Tabanidae (Horse Flies) - Southern Africa's Boletim

Johnson, S. D. 2024. Long‐proboscid horseflies ( Philoliche : Tabanidae) as pollinators of co‐adapted plants in Africa and Asia. Journal of Applied Entomology
DOI:10.1111/jen.13333

https://onlinelibrary.wiley.com/doi/epdf/10.1111/jen.13333

Abstract
Elongated nectar-feeding mouthparts have evolved in several fly families, most notablyNemestrinidae, Bombylidae and Tabanidae. Plants pollinated by these “long-proboscidflies” tend to have relatively specialized pollination systems. In this review, I focuson the blood- and nectar-feeding horsefly genus Philoliche (Tabanidae: Pangoniinae)which includes species that are important pollinators of plants in Africa and, to alesser extent, in Asia. The nectar-feeding mouthparts of flower-visiting Philoliche spe-cies range from 5 to 65 mm in length, with considerable intraspecific variation evidentin some taxa. Plants pollinated by Philoliche species tend to have corolla tubes (orhighly exerted reproductive structures) that match the proboscis dimensions of theirpollinators. Some Philoliche species and their nectar host plants show population-levelcovariation in proboscis lengths and flower depths that is indicative of co-adaptation. Isummarize existing information on the distribution and morphology of Philoliche spe-cies known to pollinate flowers as well as the identity, morphology and nectar proper-ties of plants pollinated by these insects. This survey identifies some Philoliche speciesas keystone pollinators. Distinct guilds of plants are adapted to different horsefly spe-cies in different geographical regions and are generally ecologically reliant on theseinsects, although some plant species share tabanid and nemestrinid pollinators thatare functionally similar on account of convergent evolution of their proboscis dimen-sions. Lack of information about the larval biology, nectar host plants, fire ecology anddispersal distances of Philoliche species is the biggest challenge for the conservationof these specialized pollinators and the plants that depend on them.K E Y W O R D Scoevolution, floral adaptation, floral syndrome, fly pollination, nectar, pollination, proboscislength

Original description (Tabanus nanus) in:
Wiedemann, C.R.W. 1821. Diptera exotica. Sectio II. Antennis parumarticulatis.
https://www.biodiversitylibrary.org/item/50314#page/127/mode/1up
Translated from Latin:
Blackish; abdomen brown, threefold spotted; with white spots and incisions; with tibiae and tarsi ochreous.
Cape.
[...] Antennae brown at the base, the third article is striking ferrugineous, antennal tip black; [...] palps pale
brown; frons gray; callous brown. Thorax blackish, with a central brown vitta and whitish lateral vittae; the sides of the thorax are brown; pleurae slate-grey, with white pubescence. Abdomen brown, with a median stripe of triangular white spots, and on both sides with bright grey subsquare spots; the lateral margins of the segments are yellow-brown. The wings are very clear with a blackish-brown stigma; halters yellowish, knob brown below, above white. Femora anteriorly black-brown.

iNat observation: https://www.inaturalist.org/observations/208443341

Distribution: Known only from the Western Cape.

An ashy-grey black species (from the Cape). Wings brownish-grey with distinct eye-spots (ocelli).
Antennae reddish brown, black at the tip; first joint distinctly inerassate.
Thorax ashy-grey black with three white stripes, the lateral ones may be reduced to two white spots.
Abdomen ashy-grey black; segments with white hind borders and white spots on each segment; median white longitudinal line (apically dilated on the segments).
Legs brown with two white rings on the tibiae.

Description by Wiedemann:
https://www.biodiversitylibrary.org/item/50649#page/259/mode/1up

Taxonomic note:
H. occellata may be conspecific with H. obscura and H. spectabilis; comment from Usher 1972:
"H. ocellata Wiedemann 1819; H. obscura Loew 1857; H. spectabilis Oldroyd 1952
I have tentatively grouped these species together, being quite unable to decide where the specific
boundaries lie. Increasingly more material has become available for study and reveals that this apparently
is either a very variable single species or a complex of very closely associated species which only biometrical analysis may be able to elucidate. Two specimens of H. obscura from the Berlin Museum, both labelled 'type', are indistinguishable from undoubted H. ocellata from the S.W. Cape. The holotype of H. spectabilis is from Richmond in the Karoo, a dry area. From Niewoudtville where a para type is recorded the NM has a series of well over 100 specimens showing predominantly spectabilis characters but with sufficient variation and the inclusion of ocellata characters to be perplexing. When linked with specimens from localities ranging from Nieuwoudtville and the dry Karoo areas to the damper areas of the S.W. Cape (still winter rainfall), then around the coast to all-year-round and finally summer-rainfall areas, the variation appears to be continuous. There is a predominance of characteristic features in different type of habitat, the most perfect 'ocellata' specimens being from M (S.W. Cape) and the most extreme 'spectabilis' from dry, high areas in Lesotho (H)."

iNat observation:
https://www.inaturalist.org/observations/59427769

Thorax blackish with indistinct pale lines on the anterior half. Scutellum almost wholly dark. Abdomen blackish, hind borders of segments white, white spots on the third and subsequent segments. Antennae deep black, reddish at the baseof the third joint; first joint distinctly inerassate. Hind tibiae with two rings of light colour.

