Citrogramma asombrosum Mengual, 2012

Mengual, Ximo, 2013, Notes on Citrogramma Vockeroth and Eosphaerophoria Frey (Diptera: Syrphidae), Zootaxa 3745 (3), pp. 388-396 : 389-391

Citrogramma asombrosum Mengual, 2012

Figures 1–3 , 8.

Citrogramma asombrosum Mengual, 2012 . Zool. J. Linn. Soc. London, 164: 128, descr., figs, key. Holotype: m, New Caledonia: South Province, Nouméa, Mount Koghi [INHS, Champaign] by original designation.

Differential diagnosis (based on Mengual 2012). Species only known from New Caledonia, with black facial vitta, triangular black area on frons, costal cell microtrichose, and scutellum with a medial dark macula not reaching anterior margin. Citrogramma asombrosum is similar to C. bicornutum Vockeroth, 1969 , but C. asombrosum has cell bm bare on anterobasal section, cell cup is entirely microtrichose and yellow abdominal fasciae are broader than in C. bicornutum .

Mengual (2012) described C. asombrosum based on a single male from New Caledonia. After the study of the CSCA material, two female specimens of this species from New Caledonia were found. The description of the female of C. asombrosum is given below.

Material examined. 2 females, NEW CALEDONIA: South Province: Mt. Ningua, 1100 m, 21.746° S 165.156° E, 12–21.xii.2000, ex: Malaise trap, L. J. Boutin [1 female, CSCA; 1 female, ZFMK].

Description of female. Head. (Fig. 8) Face with facial tubercle, gradually sloping dorsally, more abrupt ventrally, yellow with medial black vitta, from oral apex to antennal base, narrower than yellow lateral areas of face, yellow pilose; gena yellow, yellow pilose; dichoptic; lunule brown; frons yellow with anteromedial black triangular area pointed posteriorly, black pilose; vertical triangle black, black pilose; ocelli yellowish; antenna dark brown, black pilose on scape and pedicel; basoflagellomere orange, dark dorsally; arista brown, with short pili basally, shorter than the arista width; occiput black, silver pollinose on ventral 2/3, golden pollinose on dorsal 1/3, white pilose on ventral 2/3, black pilose on dorsal 1/3. Thorax. ( Figs 1, 2 ) Scutum black with dorsomedial area uniformly grey pollinose with bluish metallic iridescence, lateral yellow vitta and sublateral matte black vitta, black and yellow pilose, but notopleuron yellow pilose with some black bristle-like hairs posteriorly; postpronotum yellow; notopleuron yellow continuing until scutellum, with postalar callus entirely yellow and black pilose; scutellum yellow with dorsomedial broad diffuse dark macula not reaching anterior margin, creating narrow yellow margin all around, black pilose. Pleuron mostly black, except anterior anepisternum yellow; proepisternum yellow; posterior anepisternum yellow on posterior 2/3; anepimeron yellow, dark posterodorsally; katepisternum with large dorsal yellow macula; katepimeron and metaespisternum yellow; katatergum yellow, black posteriorly. Pleuron entirely yellow pilose, slightly yellow pollinose. Metasternum yellowish. Calypter yellow, darker ventrally, with brownish hairs on margin; plumula yellow; halter yellow; spiracular fringes yellow. Wing. Wing membrane hyaline, stigma dark brown, entirely microtrichose except cell bm anterobasally. Alula microtrichose, broad, broader than cell bm. Legs. Procoxa yellow, mesocoxa black, metacoxa yellow; pro- and mesofemur yellow, slightly brownish dorsally, mainly black pilose with yellow hairs basally; pro- and mesotibia yellow, black pilose; pro- and mesotarsus brown; metaleg black, black pilose. Abdomen. ( Fig. 3 ) Slightly oval in shape (not strictly parallel-sided), abdominal margin inconspicuous. Dorsum mainly black, black pilose dorsally and laterally except 1st tergum yellow pilose laterally and 2nd tergum yellow pilose laterally on anterobasal 1/2; 1st tergum black, black pollinose; 2nd tergum black with two mesolateral triangular rounded-tip yellow maculae, yellow lateral margin on anterior 1/2; 3rd and 4th terga black with broad yellow fascia (1/3 to 2/5 of tergum length) on anterior 1/ 2 of tergum, with anterior narrow black fascia; 2nd, 3rd and 4th terga black pollinose except posterior 1/3; 5th tergum black with anterior broad yellow fascia, black pollinose on black areas; sterna yellow, black pilose except 1st tergum yellow pilose, 3rd and 4th sterna brownish laterally.

Variation. One of the two females is lighter, with metafemur yellowish on basal 1/3. This lighter female also has the two yellow maculae on 2nd tergum slightly joined medially.

Length (N = 2). Body, 8.3 mm (8.0–8.6); wing, 7.7 mm (7.9–7.5).

Geographical distribution. New Caledonia.

Remarks. One morphological characteristic is unusual: a bare metasternum. This character state is not common in this genus, and it is only found otherwise in Citrogramma quadricornutum Vockeroth, 1969 from Papua New Guinea. The interesting fact is that the holotype male has a pilose metasternum (Mengual 2012), suggesting that the pili of the metasternum of these females were rubbed off in the Malaise trap, or during mounting. Mengual (2012: 132) found a female of Citrogramma chola Ghorpadé, 1994 also with a bare metasternum.

Figures

FIGURES 1 – 3. Citrogramma asombrosum, female (scale 2 mm). 1. Lateral view; 2. Dorsal view, habitus; 3. Posterior view, abdomen. Figures 4 – 7. Citrogramma pennardsi (scale 2 mm). 4. Lateral view, male; 5. Dorsal view, male; 6. Lateral view, female; 7. Dorsal view, female. Figures 8 – 10. Frontal view, face (scale 1 mm). 8. Citrogramma asombrosum, female; 9. Citrogramma pennardsi, male; 10. Citrogramma pennardsi, female.