp. nov.. 40. Habitus, lateral view ♂. 41. Head, anterior view. 42. Abdomen, dorsal view.

FIGURES 43–46. Curtonotum transitus sp. nov.. 43. Male terminalia, left lateral view. 44. Same, posteroventral. 45. Same, external left lateral view. 46. Detail of distiphallus, dorsal view.