Cerodontha (Xenophytomyza) illinoensis (Malloch)

Boucher, Stéphanie, 2003, The New World species of Cerodontha (Xenophytomyza) Frey (Diptera: Agromyzidae), Zootaxa 178, pp. 1-8 : 6-7

Cerodontha (Xenophytomyza) illinoensis (Malloch) (Figs. 4–6, 8)

Agromyza illinoensis Malloch, 1934: 483 .

Cerodontha (Xenophytomyza) illinoensis: Frick 1952: 151 . Cerodontha (Poemyza) simcoensis Spencer, 1969: 135 .

Recognition.­ Cerodontha (Xenophytomyza) illinoensis is externally very similar to C. (X.) biseta . Following Malloch’s (1934) brief original description, this species was redescribed and/or illustrated by Frick (1952) and Spencer and Steyskal (1986). Spencer (1969) described Cerodontha (Poemyza) simcoensis from Ontario but later synonymized it with C. (X.) illinoensis ( Spencer & Steyskal 1986) .

Frick (1952) distinguished C. (X.) illinoensis from C. (X.) biseta by the paler coloration, the third antennal segment having a more pronounced angle and the genovertical plates raised above the eye margins, but these characters are not consistent among the specimens examined and could not be used in the key.

Distribution.­ Cerodontha (X.) illinoensis is so far restricted to the northeastern Nearctic region. It appears that this species is not as commonly collected as C. (X.) biseta in North America; it is known from only four localities ( Fig. 8 ) and, apparently, no confirmed specimens have been collected since 1952.

Host plants.­ The host plant of C. (X.) illinoensis is unknown but, given the known host plants of other species of the subgenus, it is probably in the Poaceae .

Remarks.­ Malloch’s original description of Agromyza illinoensis was a brief mention in the introduction to a paper on Neotropical Agromyzidae ( Malloch 1934) , but he included enough characters to distinguish it from other North American species and thus his description was valid ( Frick 1952). Although Malloch did not record any type material in his publication, he had labeled one specimen in the INHS as “ type ” and two others in the NMNH as paratypes ( Frick 1952). Frick considered the specimen labeled “ type ” to be the holotype, and the other two labeled specimens as well as eight other specimens collected at the same locality in the same month to be paratypes. Frick (1952) designated the “ type ” specimen as a neotype (this may have been an error for “ lectotype ”) and designated Malloch’s two labeled paratypes and the eight additional paratypes as “neoallotype” and “neoparatypes”. However, according to the International Code of Zoological Nomenclature (ICZN 1999) Malloch’s original description did not explicitly designate type specimens and the description was apparently based on multiple specimens, so all of Malloch’s specimens should be considered syntypes (ICZN Article 73.1, Recommendation 74F) and Frick’s (1952) designation of a neotype was invalid because the syntype series was still in existence (ICZN Article 75.1). Because the identity of this species is not in doubt, I have chosen not to designate a lectotype.

Type material ( Cerodontha illinoensis ).­ Syntypes: UNITED STATES: Illinois: White Heath, 22.v.1915 (3F); same except 8.v.1915 (1M, 1F), same except 9.v.1915 (2M), same except 16.v.1915 (2F), same except 30.v.1915 (2F) (INHS, NMNH).

Type material ( Cerodontha simcoensis ).­ Holotype M: CANADA: Ontario: Simcoe, 9.vi.1939, G.E. Shewell (CNC). Paratypes: same data as holotype (2M, 1F, CNC) (two other female paratypes are not conspecific).

Other material.­ UNITED STATES: Illinois: White Heath, 2.vi.1917 (2M, 2F, INHS) 3.vi.1917 (4M, 4F, INHS); Tennessee: East Ridge, Hamilton Co. 5.v.1952, G. Peck (2M, CNC, not examined); Virginia: Maywood, Alexandria Co, 4.vi.1922 (2M, 1F, NMNH).

Figures

FIGURES 7 – 8. New World distribution of 7, Cerodontha (Xenophytomyza) biseta; 8, Cerodontha (Xenophytomyza) illinoensis (solid circles ­ specimens examined; open circle – published record, not examined).