Corononcodes ziegleri Kehlmaier, Gharali & Majnon Jahromi

Kehlmaier, Christian, Gharali, Babak & Jahromi, Bahareh Majnon, 2014, A new Corononcodes Speiser from the Palaearctic Region, with a key to species (Diptera: Acroceridae), Zootaxa 3869 (2), pp. 171-179 : 173-177

Corononcodes ziegleri Kehlmaier, Gharali & Majnon Jahromi spec. nov.

(figs 2A–B, 2E, 3B, 4A–B)

Material. HOLOTYPE: ♂, Iran, Ghazvin Province, Ghazvin city, Zarabad village, Plant Medicinal Research Station, 36°28'N 50°24'E, 1520 m, 5.VI.–11.VIII.2009, leg. Babak Gharali, coll. SMTD. PARATYPES: same data as holotype (1♂ MNHU, 1♂ SMTD ( DNA voucher CK611, GenBank voucher HG800023 ), 1♀ SMTD ( DNA voucher CK612 GenBank voucher HG800024 )); Iran, Fars Province, Jahrom, 28°30'N 53˚35'E, 11.–25.III.2013, leg. Bahareh Majnon Jahromi (2♂ 1♀ PCCK, 1♂ 1♀ CSCA, 3♂ SMTD (1♂, DNA voucher CK698 (GenBank voucher HG973062 )).

Etymology. The new species is dedicated to Joachim Ziegler, curator of the Diptera collection at the Museum für Naturkunde in Berlin, Germany, in acknowledgment for his substantial support of our studies.

Description of male. Body length (excluding antennae): 2.0– 2.8 mm (n = 9); wing length: 1.8–2.4 mm (n = 9); wing width: 0.8–1.2 mm (n = 9). Head. Eyes dark reddish brown, dichoptic and bare; occiput visible in dorsal view, black, with white pile; ocellar tubercle slightly surpassing height of scape in lateral view, with short and brownish pile, evenly convex and without ridges; with three ocelli, median ocellus about one-sixth to one-fourth size (HT) of lateral ocellus, situated on anterior face of ocellar tubercle and thus only visible anteriorly (fig. 2E), and not in dorsal or lateral view (use high magnification and powerful light source); scape black, with few white dorsal setae; pedicel yellowish brown, about half length of scape, with short white dorsal setae; flagellum (fig. 2A) yellowish brown, with short white dorsal setae at base, in lateral view subangular apically especially at lower corner, somewhat higher in basal quarter and only weakly bent after basal fourth, length 0.6–0.9 mm (n = 9) or about twice height of compound eye; frons light to mid brown, almost parallel sided, minimum width three ommatidial facets; clypeus white (best seen when proboscis is extended), membranous; proboscis small and black; palpi minute, white with darkened centre. Thorax. Dark brown to black, pleura and postalar callus medium to dark brown; pile short (about same length as on occiput) and white, but pleura almost entirely bare. Legs. Coxa and trochanter light to medium brown, with short white pile (about same length as on occiput), especially on anterior surface of coxa; femur mainly light to medium brown but white in apical fourth to fifth, with short white pile; tibia white with brown ventral spot at end of basal half (absent on hind tibia in HT), with short white pile, no apical spur or row of small sharply pointed projections present (at 144x magnification); tarsomeres white, with short white pile, longest setae dorsally at apex of distitarsus; claws medium to dark brown; pulvilli and empodium white, slightly longer than half length of claws. Wing. As in fig. 3A; membrane hyaline, but cell sc white opaque, hardly any microtrichia present; wing venation reduced; veins translucent except brownish at wing base; no longitudinal vein reaching posterior wing margin; veins M1+2 and M3+4 incomplete basally; two folds present that substitute basal extension of veins M1+2 and vein A1+CuA2 (best seen in female); two cross-veins present (nomenclature uncertain); upper calypter white opaque (can be less pronounced than in cell sc), surface covered with white microtrichia; lower calypter hyaline, rim translucent, surface covered with horizontal streaks appearing to be undulations; halter with almost translucent stem and bright white knob. Abdomen. Medium to dark brown (sternites can be partly paler), dorsally widest at tergite 3, in total about 1.5 times longer than wide, with white pile slightly longer than on thorax (0.04–0.05 mm); cerci white, with white pile longer than on rest of abdomen; genitalia as in figs 4A–B, with aedeagus, parameral sheath of aedeagus, epandrium, gonostyli, ejaculatory apodeme, and small parts of gonocoxite medium to dark brown; larger part of the gonocoxite translucent. Gonostyli small and pointed, fused with gonocoxite.

Female differing from the male as follows. Body length (excluding antennae): 2.4–4.2 mm (n = 3); wing length: 3.4–3.8 mm (n = 2); wing width: 1.5–1.6 mm (n = 2). Head. Pile on occiput darker (brownish); with 3 ocelli; clypeus only visible as a narrow white band that might be due to the retracted state of the proboscis; pedicel and flagellum dark brown; flagellum (fig. 2B) straight with dorsal setae in basal half, laterally at base as broad as pedicel and evenly tapering towards small rounded apex, length 0.36 mm (n = 1) or slightly shorter than height of compound eye. Thorax. Pile brownish. Legs. Entirely medium to dark brown, but femoral-tibial joints and tarsomeres lighter. Wing. Membrane including upper and lower calypters rather evenly brownish infuscated (fig. 3B), but with obvious hyaline folds (basal extension of vein M1+2 and where vein A1+CuA2 would be expected). Wing venation medium brown; halter with stem and knob mainly brown, but knob bright white at top and bottom. Abdomen. Ovate, only slightly longer than wide, widest at tergite 3 and 4, pile brownish (0.06 mm). Terminalia placed at apex of abdomen, not dissected.

