Revision of the Dysmorphoptilidae (Hemiptera: Cicadomorpha: Prosboloidea) of the Queensland Triassic—Part 2
Creators: name: Lambkin, Kevin J.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy

description: Trifidella Evans, 1956
Trifidella Evans, 1956: 215–216.
Type species. Trifidella perfecta Evans, 1956, by original designation.
Alotrifidus Evans, 1956: 216. Syn nov.
Type species. Alotrifidus interruptus Evans, 1956: 216, fig.16D, by original designation.
Diagnostic characters. Tegmen small, no more than 9 mm long; gently emarginate at apex at RA; anterior margin fairly straight; precostal carina and marginal membrane quite distinct; hypocostal carina short; coarsely punctate, somewhat coarser still in basal costal space; strigil not detected in basal costal space; hyposubcostal carina short, strongly concave; clavus not preserved; primary fork of R at about clavus ½ length; primary fork of RA proximal to apex of clavus, at level of CuA fork; RA1 stem long, running to apical margin, with 2 or 3 anteriorly-directed pectinate branches, the first deeply forked in QM F6504a/b; RA2 occupying a small area apically, forked just before apex of RA1, with 2 branches curved anteriad; RA2 and RP joined by a crossvein; RP simple or with a terminal fork; M1+2 simple or with a terminal fork; M3+4 with a terminal fork; M with a short, slightly obliquelyangled basal piece, then fused with CuA for a considerable distance up to the level of first costal veinlet; apical mcu upright; CuA1 strongly convex; CuA2 nearly straight, not much shorter than CuA1.
Notes. Trifidella is a classic dysmorphoptilid, with its emargination at RA1, coarse punctation, RA1 entering the margin antero-apically, and RA2 entering the margin apically and of limited extent. Evans’ figure of the holotype of the type species shows RA2 with three branches. Very careful examination of the specimen, however, demonstrates that there are indeed only two branches as there are in all other specimens of the species. The peculiar short basal piece of M and its fusion for some distance with CuA is considered as the apomorphy for the genus. It may be the sister of the Queensland Dysmorphoptiloides Evans which also has a similar fusion of M and CuA although over a much shorter distance and with a more oblique basal piece (Lambkin 2015). Trifidella differs from Dysmorphoptiloides, however, in having RA and RP joined by a crossvein rather than fused.
Evans (1956, p.216) noted that Alotrifidus differed from Trifidella “in the [arched] shape of the costal margin and in the [more distal] position of the point of departure of Rs [RP] from R”. Alotrifidus was based solely on the holotype of its type species, A. interruptus, which on examination turns out to be simply another specimen of T. perfecta. Evans’ figure and the photograph in Jell (2004, p. 36) give a false impression of the specimen which is fragmentary and deformed on the rock surface. The punctation of the costal space is more clearly preserved than in the holotype of T. perfecta but is no more coarse; the basal costal margin is curved downwards on the rock surface giving the appearance of being arched; the distal costal space is incomplete and steeply sloped on the rock surface making it appear artificially narrow and the costal veinlets artificially short; and the apical ⅓ of the tegmen is missing. The only real differences between the holotype of A. interruptus and the holotype of T. perfecta are that the base of RP is more upright than inclined, thus making it slightly more distally placed, and one of the costal veinlets is forked. I consider these as no more than minor intra-specific variations and not the basis of a separate taxon.
description: Published as part of Lambkin, Kevin J., 2016, Revision of the Dysmorphoptilidae (Hemiptera: Cicadomorpha: Prosboloidea) of the Queensland Triassic — Part 2, pp. 207-218 in Zootaxa 4092 (2) on pages 213-215, DOI: 10.11646/zootaxa.4092.2.4, http://zenodo.org/record/267859