Callicera exigua, Smit, John, 2014

Smit, John, 2014, Two new species of the genus Callicera Panzer (Diptera: Syrphidae) from the Palaearctic Region, Zootaxa 3779 (5), pp. 585-590 : 587

Callicera exigua sp. nov.

( Figure 1 )

Type material. Holotype: ♀. Label 1: “ Russia, Altay Republic; Kosh-Agach Chuya river; 50°04’N 88°24’E; 4.vii.2013 1750 m a.s.l.; Leg. J.T. Smit.” Label 2: “ RMNH.INS.; 557232” [including a QR-code]. Label 3: “ HOLOTYPE ♀; Callicera ; exigua Smit ; Det. J.T. Smit 2014.”

The holotype female is in good condition, though with clear signs of wear: e.g. the wings are damaged in the posterior part and the hairs of the mesoscutum, scutellum and the middle of the tergites are rubbed off. The right middle-leg is removed for DNA sequencing. The holotype is deposited in RMNH.

Description. Body length (excluding antennae): 11 mm. Head. Entirely shining black, orange-red haired. Face with semi ad-pressed hairs and a thin, clearly bare line in the middle, between the antennae and mouth-edge and broader ones on the genae. Frons less densely haired than face and hairs not ad-pressed. Above the lunule bare from eye to eye. Vertex with two bare spots between the posterior ocelli and the eye. Head with hardly any dusting, frons with two inconspicuous dusted spots underneath the hairs, more clear towards the eye margin. Face with a narrow line of grey dusting along the eye margin, and the lower half of the occiput only slightly dusted. Antennae black, scape only slightly lighter dark-brown basally. Style short, black, with only the tip white. Antennal ratio: 1; 0.75; 1.7; 0.35 (scape; pedicel; basoflagellomere; style). Eyes whitish yellow haired in anterior half. Thorax. Black, shining slightly metallic bronze. Entirely orange-red haired, on the pleurae somewhat lighter and on the posterior rim of the scutellum turning even whitish. Hairs on the posterior half of the mesoscutum, as well as dorsally on the scutellum, rubbed off for the greater part. All pleurae as well as the mesoscutal dorsum entirely shining, without any dusting. Wings. Infuscated in the anterior half and with a clear dark cloud in the middle. Veins largely orange-yellow in the basal half of the wing, turning darker brown in the infuscated part, except R1. Legs. All legs with the coxa and trochanter black, and the femur, tibia and all tarsomeres entirely red, the claws bicoloured, red basally and black apically. Coxae and trochanters entirely red haired. Abdomen. Same colour as thorax; black and shining slightly metallic bronze. Abdomen entirely orange-red haired, though in the middle of the tergites much of the hair covering is rubbed off. Hairs on anterior corners of the second tergite, as well as on the lateral margin of second and third tergites, whitish. Tergites without any dull markings, entirely shining.

Diagnosis. Differs from all other known Callicera species from the Palaearctic Region, by the infuscation on the anterior half of the wing. The Oriental C. doleschalli Verrall , described from Myanmar, has entirely orange legs and some infuscation on the wing. Photos of the holotype, held in BMNH, have been examined revealing that the infuscation is confined to the middle of the wing. Also, the antenna as a whole are much shorter that those of C. exigua sp. nov.

Etymology. The specific epithet (adjective) emphasizes the small size of this species.

Distribution. Russia, Altay.

Habitat. The female was caught flying in a shallow valley containing a brook with dry thicket alongside and an abundance of yellow flowering Cistus sp. ( Cistaceae ). Despite the fact that mature trees were lacking a few other saproxylic species were quite common: Ceriana conopsoides (Linnaeus) and Mallota eurasiatica Stackelberg. On the other hand a few hundred metres from this locality a number of old poplar trees were found along the river Chuya, therefore these hoverflies were probably drawn in by the flowers instead of actually having breeding sites in the valley.

Remarks. This is one of four species currently known from the Eastern Palearctic region, the other three species recorded are: C. aenea , C. rufa and C. ziminae . The latter has been described from Tajikistan and is thus far not known outside this country ( Krivoscheina & Kuznetzov 2001). The other two species have a wide distribution in the Palaearctic, ranging from Spain and Britain (except aenea ) in the west to Korea and the Russian Far East in the East ( Marcos-Garcia et al. 2002; Mutin & Barkalov 1999; Speight 1991; Han & Choi 2001).

Figures

FIGURE 1. Female holotype Callicera exigua sp. nov.: A: head in dorsal view. B: head in lateral view. C: dorsolateral habitus. D: dorsal habitus.