A new species of the genus Suillia Robineau-Desvoidy, 1830 (subfamily Suilliinae), namely Suillia stuckenbergi sp. n., is described from Cameroon and Kenya in the Afrotropical Region. This finding constitutes the first record of the genus Suillia in Cameroon, and the westernmost record for the genus in the Afrotropical Region. Modified key couplets are provided for Cogan's key to the Ethiopian species of Suillia in order to facilitate recognition of the new species. The systematic position of the newly described species is briefly discussed.
The genus Suillia Robineau-Desvoidy, 1830 is the largest genus of the family Heleomyzidae, with ca 130 described species, and is also the most widely distributed genus in the Afrotropical Region. Cogan (1980) listed 18 species in the Afrotropical Catalogue. Suillia picta (Wiedemann, 1830) was the first species of the genus described from the Afrotropical Region. This is a common species known from Mozambique, South Africa and Zimbabwe and its close relative, S. ingens (Lamb, 1917) is known from a further five African countries, viz. the Democratic Republic of the Congo, Kenya, Rwanda, Tanzania and Uganda (Cogan 1971). Only one species, S. variegata (Loew, 1862), is also widely distributed outside the Afrotropics and is common along the Mediterranean and elsewhere in Europe. The occurrence of S. similis (Meigen, 1830) in Kenya, as recorded by Cogan (1971), is still unconfirmed, and this species should be removed from the Afrotropical list, as it represents a Palaearctic element. Cogan highlighted this case himself when he noted that the Kenyan record was based on only a single damaged specimen, which unfortunately could not be traced in the collections of Muséum national d'Histoire naturelle, Paris, France, during a visit in 2008. Within S. aspinosa (Lamb, 1917), Cogan recognised three subspecies, but these have subsequently been found to differ from one another, not only in chaetotaxy and body colouration, but also in the structure of the male terminalia and should, therefore, be regarded as valid species, as indicated in the key by Cogan (1971). One species, S. keiseri Cogan, 1971, known only from Madagascar, bears one to two large anepisternal setae, which are also present in one Neotropical species (S. intens Giglio-Tos, 1893) and this character state should be regarded as a homoplasy shared by two distant species.
During a preliminary systematic study undetermined material of Suillia was examined for the first time from Cameroon and Kenya. This material is significant, as it was collected in high mountain areas between 1400 and 3000 metres above sea level, confirming Cogan's (1971, 1977) assumption that Afrotropical representatives of the genus Suillia may be chiefly restricted to afforested mountain areas, where the climate is more moderate and larvae are able to develop in basidiomycete fungi.
This paper is dedicated to the memory of the outstanding entomologist Brian Roy Stuckenberg (1930–2009), who collected many of the heleomyzid flies studied by Cogan in 1971.
MATERIAL AND METHODS
The terminology of male terminalia follows Sinclair (2000), with modifications from Zatwarnicki (1996). Abbreviations of ratios and measurements follow Woźnica (2003, 2006). Images were captured with a Leica JVCKYF75 digital camera attached to a Leica M205C stereomicroscope. Details of male terminalia were prepared using the light microscope and computer graphic techniques. Terminalia of paratypes were extracted and cleared in 10 % potassium hydroxide (KOH) at ambient temperature, rinsed in water and preserved in glycerine in a micro vial pinned beneath the source specimen.
Bilaterally symmetrical structures in species descriptions are cited in the singular.
The following institutional codens are used for museum collections cited in the text: MNHN — Muséum national d'Histoire naturelle, Paris, France; TAU — Department of Zoology, Tel Aviv University, Tel Aviv, Israel.
Genus Suillia Robineau-Desvoidy, 1830
Revised key couplets for Cogan's (1971) key to Afrotropical Suillia
In Cogan's key, S. stuckenbergi sp. n. runs to couplet 18 (“Suillia species A”). Couplets 18–20 below replace those of Cogan (1971) to enable identification of the new species.
