Brachyxystus subsignatus Faust 1897
Creators: name: Yunakov, Nikolai
name: Korotyaev, Boris
name: Alziar, Gabriel
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Curculionidae
Brachyxystus
Brachyxystus subsignatus

description: Brachyxystus subsignatus Faust, 1897
Fig. 6
Brachyxystus subsignatus Faust, 1897: 356.
Proposed subspecies composition.
Brachyxystus subsignatus subsignatus Faust, 1897: 356.
= Polydrusus (Chaerodrys) setifrons kashmirensis Voss, 1959: 82, syn. nov.
Brachyxystus subsignatus gulmargicus Thompson, 1977: 454.
Brachyxystus subsignatus praevius (Voss, 1959), comb. nov.
Polydrusus (Chaerodrys) setifrons praevius Voss, 1959: 81
Type material.
Brachyxystus subsignatus: the lectotype was designated by Thompson (1977) who noted that he had no information about the second specimen mentioned by Faust (1897). We found the second specimen in Johannes Faust’s collection and consider it the paralectotype (Fig. 6); INDIA “ Khamba [= Chamba] / Andrewes ” [handwritten by J. Faust]; “ subsignat / us Fst. ” [handwritten by J. Faust]; “ Coll. J. Faust ” [yellow, printed]; “ Type ” [red, printed]; “ Staatl. Museum für / Tierkunde Dresden ”; MTD.
Polydrusus (Chaerodrys) setifrons kashmirensis. Holotypus ♀ (Fig. 7); “ Kashmir / Rost 1905 ”; Holotypus / Polydr. setifrons / subsp. / kashmirensis m. [red label]; Polydrusus (Chaerodrys) setifrons / E. Voss det., 1956 / subsp. n. kashmirensis; “ Coll. E. Voss / Eing. 3-75 ”; ZMH 839387.
Discussion.
Eduard Voss correctly classified his taxon within the tribe Polydrusini but made an error regarding its genus and species. Upon noticing the similarity of his Kashmiri species with the Iberian Polydrusus setifrons, Voss did not consider comparing it with Faust’s Brachyxystus subsignatus. Consequently, he mistakenly described Brachyxystus subsignatus as Polydrusus setifrons kashmirensis.
Despite some convergent similarity of general appearance, Polydrusus setifrons and Brachyxystus subsignatus differ significantly in the structure of the antennae, epistoma, prementum, maxilla, and genitalia of both sexes. Polydrusus setifrons is distinguished by the following characters: anterior margin of the epistoma with a fringe of tiny setae; maxilla (mx) not extending beyond hypostoma (hy); prementum (pr) large and broad; mandibular scar large (mn-sc) (Fig. 8 G); antennal scape thin and long, reaching midlength of occiput, as long as funicle and club combined (Fig. 8 E); stalk (me-sk) of metendosternite short, furcal arms (me-fa) bifurcate; spermatheca C-shaped, ramus vestigial (Fig. 8 D); ovipositor (Fig. 8 B, C) with styli (sty); median lobe long, narrow, and tubular, as long as apodemes; endophallus finely armed, without coarse spicules (Fig. 8 A); and recumbent round scales have rows of papillae (Fig. 8 H) between veins.
On the other hand, Brachyxystus subsignatus shows significant structural affinity in the head and genitalia of both sexes with Pachyrhinus, as thoroughly examined by Thompson (1977).
These two species also differ in host plant preferences. Unlike Brachyxystus subsignatus, which feeds on Himalayan conifers (Stebbing 1911, 1914), Polydrusus setifrons is strictly associated with Mediterranean oak forests and mixed pine-oak forests in the Iberian Peninsula. It is a known defoliator of oaks (Quercus suber and Q. ilex; Fagaceae) throughout southern Spain (Gallardo and Cárdenas 2017).
description: Published as part of Yunakov, Nikolai, Korotyaev, Boris & Alziar, Gabriel, 2024, Miscellaneous notes on the systematics of and synonymy in Entiminae (Coleoptera, Curculionidae), pp. 249-264 in Contributions to Entomology 74 (2) on pages 249-264, DOI: 10.3897/contrib.entomol.74.e136994