Cerodontha (Butomomyza) subangulata (Malloch)

Lonsdale, Owen, 2021, Manual of North American Agromyzidae (Diptera, Schizophora), with revision of the fauna of the " Delmarva " states, ZooKeys 1051, pp. 1-481 : 1

Cerodontha (Butomomyza) subangulata (Malloch)

Figs 503-507

Agromyza subangulata Malloch, 1916: 51.

Phytobia ( Poëmyza) Phytobia subangulata . Frick, 1952a: 392, 1959: 382; Spencer and Steyskal 1986b: 100.

Description

(NC male). As described for Cerodontha (Butomomyza) angulata , except as follows. Wing length 2.6 mm (♂). Female unknown. Length of ultimate section of vein M4 divided by penultimate section: 1.1. Eye height divided by gena height: 11.9. Acrostichal seta well-developed; acrostichal setulae in six straight rows. Frons between fronto-orbital plates rougher, pitted. Setae dark brown; frons darker brown, but dark brown pigment only present on tubercle; remainder of head brown to dark brown with clypeus, palpus and back of head clearly darker; brown pigment on remainder of body darker, contrasting more with paler regions; colour of postpronotum and notopleuron blotchier, with anterior and posterior regions of notopleuron yellower; wing veins brown to light brown, only yellow basal to basal cells; apices of all femora distinctly yellow, base and apex of fore tibia yellowish, and tarsi brownish yellow with apical one or two segments darker. Sclerotized portion of paraphallus flatter, band-like; distiphallus relatively straight, especially on distal 2/3, and with apex not swollen (Fig. 503 ); paired tubules of distiphallus very closely held along length.

Variation: The Illinois holotype, based on the original description, differs as follows: additional ors present, possibly up to eight rows of acrostichal setulae, eye ~ 8 × higher than gena, palpus yellowish apically, apices of mid and hind femora not yellow; additionally, the length of vein dm-m is the same as the distance from vein r-m; distiphallus slightly more curved with apex slightly swollen (Figs 504-507 ).

Host.

Unknown.

Distribution.

USA: IL. Possibly MD, NC.

Type material.

Holotype: USA. IL: St. Joseph, 3.v.1914, Hart and Malloch (1♂, INHS). [Not examined]

Additional material examined.

USA. NC: Haywood Co., Pisgah Nat. Forest , Chestnut Bald, 5900', 2.viii.1957, J.G. Chillcott (1♂, CNC) .

Comments.

The Maryland male from Cabin John (Spencer and Steyskal 1986) and the North Carolina male examined and illustrated here, were both identified as Cerodontha "near angulata" by Spencer, and tentatively assigned to Cerodontha subangulata . Compared to the holotype, the tubules of the distiphallus of these males are more slender and shallowly curved. Since the length of crossvein dm-m is shorter than the length of this vein from r-m, as seen in C. angulata , this character is no longer considered diagnostically valuable. The collection of additional material is essential to properly establishing species boundaries and morphological variation, which will hopefully supply additional characters to use in the identification key.

Figures

Figures 503 - 507. 503 Cerodontha (Butomomyza) subangulata (Malloch), phallus, ventral, non-type from North Carolina 504 - 507 C. (B.) subangulata, illustrations from Spencer and Steyskal (1986 b) 504 holotype phallus, left lateral 505 holotype phallus, ventral 506 holotype external genitalia 507 male from Cabin John Creek (Maryland), phallus, left lateral.