Moegistorhynchus braunsi Bequaert 1935
Creators: name: Barraclough, David A.
name: Colville, Jonathan F.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Nemestrinidae
Moegistorhynchus
Moegistorhynchus braunsi

description: Moegistorhynchus braunsi Bequaert, 1935
(Figs 2.1–2.9, 9.1–9.2, 12)
Moegistorhynchus braunsi Bequaert, 1935: 495; Bernardi, 1973: 269; Bowden, 1980: 374.
Type locality. Stellenbosch, Western Cape province.
Type material. Holotype in MCZC and paratypes in NMSA. South Africa: Western Cape: HOLOTYPE: ♂: “Capland / Stellenbosch / Nov 9 1926 / Dr. H. Brauns. ”; “ J. G. Bequaert det., 1933: / Moegistorhynchus / braunsi J. Beq. / holotype ♂ ”; “HOLO TYPE” [red card]; “ MCZ TYPE / 35327 ” [red card]. Note that we have not physically seen the holotype, which is deposited in MCZC. Instead, we have relied upon an excellent series of six images taken of the holotype (Museum of Comparative Zoology, n.d.), which are available online (https://mczbase.mcz.harvard. edu/guid/ MCZ: Ent:35327). These images of the entire body, head, thorax, wing and abdomen, as well as of the label data, confirm that the holotype is conspecific with the paratypes and other material deposited in NMSA. The label data also tally with the label data cited by Bequaert in the original description. It should be noted that much of the abdomen of the holotype has been detached from the body and is stuck to card pinned beneath the specimen; the postabdomen has also been dissected and is stored in a microvial. There is, as stated in the original description, apparently an “ allotype ” in MCZC, but we have not seen images of this specimen. PARATYPES: 3 ♂, 1 ♀, with appropriate type labels and dated 4, 5 and 9 November (the Nov. 9 paratype with a label referring to Gladiolus cuspidatus).
Other material: same data but 1 Nov. 1926 (3 ♂, NMSA); 2 Nov. 1926 (3 ♂, 2 ♀, NMSA); 4 Nov. 1926 (3 ♂, NMSA); 5 Nov. 1926 (2 ♂, NMSA); 9 Nov. 1926 (1 ♂, NMSA); 9 Nov. 1926 (1 ♀, SAMC); 25 Oct. 1927 (1 ♂, SAMC).
Diagnosis. Postpedicel entirely pale; style with two basal segments. Proboscis strikingly elongate, more than twice body length. Postalar callus smooth over entire surface. Wing with transparent or hyaline markings, such areas never an opaque creamy white. Second abdominal tergite almost entirely silvery pruinescent across its width. Abdominal dorsum with posterolateral sections of T3 and T4 without obvious dark pile. Epandrium not divided into two obvious lobes dorsally and with small apico-medial notch only; gonostylus broadly rounded apically.
1 The postpedicel in Fig. 6.4 (that of the female holotype) is atypically pale because of fading resulting from the age of the specimen.
Redescription (both sexes). Body length 11.97–15.34 mm (Fig. 2.1); wing length 13.34–15.08 mm; proboscis length 39.23–44.18 mm. Head (Figs 2.3–2.4): colouring mostly yellow to yellow-brown with scape and pedicel notably yellow or yellow-brown. Postpedicel entirely yellow to yellow-orange. Male with anterior ocellus and posterior ocellus separated by deep transverse groove; anterior ocellus closer to posterior ocellus than posterior ocelli are to each other, therefore delimiting a compressed triangle. Frons with elongate yellow or cream pile, this absent medially, except sometimes typically recumbent anteriorly. Style of flagellum with two short basal segments, these subequal in length but second segment may be slightly longer than first segment; second segment may be very difficult to discern and may be partially fused with adjacent segments. Proboscis elongate, length 2.5–3.0 x body length. Thorax (Figs 2.5–2.6): scutum yellow to yellow-brown to medium brown or orange and only ground colour beneath median and submedian vittae dark (this black). Paired median silver pruinescent vittae extend from anterior margin to half to two-thirds distance to scuto-scutellar suture (posterior section a pale to dark orange). Scutellum silver pruinescent anterolaterally and along posterior margin just posterior to disc. Pile on scutum yellow but sometimes whitish on posterior half, short but profuse; largely sparse to absent on posterior half (although present here on postalar callus and especially disc of scutellum and along posterior midline area). Postalar callus lacking a noticeable acute cuticular protrusion near middle. Legs: almost entirely yellow. Fore femur with relatively elongate backwardly directed whitish pile, this sometimes reaching up to one-third femur length. Mid and hind femora with sparse ventral pile (similarly coloured) along basal half to two-thirds of mid femur and along basal one-quarter to half of hind femur. Wing (Fig. 2.7): very slender, length at least 3.5 x maximum width. Infuscation an indistinct smoky brown, sometimes a darker brown. Patterning rather irregular and distributed over much of the wing as in Fig. 2.7; hyaline areas not strikingly distinguished or