Material of C. siculus studied for comparison (figs 2D, 2F). Spain, Canary Islands, Tenerife, Medano, 18.V.1930, leg. A. Cabrera (1♂ MZH); Spain, Canary Islands, Fuerteventura, Los Lagos, ES9675, 6.V.2002, leg. J.T. Smit (1♀ PCTZ); Spain, Cádiz Province, Urbanización Costa Ballena, Playa Ballena, 36°40'50.11''N 6°24' 54.93''W, 22.VI.2014, leg. José Manuel Ayala Landa (1♀ coll. PCJMA).

Differential diagnosis. Predominantly dark brown (except white tibiae and tarsomeres in male) and covered with short pale pile; compound eyes bare and dichoptic; three ocelli present but mid ocellus smaller and placed on anterior surface of ocellar tubercle; mouthparts present and functional; no tibial spur or row of small sharply pointed projections discernable; wing with reduced venation, vein M3+4 incomplete basally, membrane hyaline in male and brownish infuscated in female. Female terminalia placed at tip of abdomen. The observed degree of sexual dimorphism in C. ziegleri comprises body size (female much larger), shape of flagellum (larger in male), coloration of tibiae and tarsomeres (white in male, brown in female) and coloration of wing veins and membrane (mainly hyaline in males, mainly brownish in female).

Corononcodes ziegleri can be distinguished from all African species by the bare eyes that are dichoptic below the antennae. It is closest to C. siculus , the males differing in the lateral shape of the flagellum, the colour of the tibiae and tarsomeres, the presence of the mid ocellus, and by the morphology of the genitalia. Females can only be separated by the presence of the mid ocellus in C. ziegleri , as no apparent differences in antennal shape, wing venation, body coloration etc. could be discerned, based on the material at hand. However, Carles-Tolrá (2008) documented a restricted degree of infuscation of the wing, limited to the basal portion of the membrane in a female specimen from the Spanish mainland. Due to the lack of material it cannot be excluded that the western Palaearctic specimens (Canary Islands, mainland Spain, Sicily) assigned to C. siculus actually represent a species complex.

Remarks. The two populations sampled are about 930 km apart (fig. 5). Uncorrected p-distance in COI between specimens from Ghazvin province in northern Iran (CK611 & CK612) and from Fars province in southern Iran (CK698) was 5.8%. Nevertheless, the material is regarded as conspecific, as there are no distinct morphological features separating the two populations. Also, similar high intraspecific genetic distances have recently been recorded between populations of Acrocera orbiculus (Fabricius) ( Kehlmaier & Almeida 2014) .

Sack (1936), Schlinger (1960) and Barraclough (2001) provided diagnoses of Corononcodes , but a thorough revision of the Panopinae on a generic level is needed to fully define the limits of Corononcodes . This would also help determine whether the Palaearctic species currently placed in Corononcodes should be transferred to a distinct genus as proposed by Barraclough (2001), who briefly discussed the morphological differences between the regional faunas. The Palaearctic species discussed here are closest to C. dimorpha , sharing the sexually dimorphic wing colour (brownish infuscated in female, hyaline in male), the basally incomplete vein M3+4, and the reduced tibial spurs. Also, C. ziegleri has three ocelli like all Afrotropical species. However, unlike the Afrotropical species, the Palaearctic ones have a distinct frons in both sexes, with their compound eyes clearly separated beneath the insertion of antennae. Furthermore, female terminalia are placed at the tip of the abdomen and not ventrally on the abdomen as mentioned in the literature ( Sack 1936; Schlinger 1960; Barraclough 2001).

Kirk-Spriggs & McGregor (2009) comment on the southern African—Mediterranean disjunct distribution of Corononcodes , stating that it might be the result of either isolation following the aridification of the Sahara region during the Pliocene/Pleistocene (cf. “central high Africa corridor”) or that it might have been caused by independent dispersal originating from the Sahel zone via the dust-transporting wind systems of the Western Sahara. With the discovery of an additional species from the Middle East, the distribution of the genus is considerably enlarged, and its biogeographic history extended by the “eastern high Africa corridor” scenario.

No host records are available for Corononcodes , but so far Panopinae have been reared only from mygalomorph spiders ( Araneae : Mygalomorphae). On the Canary Islands, the known distribution of the sole species of mygalomorph spiders ( Titanidiops canariensis Wunderlich ) is restricted to the easternmost islands Fuerteventura, Lanzarote, and La Graciosa ( Izquierdo et al. 2004; Opatova & Arnedo 2011; Wunderlich 1992). The first record here of C. siculus for Fuerteventura makes a parasitoid-host relationship between these taxa conceivable, assuming that T. canariensis is also present on the Western islands. Fully grown females of T. canariensis range from 12–18 mm in total body length ( Wunderlich 1992). As Acroceridae larvae normally emerge from their host before the spider reaches adulthood, the size of the opistosoma of juvenile T. canariensis should therefore be sufficient to harbour fully grown Corononcodes larvae.