18 Wing with distinct infuscation over point of insertion of R2+3 in costa, together with apices of R4+5 and M. Dorsal surface of scutellum entirely setulose, setulae not confined to margins of disc 19
— Wing with costal margin broadly infuscate, lacking distinct infuscation over apex of R2+3. Dorsal surface of scutellum glabrous, with a few sparse setulae confined to margins of disc 20
19 Mesonotum and scutellum buff brown. Abdomen predominantly dark, but with lateral margins of all tergites pale Suillia sp. “A”
— Mesonotum and scutellum pale orange. Abdomen predominantly yellow, but with dark brown margins of tergites 2–5 stuckenbergi sp. n.
20 Wing with infuscation over posterior cross-vein extending into r4+5, but not fusing with broad costal infuscation. Abdomen predominantly black ovata Collart
— Wing with infuscation over posterior cross-vein not extending into r4+5. Abdomen broadly yellow laterally balteata Lamb
Suillia stuckenbergi sp. n.
Etymology: Named in honour of the late Brian Roy Stuckenberg, in recognition of his significant contributions to the study of Afrotropical Diptera.
Diagnosis: Body generally pale, yellowish orange, with whitish and blackish patches on darkened wing membrane (Fig. 1). First flagellomere elliptical, orange and slightly darkened in dorsal half. Arista long plumose. One large black vibrissa and an additional seta present (ca 0.5× as long as the dorsal, sometimes longer). Cheek brownish yellow. Dorsally mesonotum yellowish orange, with 1+4 dorsocentrals, not arising from macula. Scutellum with broad bare area dorsally, except some setulae in lateral third. Thoracic pleura pale orange, with narrow but distinct dark brown fascia, anepisternum and anepimeron glabrous. Wing with r—m and dm—cu crossveins broadly brown maculate. Apex of each longitudinal vein with distinct brown infuscation. R1 with large, brown egg-shaped macula in apical part. Three iridescent whitish patches over crossvein areas. Abdomen yellowish, with dark blackish brown margins from segment 2.
Male & Female.
Body length (minus antennae) 5.8–6.5 mm (♂) and 5.6–6.7 mm (♀).
Head: Head ratio: 1.16:1.25; orbital plate parallel to eye margin and shiny yellow; frons yellowish brown; ocellar triangle blackish brown; posterior part of head pale orange, except for silver pollinose whitish area around supracervical black setulae; face yellowish without spots, slightly protuberant in middle; cheek brownish yellow; area posterior to vibrissae dark brown maculate, remaining part yellowish. Cheek: eye ratio: 0.18:0.21; 1 strong black vibrissa with additional seta (ca 0.5× as long as dorsal, sometimes longer); palpus yellowish with slightly darkened apex, proboscis yellowish, apically more brownish; antenna yellowish brown; first flagellomere egg-shaped, yellowish brown, more darkened dorsally; arista brown, long plumose, with rays much longer than diameter of basal segment; first flagellomere ratio: 1.86:2.09; flagellomere: cheek ratio: 0.93:1.00.
Thorax: Prosternum whitish yellow, with 2 or 3 pairs of pale brown setulae; mesonotum entirely yellowish orange, with 1+4 dorsocentral setae, not arising from dark spots; proepisternum with sparse brown setulae scattered across surface; pleural part of thorax yellowish orange, with thin lateral dark brown fascia running from anterior part of postpronotum to wing base; postpronotum, notopleural area, anepisternum and meron pale orange; katepisternum with 1 strong black seta and some smaller setulae; anepisternum and anepimeron glabrous; meron bearing a few brown setulae at posterodorsal corner; scutellum and postscutellum yellowish orange; scutellum slightly elongate and pointed apically, with >20 small blackish setulae at lateral margin (Fig. 2); ventral surface of scutellum glabrous.
Legs: All, including coxa, yellowish orange; fore femur enlarged in male, with 8 strong black setae anterodorsally and setula-like, long rusty-brown setae posteroventrally; mid femur with two rows of dorsal setae (5 in dorsal row and 2 or 3 in ventral row); hind femur with ca 11–13 blackish setae arranged in two rows in male and 7–9 black dorsal setae in female; one medium-sized curved black seta at the apicoventral part of mid femur in both sexes; male tibia with long, thick setosity; mid tibia with one medium-sized black seta in the apicoventral part and 3 black setae of variable length in the apical anterior part; tarsomere 1 of male fore and mid leg with long setosity ventrally; tarsomeres 2,