delineated. CuP with one to three short crossveins, these obviously incomplete and do not reach hind margin of wing; crossveins occasionally absent or very short, very rarely one crossvein complete. Abdomen (Figs 2.8–2.9): somewhat compact, width broader than maximum width of thorax, although sometimes broader in female. Ground colour very varied, ranging from dark brown to yellow or yellow-brown or orange. T1 entirely dark and silver pruinescence completely lacking or barely visible; pile dense and short, mostly cream to white or yellow. T2 typically densely silver pruinescent across entire width (except posteromedially or occasionally anteromedially, but this may be membrane); pile largely absent. T3 largely yellow-brown to orange, but with striking silver pruinescence/markings on anterior half as paired elongate-oval areas medially (transversely directed), these areas with dark colour between and/or around them and this sometimes along anterior margin and laterally; silver pruinescence sometimes extending laterally and in female may occur laterally and faintly along posterior margin; pile moderately short and sparse over anterior half to two-thirds, whitish to pale yellow, elongate along anterior margin and occasionally posterolaterally; pile longest anteriorly, this length about one-third to half length of T3 lateral margins, pile sometimes absent over silver pruinescent elongate-ovoid areas. T4 similarly coloured and patterned, but median darker colouring may be more extensive and extend laterally; silver pruinescence sometimes evident laterally and along posterior margin in female; pile typically short and sparse, sometimes more profuse on anterior half and posterolaterally, this white to yellow, longest hairs one-third to half length of T4 lateral margin. T5 medium to dark brown, but with darker brown colouring anteromedially, silver pruinescent markings similar to those on T4; pile whitish, moderately long and restricted to lateral margins (and sometimes on anterior half). T6 medium brown and silver pruinescent, slightly darker medially; pile largely absent. Sternites usually mostly yellow with irregular dark brown markings (restricted), but often darker in female, being mostly dark brown to black; pile notably elongate and white on S3. Male postabdomen (Figs 8.1–8.2): epandrium very well developed and hooded in dorsal view, maximum width somewhat broader than length, with very small apical notch above cerci, apicolateral extremities very broadly rounded in lateral view (Fig. 8.1). Gonostylus with no vestiture along inner medial margin, well developed, broad and squat in appearance, apical region broadly rounded apically and not inwardly curved. Inner gonocoxal process not sharply pointed apically, here rather broadly and bluntly tapered, apical region with very small marginal teeth; prominently arched at mid-length. Phallus apex extending beyond gonostylus apices in ventral view, arrow-like apically with minutely dentate margins.
Relationships and distribution (Fig. 12). Moegistorhynchus braunsi is most similar to M. perplexus Bequaert, 1935 (distinguished mainly by colour characters and characters of the male terminalia), although unlike M. perplexus, M. braunsi is currently known to occur much further south and only from the Stellenbosch area. Vegetation type: Swartland Shale Renosterveld (FRs9).
Comments. We have seen a single female in SAMC from Somerset West, collected in October 1940 by C. H. Lawrence. Unfortunately, both postpedicels and styles are missing. We have excluded this specimen from the redescription of M. braunsi as the median silver pruinescent vittae on the scutum are complete to the scuto-scutellar suture (incomplete in all other material of the species). There is a small possibility that it could represent a species near M. braunsi.
Otherwise, it appears that this striking, large, and unusually coloured species, known only from the well-collected Stellenbosch area, is possibly or even probably extinct. The entire Stellenbosch area is now an extensively altered landscape (now largely urban and agricultural) and has been heavily collected by entomologists and pollination biologists based at the University of Stellenbosch over many years. However, the species was last collected by Brauns 97 years ago in October 1927. It is unclear where exactly it was collected.
Note that according to Bequaert (1935: 498), Dr Brauns, the collector of all the specimens of M. braunsi, commented that he had collected many specimens visiting “ Gladiolus cuspidatus ” (a synonym of Gladiolus carneus D. Delaroche). This is confirmed by a label on a few of Brauns’s specimens. The species was collected in October and November only.
description: Published as part of 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, pp. 1-37 in Zootaxa 5519 (1) on pages 6-9, DOI: 10.11646/zootaxa.5519.1.1, http://zenodo.org/record/13915454