Original description by Loew:
https://www.biodiversitylibrary.org/item/35325#page/66/mode/1up

Illustration of wing:

Usher (1972) treated both H. obscura and H. spectabilis as H. ocellata and hypothesised synonomy without formalising it.

iNat observation:
https://www.inaturalist.org/observations/158553003

A brown species. Antennae distinct: first segment shiny brown, extremely thickened; third segment rusty red with black tip. Thorax brown with three white longitudinal lines, the median one extending down the scutellum; crescentic marks on hind border absent. Abdomen brown with pale patches, forming two longitudinal stripes. Legs brownish with lighter but not white rings on the tibiae.
The wings are brown and look like this:

Original description by Loew:
https://www.biodiversitylibrary.org/item/35325#page/69/mode/1up

Recorded from Gauteng and KwaZulu-Natal.

iNat observation:
https://www.inaturalist.org/observations/36671131

Original description by Walker:
https://www.biodiversitylibrary.org/item/37471#page/470/mode/1up
Blackish brown. Head whitish on the vertex and behind, white beneath; front with three black whitish-bordered spots, the middle one small and hindward. Palpi while. Antennae black, rather longer than the head. Thorax with three much interrupted white stripes; the middle one dilated hindward. Scutellumm with a dark border. Abdomen glaucous-white towards the base beneath and on each side above and on the hind borders of the segments. Legs black; tibiae white towards the base; middle tibiae with a white band; hind tarsi white at the base. Wings whitish, with various blackish gray dots, and with two diffuse blackish gray partly whitish-dotted bands; stigma black. Halteres white.

Description by Loew (Haematopota dorsalis):
https://www.biodiversitylibrary.org/item/35325#page/70/mode/1up
--> Abdomen with sublateral white spots on the apical segments (not mentioned by Walker).

Illustrated in Austen 1908:

Photo of wing in Ricardo 1906:
Ricardo, G. (1906). Notes on the genus Hæmatopota of the family Tabanidæ in the British Museum collection. Annals and Magazine of Natural History, 18(104), 94–127. doi:10.1080/00222930608562585
https://sci-hub.st/https://doi.org/10.1080/00222930608562585

Photos in Smit 2019:
https://repository.up.ac.za/bitstream/handle/2263/76793/Smit_Abundance_2019.pdf?sequence=1

This species is widespread in the Afrotropical region.

iNat observation:
https://www.inaturalist.org/observations/171292363

Length 16 mm. Black; frons, antennae, palpi, proboscis, except tip, legs, and tip of abdomen, orange. Cheeks, occiput and pleurae with sparse black pile; pile of legs short and yellow. Halteres black, knobs white. Wings black, with small hyaline spot in apex of first basal cell.

Original description by Loew (Silvius pertusus):
https://www.biodiversitylibrary.org/item/35325#page/40/mode/1up

Widely distributed in the Afrotropical region.

iNat observation: https://www.inaturalist.org/observations/67761645

This species is unmistakable: The abdomen has a median broad grey stripe and broad grey sides, there are small spots inbetween on each segment. The wing looks like this:

Original description by Loew:
https://www.biodiversitylibrary.org/item/35325#page/69/mode/1up

This species occurs in the north-eastern part of South Africa and Zimbabwe.

iNat observation: https://www.inaturalist.org/observations/37398431

Diagnosis from Wiliams 2022:
Abdomen with three well-defined, parallel-sided, yellowish grey longitudinals stripes, all equally clear, and about equal in width
https://repository.up.ac.za/bitstream/handle/2263/83323/Williams_Evaluating_2022.pdf?sequence=1&isAllowed=y

Original description by Ricardo:
Ricardo, G. 1900. Notes on Diptera from South Africa (Tabanidae and Asilidae) [part]. Annals and Magazine of Natural History (7) 6
https://www.biodiversitylibrary.org/page/15629618#page/183/mode/1up

Photos of holotype (Natural History Museum London):
https://www.gbif.org/occurrence/1056126541

The geographic distribution of this species is likely confined to the southern parts of the Afrotropics.

iNat observation:
https://www.inaturalist.org/observations/178671721

Diagnosis from Morita:
P. aethiopica is distinguished from all species in the rondani species group as follows: ♂ eye facets of similar size, longer lappets with the dorsal process of tarsus 2 extending beyond proximal margin of tarsus 4; ♀index of frons divergence greater than 2.1
Posterolateral margin of segments 3–7 with tufts of black or white hairs as follows: 3 – black, 4 – white, 5 – black, 6 – white, 7 – white.
Male: eyes meeting until slightly above antennae leaving a small triangle of a frons.

This species is divisible into three morphotypes that overlap in distribution and differ distinctly in proboscis length. The Albany form is larger and consistently has a spot of white hairs in the center of the hind margin of the fourth segment of the abdomen. The Natal form is slightly smaller and may have a white fringe along the entire hind margin of the fourth segment of the abdomen, or a spot (like the Albany form) or no white hairs at all. The Zimbabwe form is similar in size to P. rondani , and consistently has a white fringe along the entire hind margin of the fourth abdominal segment.
https://treatment.plazi.org/id/B17087D25920FFE93051FD87FE96FBF4