Mythenteles rameli Gibbs

Gibbs, David, 2009, A new microbombyliid Mythenteles rameli sp. n. (Diptera, Mythicomyiidae) from Northern Greece, Zootaxa 2162, pp. 50-56 : 51-56

Mythenteles rameli Gibbs , sp. n.

Description. Wing Length: 1.2–2 mm. Male ( Fig. 1). Head. Black; eyes dichoptic, most widely separated at vertex, narrowing slightly to antennal bases. Ocellar tubercle a shade browner than the occiput with a scattering of short brown hairs, frons between front ocellus and antennae yellow, depressed medially with small dark spot in middle of hollow ( Fig. 3). Ocelli disposed in an obtuse triangle, the lateral ocelli separated from the eye margin by approximately the diameter of that ocellus. Face, mouth margin and venter of head adjacent to oral opening yellow, merging through brown into black occiput, face about twice as high as wide. Viewed laterally lower part of face slightly protuberant so visible beyond curve of eye, with a few short, pale hairs. Antennae dark brown, tending to become blacker apically; first flagellomere most similar to M. coptopheles Evenhuis ; style relatively longer, more like M. deemingi Evenhuis , with apical sensillum relatively long ( Fig. 2 ). Occiput lightly dusted but still shining black with a covering of short blackish hairs. Proboscis pale brown, short and robust, in most specimens produced beyond oral margin but not exceeding tip of antennae, labrum shorter than longest diameter of eye, sclerotized basally, apically transparent and bluntended; palpus vestigial, narrow-conical with white apical bristle or two.

Thorax. ( Fig. 3) Mesonotum medially subshining black, lightly dusted, anteriorly between dorsocentral lines the dark colour continues to the pronotum. Pronotum, post pronotal lobe, triangular area between dorsocentral line and post pronotal lobe, notopleuron, a medially constricted stripe from thoracic suture to post alar callus and post alar callus yellow. Disc of mesonotum with a scattering of short, dark brown hairs, rather randomly distributed but an irregular acrostical line is apparent, anteriorly reclinate, posteriorly proclinate. Yellow part of mesonotum with scattered yellow hairs, area just in front of and above wing base with a line of three longer, brown bristles. Scutellum subshining, varying from mostly yellow with narrow black line basally to mostly dark with apical yellow spot; with scattered pale hairs about as long as those on mesonotum. Pleura mostly yellow, anepisternum with black anteroventral spot which extends along anterior margin curving posteriorly to form an inverted comma-shape. Anepimeron, brown for ventral third and irregularly along anterior margin, katepisternum blackish on ventral two thirds, meron mostly dark brown, yellow along anterior and dorsal margins. All sclerites lightly dusted, subshining, posterior part of anepisternum with short yellow hairs.

Legs. Coxae yellow, the fore coxae (and to a lesser extent the mid and hind coxae) variably dark brown basally. Trochanters yellow, femora brown with base narrowly paler, fore femora yellow for apical third, mid and hind femora yellow for apical quarter to a fifth. Tibia yellow, basitarsus yellow, remaining tarsal segments progressively darker brown to black.

Wing. ( Fig. 4 ). Hyaline; veins pale brown; costa ends slightly more than one-third way between end of R4+5 and M1. Vein Sc incomplete, ending at about two fifths the way between origin of Rs and end of vein R2+3. Rs connected to R1 by almost straight R2+3. R4+5 gently curved posteriorly until close to wing margin where curves slightly anteriorly. Vein M1 relatively abruptly curved basally then straight for apical three quarters. M2 almost straight to wing margin; cell dm closed by crossvein DM-Cu which joins M1+2 just before confluence of M1 and M2 or M2 just after the confluence. Crossvein DM-Cu oblique, curved close to vein Cu so joining it approximately at right angles, crossvein otherwise straight. CuA1 well developed to wing margin; A1 straight basally, undulating for apical half. Fringe of hair on posterior margin of wing typical. Halter . Stem pale yellow, knob whitish yellow.

Abdomen. Tergites mid to pale brown, with scattered brownish hairs a little longer than the distance between them. Tergites I with a narrow, yellow basal band and an even narrower yellow apical margin.

Tergites II–VII with successively broader yellow apical margins that widen laterally to occupy most of length of respective tergite. Sternites similar but with wider yellow apical bands, especially basal sternites which can be mostly pale yellow. Genitalia. Mostly yellow, gonocoxite basally brown, epandrium obscurely darker basally, apical extensions of epandrium browner. Dissected genitalia Figs 5–10 .

