Margdalops, Jindr & Rohác & ek & Barraclough, 2003

Jindr, Rohác, ich, ek & Barraclough, David, 2003, Margdalops, a new African genus of Anthomyzidae (Diptera), comprising six new species, African Invertebrates 44 (2), pp. 1-35 : 3-5

Margdalops gen. n.

Type species: Margdalops venustus sp. n., by present designation.

Etymology: The name is an abbreviated conjunction of ‘ Marg [o + Amyg] dalops ’ and is derived from dark brown margin of the wing (margo = Lat. margin). Gender masculine.

Description:

(1) Head ( Figs 42, 48 ): As long as or slightly longer than high. (2) Eye large, convex, ovoid, with longest diameter oblique. (3) Occiput strongly concave. (4) Occiput (and often also frons) with a pair of medial silvery white microtomentose stripes. (5) Frons very narrow; frontal triangle long, narrow and microtomentose (only ocellar triangle bare, shining). (6) Frontal lunule small but distinct. (7) Antenna geniculate between pedicel and 1st flagellomere; pedicel overlapping base of 1st flagellomere. (8) Arista long ciliate, never pectinate ( Figs 42, 48 ). (9) Palpus slender, with 1 distinct subapical seta. Cephalic chaetotaxy: (10) pvt short but crossed or strongly convergent; (11) vte longest of cephalic setae (vti, oc, and posterior ors often of same length); (12) vti as long as or slightly shorter than vte; (13) 2 long ors, the posterior in the middle of orbit, the anterior close to fore margin of frons, plus 2 microsetulae just in front of anterior ors; (14) a single row of minute postocular setulae; (15) 1 long vi and 1–2 shorter subvibrissae; (16) peristomal setulae few in number, about twice as long as postoculars. (17) Thorax ( Fig. 42 ): Distinctly narrower than head. (18) Pleura with dark, longitudinal band at dorsal margin or entirely brown. Thoracic chaetotaxy: (19) 1 hu, 2 npl (anterior longer); (20) 1 short sa, 1 longer pa; (21) 1 distinct prs, longer than in Amygdalops ; (22) 2 postsutural dc, the anterior long and inserted in the middle between suture and posterior dc; (23) ac microsetae in 4 rows in front of suture, in 2 rows or absent behind anterior dc; (24) 2 sc, the apical long, the laterobasal small; (25) 1 minute ppl; (26) 2 stpl, the anterior shorter and weaker. Legs: (27) Fore leg always unicolorous, yellow; (28) f 1 without ctenidial spine; (29) t 2 with distinct ventroapical seta; (30) male (rarely also female) f 3 with posteroventral row of setae, with those in apical third shortened and thickened ( Fig. 65 ). (31) Wing ( Figs 66–71 ) long and very narrow; (32) wing membrane with dark brown band along anterior margin; (33) C without thick spinulae; (34) R 2+3 long, sinuate, close to C and ending more than twice further from apex of R 4+5 than M; (35) R 4+5 slightly sinuate to almost straight; (36) R 4+5 and M slightly to distinctly convergent apically; (37) M straight or very slightly bent; (38) discal (dm) cell short and very narrow, with cross-vein r-m situated near or anterior to its middle; (39) CuA 1 relatively long, almost reaching wing margin; (40) A 1 and anal lobe reduced, anal (cup) cell very narrow; (41) alula small and very narrow, dark brown.

Male abdomen: (42) T1 separate from T2, at least dorsally; (43) T2–T5 large and broad, uniformly dark brown. (44) S1–S5 much narrower, at most slightly paler than terga. Male postabdomen: (45) T6 small, transverse, weakly sclerotised; (46) S6-S8 fused dorsolaterally; (47) S6 strongly asymmetrical and its ventral part very shortened; (48) S7 asymmetrical, placed laterally; (49) S8 relatively long, less asymmetrical and situated dorsally.

