Amygdalops trivittatus Frey, 1958

Jindr, Rohác, ich & ek, 2004, Revision of the genus Amygdalops Lamb, 1914 (Diptera: Anthomyzidae) of the Afrotropical Region, African Invertebrates 45, pp. 157-221 : 165-167

Amygdalops trivittatus Frey, 1958

( Figs 21–25 , 122 )

Amygdalops trivittata Frey, 1958: 32 [description].

Amygdalops trivittatus: Sabrosky 1980: 650 [Afrotropical catalog]; Rohác˘ek 1998 a: 172 [world checklist]. Type material: Holotype female, labelled: ‘Ins. Cabo Verde, S. Antão Pombas, 23– 26.12.1953, Lindberg’, ‘Holotypus’ (in black frame on red label), ‘Holotypus’ (red) and ‘ Amygdalops trivittatus Frey, J. Rohác ˘ek des. 2002, ^ Holotypus’ (red) (MZHF, genit. prep.).

Description: Male unknown. Female. Total body length 1.67 mm. Body bicolorous, yellow and brown. Head distinctly higher than long. Occiput completely brown. Frons brown except brightly yellow anterior fourth. Frontal triangle relatively broad and with rounded anterior corner, entirely brown and including ocellar triangle shiny. Orbit brown and shiny in posterior two-thirds, yellow and dull anteriorly. Stripes between orbits and frontal triangle densely golden yellow microtomentose. Face, parafacialia (= narrow listel between face and eye), gena and postgena white; parafacialia and gena silvery white microtomentose; mouthparts including palpus whitish yellow. Cephalic chaetotaxy incompletely recognisable, because some setae missing: pvt small but crossed; vti about as long as anterior ors; vte and posterior ors lost but probably strongest of cephalic setae; oc about as long as vti; 2 long ors (the posterior broken off, the anterior relatively short and weak) and only 1 microsetula in front of anterior ors recognised; no microsetae visible medially in front of frontal triangle; 1 long vi and 1 also long subvibrissa (about three-fourths of vi); peristomal setulae few, twice as long as postocular setulae. Eye less oblique than in other congeners; its longest diameter 1.4 times as long as shortest one. Gena narrow, its smallest height 0.1 times as long as shortest eye diameter.Antenna pale yellow but darker around base of arista. Arista 1.9 times as long as antenna, long pectinate.

Thorax slightly narrower than head, bicolorous. Mesonotum with wide medial dark brown band between dorsocentral lines, somewhat widened anteriorly and covering whole scutellum; consequently humeral and notopleural yellow band extended on lateral parts of scutum. Pleura with pale brown band wider posteriorly, strongly tapered anteriorly, covering only vicinity of anterior (mesothoracic) spiracle and with enlarged yellow to whitish yellow ventral part. Thoracic chaetotaxy: 1 hu, 2 npl (anterior almost twice as long as posterior); 1 very small prs; 1 short sa; probably 1 pa (broken off); 2 dc but anterior reduced to small setula, posterior as long as apical sc; 2 sc, apical long, laterobasal very short and weak, hair-like; ppl not visible; probably 2 stpl but only posterior preserved (on holotype), long but fine; other sternopleurals few and fine. Legs yellow to yellowish white. f 1 with few setae in posteroventral row; ventroapical seta on t 2 short but distinct; f 3 without specialised setae, simply setulose. Wing ( Fig. 122 ) relatively short and broad, without dark pattern, membrane uniformly yellowish white. R 4+5 and M almost parallel in apical third of wing. A 1 and particularly CuA 1 strikingly longer than in all congeners although not reaching wing margin. Anal lobe well developed. Wing measurements: length 1.77 mm; width 0.62 mm, Cs 3: Cs 4 = 1.70, r-m\dm-cu: dm-cu = 3.11. Haltere yellow.

Abdomen. Preabdominal T1–T2 brown, T3–T5 (and also T6) brown with large pale yellow laterobasal spot on each side, that on T4–T6 extended behind middle of tergum ( Fig. 21 ); preabdominal sterna pale yellow, narrow, becoming wider posteriorly, from S4 being distinctly wider than long.

Postabdomen ( Figs 21, 24 ) short and wide. T6 narrower than T5 but with the same pale laterobasal spots. S6 distinctly wider and more transverse than S5, pale yellow to ochreous. T7 narrow, with shallow anterior emargination and dense short and thick setae. S7 very distinctive, heavily sclerotised, dilated anteriorly with strongly expanded anterolateral corners and with a pair of darker longitudinal bands. T8 paler pigmented than T7, plate-shaped, somewhat expanded anteromedially and more or less rounded posteriorly. S8 very narrow (only slightly wider than S10), posteromedially bulging and bent dorsally, and with usual narrow posteromedial incision. T10 short pentagonal, with indistinct unpigmented posteromedial margin, with a pair of longer setae in front of the latter but completely without microtomentum. S10 slightly larger than T10, finely setulose at posterior margin. Internal sclerotisation of genital chamber complex ( Fig. 23 ), distinctly developed though pale pigmented, composed of anterior cordate ring-shaped sclerite and of two pairs of posterior bent sclerites connected with S8. Ventral receptacle ( Fig. 22 ) represented by short, membranous, very slightly clavate tube, with apical ventrally bent digitiform process. Spermathecae ( Fig. 25 ) 2+1 [the paired spermathecae are probably a monstrosity due to secondary splitting of single spermatheca during ontogenesis], all spherical, with few blunt spines or processes on surface of basal half, and with comparatively long sclerotised cervix. Cerci small, comparatively short, with moderately long setosity.

Discussion: A. trivittatus Frey, 1958 is an easily recognisable species; it differs from all congeners in the area under study by the unspotted wings, distinctive colour pattern of thorax and the uniquely formed female S7 (see key). Despite the limited set of characters for phylogenetic consideration (because only the female is known) it is apparent that this species accumulates a number of plesiomorphic features which are unknown in other species of the genus, eg. head higher than long, eye slightly oblique, unicolorous wing membrane, relatively broad wing, well developed anal lobe, and long veins A 1 and CuA 1. For this reason A. trivittatus is considered a primitive species closest to the ancestor of the genus which represents the sister-group to all other Amygdalops species in the Afrotropical Region (cf. Fig. 133 ).

Biology: Unknown.

Distribution: The species is known only from the female holotype from Santo Antão I. in the Cape Verde archipelago.

Figures

Figs 21–25. Amygdalops trivittatus Frey, female holotype. 21. Postabdomen + 5th segment, dorsal view. 22. Ventral receptacle, lateral view. 23. Genital chamber with internal sclerites and S8, ventral view. 24. Postabdomen + 5th segment, ventral view. 25. Spermathecae. Scales: Figs 21, 24 = 0.1 mm, others = 0.1 mm. For abbreviations see text.

Figs 122–125. Wings of Amygdalops species. 122. A. trivittatus Frey, female holotype. 123. A. thomasseti Lamb, male (Uganda). 124. A. obtusus sp.n., male paratype (Kenya). 125. A. simplicior sp.n., male paratype (Nigeria). Scales = 0.5 mm.

Fig. 133. Cladogram showing the inferred relationships of the Afrotropical species of Amygdalops. Characters mentioned in the cladogram (apomorphic state - A, plesiomorphic - P):