Female. Very similar to male, eyes slightly more widely separated, particularly the face below antennae with width to height ratio approximately 1:1.5 (1: 2 in male) but this is variable, some almost as male. There is a tendency for the yellow areas to be more extensive in females but there is greater individual variability than the average difference between the sexes. Female genitalia ( Fig. 11 ) not really like any other species for which illustrations are available, perhaps closest to M. propleuralis (Melander) from the USA. The furca is similar to M. propleuralis with bifurcate basal parts but differs from all other Mythenteles thus far illustrated in having elongated spemathecal reservoirs. All spermathecae seem to be functional, as usual the middle one is shorter then the lateral ones. In the few specimens dissected the lateral spermathecae appear to be asymmetrical, viewed ventrally the right spemathcal duct appears to be longer than the left. However, these structures are so delicate that it proved impossible to stretch them out without damage to confirm this. The apical sternite ( Fig. 12 ) is likely to be useful for specific diagnosis but this sclerite is not illustrated for other species.

Types. Holotype GREECE, Serron, Wetland Kerkini, Kerkinis Mts above Neo Petritsi, 750m E23°16' 35.6ʺ N41°18' 49.8ʺ 16–22 June 2008, Malaise trap, leg. G. Ramel [3]. Paratypes GREECE, Serron, Wetland Kerkini, Kerkinis Mts above Neo Petritsi, 750m E23°16' 35.6ʺ N41°18' 49.8ʺ 16–22 June 2008, Malaise trap, leg. G. Ramel [22327Ƥ]; 23–29 June 2008 [17327Ƥ(plus 63 in alcohol)]; 30 June–6 July 2008 [231Ƥ].

Type depositories. Holotype in National Museum of Wales Cardiff ( NMWC); Paratypes in NMWC [5310Ƥ]; Bishop Museum, Honolulu [535Ƥ]; Oxford University Museum [535Ƥ]; Natural History Museum, London [113(includes 63 in alcohol) 5Ƥ]; Muséum National d'Histoire Naturelle, Paris [232Ƥ]; collection of Wetland Kerkini, Greece [535Ƥ]; remainder in private collection D.J. Gibbs.

Etymology. The specific epithet is in honour of Gordon J.L. Ramel of the Management Authority of Wetland Kerkini in recognition of the enormous work he put into Project Kerkini.

Habitat and Distribution. Although Project Kerkini ran traps at more than 20 sites between 2004 and 2008, all examples of M. rameli come from a single site between 16 June and 6 July 2008. The trapping site differed from most others on this project being situated on a dry, sunny, south-facing slope within a mixed deciduous forest dominated by Acer campestris, Ostrya carpinifolia and Quercus robur . The trap was sited on an abandoned, cleared track (5 metres wide on average) with an adjacent rich herbaceous plant community dominated by Marrubium perigrinum . Other plants recorded from the area include Cichorium intybus, Echium italicum, Hypericum montbretii, Hypericum perforatum, Lithospermum purpurocaerulea, Salvia sclarea, Teucrium chamaedrys, Convolvulus sp., Euphorbia sp., Onopordum sp., Thymus sp., Trifolium sp., Verbascum sp. and the grasses Bromus sp., Koeleria sp. (Gordon Ramel pers. comm.).

Since discovering M. rameli , no further specimens from elsewhere have come to light, so at the moment it is known only from the type locality. It is very likely that this species will occur more widely in northern Greece and adjacent Bulgaria. However, extrapolating from what little is known about the distributions of other Mythenteles , M. rameli is unlikely to be very widely distributed and probably will not be found beyond the Balkans.

Discussion. Mythenteles rameli does not seem to be closely related to any described species. Externally it is perhaps most similar to M. wadimurri Evenhuis & Theodor from Israel, resembling it in the extent of yellow colour, although M. wadimurri is significantly more yellow and lacks crossvein DM-Cu. However, the female genitalia are very different and do not suggest a close relationship. The male genitalia of Mythenteles so far examined are so diverse that no relationships can be readily discerned, and this is certainly the case in M. rameli . The female genitalia are more enlightening, M. rameli showing the closest similarity with M. propleuralis and M. silus Evenhuis from the west coast of America, the former with the most similar furca, the latter with similar spemathecal ducts. Of the species where the genitalia have not yet been examined, based on external similarities, the most likely close congener is M. asiatica .

Figures

FIGURE 2. Antennae Mythenteles rameli sp. n.

FIGURE 4. Mythenteles rameli sp. n. wing.

FIGURES 5 – 12. Mythenteles rameli sp. n. male and female genitalia. 5. epiphallic complex, ventral view, 6. epiphallic complex, lateral view, 7. gonocoxite, ventral view, 8. gonocoxite, lateral view, 9. epandrium, dorsal view, 10. epandrium, lateral, 11. female genitalia, 12. female last stenite.