Moegistorhynchus turneri Barraclough & Colville, 2024

Barraclough, David A. & Colville, Jonathan F., 2024, Revision of the endemic South African genus Moegistorhynchus Macquart (Diptera: Nemestrinidae), with a species key, description of three new species and comments on pollination biology and biogeography, Zootaxa 5519 (1), pp. 1-37 : 27-32

Moegistorhynchus turneri Barraclough & Colville sp. nov.

( Figs 8.1–8.9 , 10.3–10.4 , 11.2–11.3 , 12 )

Type locality. Groot Winterhoek mountains north of Tulbagh , Western Cape province .

Type material (all in SAMC): HOLOTYPE ♂: “ South Africa, Western Cape, Groot / Winterhoek , 1017m, / S34.10185 E18.3669, 11-Nov.- / 2017, A. Melin & J.F. Colville, / abundant, visiting Wachendorfia / paniculata . ” The holotype is in good condition . PARATYPES: 6♂ 8♀: same data ; 3♀, same data but on last two lines of label: “[ JFC _GW_06: DNA: 3 / legs: RHS].” ; 1♀, same data but “ Grootwinterhoek mtns, nr Veepos / 33 km E. Porterville, 6th Dec. 2010 / Anton Pauw , visiting Wachendorfia ” ; 1♂ 1♀, same data but “ Waboomsberg mtn: S33 15 14.9 / E19 27 26.2; 28th Nov. 2007 / Anton Pauw ; visiting Erica junonia / var. minor and Erica irrorata ” ; 1♂ 1♀, same data but “ S32 59 21.8 / E19 03 57.4; 30th Nov. 2010 / Anton Pauw; visiting Erica junonia / var. minor & E. irrorata ; with pollen” .

Other material (in SAMC): 1♀, Waboomsberg mtn, S33 15 14.9 / E19 27 26.2, 28 November 2007, Anton Pauw , visiting Erica junonia var. minor and Erica irrorata .

Etymology. The species is named in honour of the botanist Ross Turner who first saw these flies in the field at Waboomsberg near Ceres in 2007 and reported them to Prof. Anton Pauw (University of Stellenbosch), who later first collected and pinned them and drew the species to our attention.

Diagnosis. Style with two basal segments. Proboscis short, slightly longer than or reaching up to 1.3 x body length. Postalar callus smooth over entire surface. Wing with some or all of paler sections hyaline and these not creamy white; CuP without any complete crossveins reaching hind margin. Ground colour of abdominal dorsum dark brown to black. Second abdominal tergite almost entirely densely silver pruinescent; pile on tergites 3 and 4 short, much shorter than length of T4 lateral margin and mainly restricted to marginal areas.

Description (both sexes). Body length 15.50– 11.03 mm ( Fig. 8.1 ); wing length 15.01– 11.43 mm; proboscis length 19.14– 13.34 mm. Head ( Figs 8.3–8.4 ): colouring usually very dark brown to black, except scape and pedicel largely yellow-brown (sometimes irregularly darker) and ocellar tubercle and frons occasionally partly or entirely dark yellow to yellow-brown. Postpedicel entirely dark brown to black. Male with anterior ocellus and posterior ocelli separated by broad and deep transverse groove; anterior ocellus and posterior ocelli all about equidistant apart and therefore forming the three corners of an equilateral triangle. Frons with elongate creamy white or yellowish pile, although this often absent medially and, if present medially, then typically recumbent. Style of flagellum with two short basal segments, these subequal in length, but second segment reaching up to 2.0 x length of first segment. Proboscis relatively short, length varies from slightly longer than body length up to 1.3 x body length. Thorax ( Figs 8.5–8.6 ): scutum dark brown to black, although sometimes somewhat paler on postalar calli (also rarely adjacent to wing insertion) and on disc of scutellum. Paired median silver pruinescent vittae extend uninterrupted from anterior margin to scuto-scutellar suture (sometimes variably interrupted with dark ground colour at about three-quarters the distance between anterior margin and scuto-scutellar suture). Scutellum densely silver pruinescent anterolaterally and along posterior margin just posterior to disc. Pile on scutum a mixture of yellow and often black, short but profuse; largely sparse to absent on posterior half (although present here on postalar calli and disc of scutellum and occasionally obvious as sparse, elongate, dark hairs). Postalar callus smooth over entire surface. Legs: almost entirely yellow-brown to medium brown, but sometimes a darker brown (especially hind legs); tarsi notably often darker brown. Fore femur with elongate backwardly directed pale pile, this sometimes reaching up to almost half femur length. Mid and hind femora with sparse inconspicuous ventral pile (a mixture of dark (sometimes) and pale), best developed on basal half to two-thirds. Wing ( Fig. 8.7 ): slender, length 2.8 x to more than 3.0 x maximum width. Infuscation a smoky rather indistinct medium to dark brown. Patterning rather irregular and distributed over much of wing as in figure; hyaline areas not strikingly distinguished or delineated. CuP with short incomplete crossvein extending less than half distance to wing margin (occasionally up to three such crossveins which may be variably developed). Abdomen ( Figs 8.8–8.9 ): relatively compact and slender, width only slightly broader than maximum width of thorax, although sometimes broader in female. Ground colour typically dark brown to black. T1 entirely black and silver pruinescence completely lacking or barely visible; pile dense and short, mostly yellow to cream or white. T2 black, but densely silver pruinescent across entire width (except sometimes along extreme anteromedial margin and sometimes posteromedially, although this may be membrane); pile largely absent. T3 largely dark brown to black, but with striking silver pruinescence/markings over the dark background on anterior half, this most prominent as paired elongate-oval medial areas (transversely directed) and sometimes along lateral margin; posterior margin sometimes with noticeable golden brown pruinescence; pile short, but elongate along anterior margin (not elongate laterally), mostly pale. T4 similarly coloured and patterned, but with more prominent silver pruinescence laterally and sometimes on posterior half. T5 even more extensively silver pruinescent, with small irregular dark area/areas medially and sometimes submedially. T6 silver pruinescent with darker appearance/ colouring restricted to small median area (sometimes this barely evident). Pile on T4–T6 short and sparse, but this longer laterally (typically black in colour, but may be white or yellow). Sternites densely silver pruinescent; pile sparse, except especially elongate (and white) on S3, and also elongate on S4. Male postabdomen ( Figs 10.3–10.4 ): epandrium robust in dorsal view, maximum width somewhat broader than length, with small but prominent apical notch above cerci, apicolateral extremities smoothly and broadly rounded in lateral view. Gonostylus with vestiture along inner medial margin, apical region sharply narrowed and slightly inwardly curved, sharply pointed at extreme apex. Inner gonocoxal process not sharply pointed apically, rather with quadrate apical margin, not narrowed at mid-length. Phallus falling well short of gonostylus apices in ventral view, sharply tapered apically, with dentate subapical margins.