Male genitalia ( Figs 13–18 , 36–41 ): (50) Epandrium moderately to very broad; setosity variable, usually dorsomedial (often also ventrocaudal) seta longest. (51) Medandrium usually wide and medially shortened (low); (52) cercus heavily sclerotised and usually enlarged. (53) Gonostylus variable, with longest setae in anterior half of inner side, micropubescence on outer side usually developed. (54) Hypandrium simple, with internal lobes reduced; (55) transandrium ( Fig. 15 ) simple, without caudal process, only lateral sides of basal membrane weakly sclerotised. (56) Pregonite fused to hypandrium and incurved, at most with small tubercle in posterior part ( Figs 16 , 41 ), with 2 groups of setae. (57) Postgonite simple and slender, more or less flattened; sometimes with small basal sclerite attached to its proximal part ( Fig. 3 ). (58) Aedeagal part of folding apparatus ( Fig. 39 ) dorsally membranous, laterally provided with lenticular tubercles or spines; its outer wall (attached to postgonite) striated; (59) connecting sclerite ( Figs 2 , 39 ) pale to dark pigmented. (60) Basal membrane medially with small transverse tubercles or spinulae, laterally weakly sclerotised. (61) Phallapodeme with distinctly (sometimes asymmetrically) bifurcate base. (62) Aedeagus with short, frame-like phallophore and (63) distiphallus composed of voluminous membranous saccus and slender sclerotised filum. (64) Saccus reinforced by a pair of basal sclerites and its membrane armed by various spines, setae or tubercles; (65) filum formed by 2 dark, slender band-like sclerites, in more advanced taxa largely fused and with various teeth and processes. (66) Ejacapodeme small to medium-sized, with slender digitiform projection.

(67) Female abdomen: With broader terga (T2–T6) and narrower sterna (S2–S5). (68) Postabdomen ( Figs 43, 47 ) relatively short, broad and well sclerotised; (69) T6 and S6 relatively large. (70) T7 laterally somewhat extended, rarely reaching ventral side and enclosing spiracles; (71) S7 slightly modified, usually simple, dark pigmented; (72) T8 plate-shaped, transverse, with rounded posterior corners; (73) S8 small, slightly protruding posteromedially, with a narrow, posteromedial incision. (74) Internal sclerotisation of genital chamber (uterus) well developed ( Figs 44, 46 ), formed by 1–3 pairs of posterior crooked sclerites and (75) 1 ventral ring-shaped sclerite being twisted and tenuous in some specimens. (76)Anterior part of uterus with membranous or weakly sclerotised cup-like to flask-shaped ventral receptacle ( Figs 22 , 46 ) with a digitiform or vermicular terminal projection. (77) Accessory gland of usual form, on subterminally dilated and ringed duct. (78) Spermathecae (1+1) spherical or nearly so ( Figs 32 , 45 ), with distinct cervix, and body surface near duct insertion carrying very small tubercles or spinulae with stalked microglobules. (79) T10 small, at least partly dark, with 1 pair of dorsal setae and some micropubescence; (80) S10 usually wider and longer than T10, simple, densely micropubescent and with posterior row of setulae. (81) Cercus short and broad, with short but profuse setae.

Discussion: Margdalops gen.n. is best diagnosed by the combination of the character states 2–4, 6, 8, 12, 13, 18, 21, 22, 28, 30, 32, 38–41, 51, 52, 54–56, 58, 60, 70, 71, 73, 76, 78 and 81. However, some of these features are shared synapomorphies with the genus Amygdalops Lamb, 1914 , demonstrating the sister-group relationships of these two genera, viz. 2, 3, 5, 13, 18, 28, 30, 40, 41, 73, 76 and 81. Margdalops differs from Amygdalops in a number of features, both plesiomorphic with respect to those in Amygdalops (e.g. 6 – frontal lunule distinct, 8 - arista ciliate, 12 – vti long, 21 – prs distinct, 39 - CuA 1 long, 55 – transandrium without medial caudal process, 58 - aedeagal folding apparatus dorsally membranous, 71 – female S7 slightly or unmodified, also 54, 56, 60, 70, 78) and autapomorphic (4 – occiput with a pair of silvery microtomentose stripes, 22 – dc inserted more anteriorly, 32 - wing darkened along anterior margin, 38 – dm cell shorter and very narrow, 51 – medandrium wide and medially shortened, 52 - male cercus strongly sclerotised). These apomorphic features confirm the monophyly of the new genus. Consequently, species of Margdalops can be distinguished from all other Anthomyzidae in having an Amygdalops -like head with silvery white stripes (at least on occiput), a long ciliate (not pectinate) arista, anteriorly located dc macrosetae, a dark margined wing and a heavily sclerotised male cercus.

