Drosophila caxarumi , Penafiel-Vinueza, Ana Danitza & Rafael, Violeta, 2018
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Drosophila caxarumi sp. n. Figs 6 A–B, 7 A–E, 8 A–F
Holotype ♂ (dissected, terminalia in microvial), Ecuador, Loja, Cajanuma, 2675 m, 4°6'53.7"S; 79°10'54.6"W, 19 Nov. 2015, A. Peñafiel col., A. Peñafiel & V. Rafael det. ( QCAZ-I 3306).
2 ♂♂ (dissected, terminalia in microvial), Ecuador, Napo, Río Guango, 2548 m, 00°32'14.0"S; 77°57'13.4"W, 19 Sep. 2015, A. B. Manzano col., A. Peñafiel & V. Rafael det. ( QCAZ-I 3307-3308).
Body color yellow. Aristae with four dorsal and two ventral branches. Two prominent oral bristles. Thorax brown. Clear wings. Aedeagus with two dorsal membranes covered in microprojections which continue to a sclerotized triangular projection and another distally serrated sheet joined ventrally by a membrane. Hypandrium in shield-shape. Gonopod fused to paraphyses, bearing a long bristle and short bristle.
Male. Holotype external morphology: total length (body + wings) 2.90 mm, body length 2.30 mm. Body color brown.
Head. Aristae with four dorsal and two ventral branches plus terminal fork and small hairs. Orbital plate yellowish brown; frontal length 0.25 mm, frontal index = 1.0; top to bottom width ratio = 1.68. Medial vertical seta closer to lateral vertical seta and slightly towards the outer edge of the orbital plate. Distance of or3 to or1 = 0.06, distance of or3 to vtm = 0.09, or1-or3 ratio = 0.59; or2-or1 ratio = 0.30. Ocelar triangle yellow, distance of postocellar setae = 0.52 of frontal length, ocellus yellow; frontal vitta yellow. Two prominent oral bristles, vibrissa index = 0.85. Cheek index = 3.33. Carina not sulcate. Eyes wine red, eye index = 1.30.
Thorax. Brown (Figure 6A), thorax length 0.66 mm. h index = 1.18. Transverse distance of dorsocentral setae = 1.53, dc index = 0.81. Distance between apical scutellar seta = 1.38, scut index = 0.93, sterno index could not be calculated (broken bristles in holotype). Clear wings. Alar length 1.65 mm, alar width 0.86 mm. Alar indices: alar index = 1.91; C = 3.37; ac = 1.94; hb = 0.25; 4c = 0.89; 4v = 2.25; 5x = 1.44; M = 0.66 and prox. x = 0.46.
Abdomen. Yellow, 1st - 6th tergites with dark brown pigmentation that covers entirely each tergite (Figure 6A).
Male terminalia. Epandrium microtrichose with four lower and no upper bristles, one bristle on the ventral lobe. Cerci not fused to epandrium, microtrichose, tip bearing four cotton swab-shaped bristles. Surstylus rectangular with seven primary teeth, six secondary sharp teeth on the right and five on the left, six marginal bristles (Figs 7A, 8A). Hypandrium in shield-shape and sclerotized. Gonopod elongated, fused to the paraphyses, bearing a long bristle and other short one (Figs 7B, 8B).
Aedeagus. Sclerotized, with two dorsal membranes covered in microprojections which continue to a sclerotized triangular projection and another distally serrated sheet joined ventrally by a slightly sclerotized membrane (Figs 7 C–E, 8C).
Variation in paratypes (dry mounted specimen). Cannot be calculated, broken bristles in paratypes.
Drosophila caxarumi is known from two localities (elevation range is 2548-2675 m) from Loja Province, Podocarpus National Park and Napo Province, Río Guango.
Unknown. The type specimen was found in the fermented banana-bait traps placed at the locality, which suggests that this species feeds or breeds on fermented fruit as many other Drosophila species. The habitat is a well-preserved intermediate montane forest.
Relationship to other species.
The most similar species to Drosophila caxarumi sp. n. is D. guaraja King, 1947b. We compared D. caxarumi with descendants of D. guaraja reared from an isofemale line named ZBCI036 from Podocarpus National Park, Bombuscaro, 1000 msnm. These two species share the same cotton swab-shaped bristles on the ventral side of the cerci (Figure 8A, D). Drosophila caxarumi and D. guaraja differ in the general shape of the aedeagus (Figure 8C, F). In D. caxarumi the aedeagus is bent towards the dorsal side. In D. guaraja the paraphyses are microtrichose while in D. caxarumi they are smooth and hairless. Both species differ markedly in external morphology (Figure 6A, B), body color of D. caxarumi is mainly brown while in D. guaraja is yellow. D. guaraja abdomen is yellow with broad, dark brown bands different from the brown abdomen in D. caxarumi (Figure 6A, B).
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