Phymatodes obliquus Casey, NEW STATUS
Creators: name: Swift, Ian P.
name: Ray, Ann M.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Cerambycidae
Phymatodes
Phymatodes obliquus

description: Phymatodes obliquus Casey, NEW STATUS
(Figs 26, 27)
Phymatodes obliquus Casey, 1891:26. Type locality: California, USA. USNM
Phymatodes harfordi Casey, 1912:279. Type locality: Santa Clara County, California, USA. USNM
Phymatodes decussatus var. obliquus, Hardy and Preece, 1926:28
Phymatodes decussatus var. latifasciatus Hardy and Preece, 1927:191. Type locality: Mt. Tolmie, Victoria Island, British olumbia, Canada. CNC
Phymatodes decussatus var. posticus Van Dyke, 1920:36; Linsley, 1964:51. Type locality: Camp Nelson, Tulare County,California, USA. CASC NEW SYNONYMY
Phymatodes decussatus australis Chemsak, 1963:40. Type locality: Ensanada, Baja California, Mexico. CASC NEW SYNONYMY
Phymatodes obliquus is the oldest name to replace the taxon in Linsley’s (1964) concept of P. decussatus (see the discussion of P. decussatus as well). Phymatodes obliquus can be distinguished from similar species, such as P. decussatus (as defined herein), by its non-setose white fasciae, which are arcuate, rather than angulate; the elytral pubescence, which is long, erect, golden and white in P. decussatus, and short, subappressed, and dark in P. obliquus; and the upper eye lobe, which is contiguous with the lower lobe by at least four rows of omatidia, while in P. decussatus most specimens have only a sclerotized line, lacking ommatidia.
This west coast species is similar to P. v a r i u s (Fabricius) from the eastern US, and few salient characters have been found to separate the two species. The most consistent differences are the extent of the white fasciae on the elytra, wherein P. v a r i u s possesses more expansive markings while in P. obliquus they are somewhat reduced. The basal pair is also more transverse in the former species, and more arcuate in the latter. Additionally, P. v a r i u s generally has more dense, dark setae at the elytral base, whereas in P. obliquus the setae are less dense and somewhat lighter. Both of these characters are difficult to interpret when examining a single specimen or even small series. Nevertheless, based on these minor differences, as well as the fact that the two populations appear to be allopatric, the two species are herein retained. However, future analyses may prove these taxa indistinct.
The subspecies previously assigned to P. obliquus (P. decussatus sensu Chemsak), are highly variable as has been noted by several authors (Hovore and Giesbert 1976, Swift 2008). In southern California, specimens exhibiting characters of both subspecies have been reared from the same logs, and long series from any region vary widely in form and coloration. Thus, it seems best to treat this species as a single highly variable taxon.
This species as well as P. v a r i u s, P. dimidiatus, and P. vulneratus have pronounced sexual dimorphism. The metathoracic legs are longer and more robust in males; and the pronotum is broadly rounded at the sides in males, while in the females it is feebly angulate. These four species also share similar gland pore arrays on the anterior margin and pleura of the pronotum.
Specimens examined: 326, including the types of P. obliquus, P. d. posticus, and P. d. australis
description: Published as part of Swift, Ian P. & Ray, Ann M., 2010, Nomenclatural changes in North American Phymatodes Mulsant (Coleoptera: Cerambycidae), pp. 35-52 in Zootaxa 2448 on pages 46-47, DOI: 10.5281/zenodo.294195