At present the genus is known only from Africa. The six new species described below probably represent only a small part of existing species diversity. This is suggested by 3 additional unnamed species (one each from Nigeria, Kenya and Tanzania) which remain undescribed due to insufficient available material. The species are treated below following the systematic order based on the presumed relationships.

Figures

Figs 42–48. Margdalops venustus sp. n., male and female paratypes (S. Africa). 42. Male head and thorax, dorsal view. 43. Female postabdomen, dorsal view. 44. Female internal sclerites, ventral view. 45. Spermathecae. 46. Female genital chamber with internal sclerites, lateral view. 47. Female postabdomen, ventral view. 48. Male head, lateral view. Scales: Figs 42, 48 = 0.2 mm, others = 0.1 mm. For abbreviations see text.

Figs 61–65. Margdalops caligatus sp. n., female paratype (Kenya). 61. Spermathecae. 62. Genital chamber with internal sclerites + 8th abdominal segment, lateral view. 63. Female postabdomen, dorsal view. 64. Same, ventral view. 65. f3, posterior view. Scales: Figs 61, 62 = 0.1 mm, others = 0.2 mm. For abbreviations see text.

Figs 66–68. Wings of Margdalops species. 66. M. microcercus sp. n., female paratype (Kenya). 67. M. angustus sp. n., female pararype (S. Africa). 68. M. signatus sp. n., female paratype (Kenya). Scale = 0.5 mm.

Figs 69–71. Wings of Margdalops species. 69. M. venustus sp. n., male paratype (S. Africa), 70. M. bifilum sp. n., male paratype (Kenya), 71. M. caligatus sp. n., male paratype (Kenya). Scale = 0.5 mm.

Figs 13–18. Margdalops angustus sp. n., male holotype (S. Africa). 13. External genitalia, caudal view. 14. Same, lateral view. 15. Transandrium, caudal view. 16. Hypandrium and associated structures, lateral view. 17. Aedeagal complex, lateral view. 18. Gonostylus, sublateral view (widest extension). Scales: Fig. 18 = 0.05 mm, others = 0.1 mm. For abbreviations see text.

Figs 36–41. Margdalops venustus sp. n., male paratype (S. Africa). 36. External genitalia, caudal view. 37. Same, lateral view. 38. Transandrium, caudal view. 39. Aedeagal complex, lateral view. 40. Gonostylus, sublateral view (widest extension). 41. Hypandrium and associated structures, lateral view. Scales: Fig. 40 = 0.05 mm, others = 0.1 mm. For abbreviations see text.

Figs 1–6. Margdalops microcercus sp. n., male holotype (Kenya). 1. Transandrium, caudal view. 2. Aedeagal complex, lateral view. 3. Hypandrium and associated structures, lateral view. 4. External genitalia, caudal view. 5. Same, lateral view. 6. Gonostylus, sublateral view (widest extension). Scales: Fig. 6 = 0.05 mm, others = 0.1 mm. For abbreviations see text.

Figs 19–23. Margdalops angustus sp. n., female paratype (S. Africa). 19. Postabdomen, dorsal view. 20. Spermatheca. 21. Internal sclerites, ventral view. 22. Genital chamber with internal sclerites, lateral view. 23. Postabdomen, ventral view. Scales: Figs 19, 23 = 0.1 mm, others = 0.05 mm. For abbreviations see text.

Figs 30–35. Margdalops signatus sp. n., female paratype (Kenya). 30. Postabdomen, dorsal view. 31. Same, ventral view. 32. Spermatheca. 33. Internal sclerites, ventral view. 34. Genital chamber with internal sclerites, lateral view. 35. Spermatheca. Scales: Figs 30, 31 = 0.1 mm, others 0.05 mm. For abbreviations see text.