Citrogramma
Citrogramma Vockeroth, 1969.
Vockeroth, J.R. (1969). A revision of the genera of the Syrphini (Diptera: Syrphidae). Memoirs of the Entomological Society of Canada 62: 176 pp.
Citrogramma Vockeroth, 1969.
Vockeroth, J.R. (1969). A revision of the genera of the Syrphini (Diptera: Syrphidae). Memoirs of the Entomological Society of Canada 62: 176 pp.
Vockeroth (1969) did not indicate the gender of Citrogramma, but he used a neuter form for species epithet of his new species, e.g. bicornutum, notiale, quadricornutum and sedlacekorum. Vockeroth also changed the species epithet of the previously described species without neuter termination, i.e. clarum, difficile and variscutatum. According to article 30.2.3 of the International Code of Zoological Nomenclature (ICZN, 1999), Citrogramma must therefore be treated as of neuter gender.
The genus Citrogramma is recognized among the syrphines (subfamily Syrphinae, tribe Syrphini) by the following combination of characters: 1) scutum with lateral broad yellow vitta; 2) metasternum pilose (except Citrogramma quadricornutum); 3) abdomen margined; 4) scutum black with medial brown or olivaceous pollinosity, usually with submetallic area divided into vittae or not; and 5) subscutellar fringe present.
Rather small to large, slender to robust species.
Head. Face with tubercle, gradually sloping dorsally, more abrupt ventrally, pilose; mouthparts normal; eye bare; male holoptic; antenna short, shorter than face; basoflagellomere short, roundish to oval; ocellar triangle equilateral; occiput densely pilose.
Thorax. Scutum with broad, complete bright yellow lateral margin; disc black with fine brownish/bluish sub shining pollinosity, sometimes also with shining bluish medial and/or submedial vittae or (perhaps only in slightly wetted specimens) entirely opaque black. Postpronotum bare. Scutellum simple with dark subscutellar fringe. Metasternum pilose with some long pile, bare only in Citrogramma quadricornutum Vockeroth. Wing: usually entirely microtrichose, partly bare basally in some species; vein R4+5 straight, without appendix; crossvein r-m basal; vein M1 sinuate, processive; vein M2 present, short. Alula normal, broad, microtrichose. Legs: normal, not modified.
Abdomen. Usually elongate oval, parallel-sided; slightly margined from middle of tergum 2 to end of tergum 5, but sometimes with margin greatly reduced, e.g. in C. quadricornutum present only on tergum 5; 3rd and 4th terga with an entire subbasal yellow fascia. Male genitalia. Very variable.
The most problematic genus related with Citrogramma, in terms of difficulty to correctly separate from, has been Xanthogramma Schiner, 1860. Most of the old studied specimens of Citrogramma were identified as Xanthogramma due to their external morphological resemblance. Vockeroth (1969) could not find a unique character to separate them, so that Citrogramma appeared several times in his key. Below, the main differences found between Xanthogramma and Citrogramma are listed:
1) subscutellar fringe: present in Citrogramma and absent in Xanthogramma.
2) metasternum pilosity: Xanthogramma has metasternum bare and Citrogramma has it pilose (exception in C. quadricornutum).
3) facial profile: Xanthogramma has antennal base more prominent than oral apex, while Citrogramma has oral apex more prominent than antennal base in lateral view.
4) lateral mesonotal vitta: in Xanthogramma, the lateral mesonotal yellow vitta does not reach the scutellum, or the yellow area of the scutellum, and the scutellum is bicoloured with a black fascia on the basal part and a yellow distal portion. Citrogramma has a lateral yellow vitta from postpronotum to scutellum joined with the yellow area of the scutellum. In Citrogramma, the scutellum is yellow and may or may not have a medial black macula, which never interrupts the continuity of the lateral yellow vitta as in Xanthogramma.
5) sternum 9: Citrogramma has a greatly reduced sternum 9 in most species, but Xanthogramma has normal sternum 9 in size.
Only one prey species has been cited for Citrogramma, the brown citrus aphid or Toxoptera citricida (Kirkaldy, 1907) (Hemiptera: Aphididae) (Michaud, 1999). This citation, however, is a mistaken assumption, as also suggested by Rojo et al. (2003), because C. citrinum cited as Syrphus citrinum (Brunetti, 1923) is not found in Florida (USA) from where Michaud documented the record. The voucher specimen for this record was examined by Mengual (2011) and it did not belong to Citrogramma.
Citrogramma is found in Oriental (Indomalayan) and Australasian biotic regions, crossing Wallace’s line, and in the southern provinces of China.
Specimens are reported from Nepal, India, Sri Lanka, Myanmar, Thailand, Malaysia, Vietnam, Laos, Taiwan, Indonesia, Philippines, China (Tibet [Xizang], Yunnan, Fujian, Sichuan, Hainan), Papua New Guinea (PNG), Solomon Islands, New Caledonia and Australia (Mengual 2011).
A reared female of Citrogramma notiale, found on Ageratum houstonianum Mill. (Asteraceae) in Samsonvale (Australia, Queensland), was studied and to my knowledge it is the only Citrogramma puparium known (see figs 124–126). Finally, in the original description of Citrogramma notiale, Vockeroth (1969) cited a paratype female from Sydney (Australia, New South Wales) collected by McIvor in tunnels of Bostrychopsis jesuita (Fabricius, 1775) (Coleoptera: Bostrichidae), in a wasp’s nest. But so far, nothing is clearly known of the biology of these flower flies.
A specimen of C. amarilla Mengual sp. nov. from Shillong (Meghalaya, India) has a label with the annotation “Found resting on Pine with aphid attack”. This note suggests that some species could be aphidophagous. A female specimen of C. notiale was collected “among Araucaria cunninghamii”. There are also two specimens of C. circumdatum collected from a logging area (Bulolo, Papua New Guinea) with the note:“Castanopsis/Bamboo forest”, and four species with individuals collected in “moss forest”: C. difficile, C. fascipleurum, C. hervebazini and C. vockerothi.