Relationships and distribution ( Fig. 12 ). Moegistorhynchus turneri is most similar to M. strillii , although it is rapidly distinguished by having the abdominal dorsum with a darker (dark brown to black) ground colour and relatively short pile. It appears to be a montane fynbos species. Vegetation type: Hawequas Sandstone Fynbos (FFs10); Kogelberg Sandstone Fynbos (FFs11); Kouebokkeveld Alluvium Fynbos (FFa1); Northern Inland Shale Band Vegetation (FFb1); Winterhoek Sandstone Fynbos (FFs5).

Discussion. We have been aware of this species since 2008 when Prof. Anton Pauw referred a small series of specimens to the first author. Over the years the number of specimens and localities grew considerably. While still undescribed, it was referred to and figured by Barraclough (2017) (see Figs 43.1–43.2). Bellstedt et al. (2020: 30) published (in a popular science article) a picture of M. turneri visiting Erica irrorata at Hansiesberg in the Cape Winelands and, most recently, it has been featured in a field guide to the Ericas of the fynbos and named as a “tangle-veined fly” visiting Erica glandulifera ( Manning et al. 2024: 13) .

The species can be quite abundant in the field at the right time of the year, as recorded by the second author. Based on museum material examined, the species seems to be active between early November and late January.

Newman & Johnson (2021) referred to this new species visiting Erica junonia var. minor , Erica irrorata ( Fig. 11.2 ) and Gladiolus inflatus at Waboomsberg, and visiting Erica daphniflora Salisb. var. daphniflora via an iNaturalist observation at the Matroosberg ( Table 2; Fig. 11.3 ). Another iNaturalist observation is of M. turneri visiting Erica on the Perdekop trail in Mount Rochelle Nature Reserve north of Franschhoek on 23 January 2021. According to Alex Lansdowne (pers. comm.), the Erica is likely E. ventricosa .

The Groot Winterhoek Mountain range where much of the type series was collected is north of Tulbagh and east of Porterville and lies about 120 km north of Cape Town .

Figures

FIGURE 8 (8.1–8.4). Moegistorhynchus turneri sp. nov. (male holotype). 1. Whole body, lateral view. 2. Label data. 3–4. Head. 3. Frontal view. 4. Oblique lateral view, showing detail of antennae: style of flagellum with two short basal segments (arrowed).

FIGURE 10 (10.1–10.4). Male terminalia: dorsal (left) and ventral (right) views. 1–2. Moegistorhynchus perplexus. 3–4. Moegistorhynchus turneri.

FIGURE 11 (11.1–11.4). Photographs of live adult Moegistorhynchus. 1. M. perplexus taking up nectar from Erica junonia var. junonia; note the large amount of pollen on the proboscis (photo credit: Steve Johnson). 2. M. turneri from Waboomsberg taking up nectar from Erica irrorata Guthrie & Bolus (photo credit: Ross Turner). 3. M. turneri from the Matroosberg feeding on Erica daphniflora Salisb var. daphniflora (photo credit: Magriet Brink). 4. Female M. brevirostris apparently ovipositing on a rocky substrate (photo credit: Lily Rose).

FIGURE 12. Distribution of the seven species of Moegistorhynchus across the coastal and montane areas of the Fynbos and Succulent Karoo Biomes (includes confirmed iNaturalist records to February 2024).