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Chiasognathus beneshi

Chiasognathus beneshi Lacroix, 1978

Authors: M.J. Paulsen, Andrew B.T. Smith.

Chiasognathus beneshi Lacroix, 1978: 250. Type material: Holotype reportedly deposited in the J. P. Lacroix collection. Lacroix is deceased, and the Lacroix collection is not available for study and is in an unknown state of preservation. Type locality: “Chili, Province d’Aysen: Río Manihuales”.

Description. Length: 21.7–28.0 mm. Width: 10.0–12.6 mm. Color: Reddish brown with weak green or purple metallic reflections. Head: Form subquadrate. Surface punctate; punctures fine to coarse, generally setose with short to long setae. Anterior margin of head rounded or concave, not strongly produced beyond anterior angles, lacking median nasus. Anterior angles obtusely rounded in dorsal view. Male mandibles cylindrical, 1.5–2× as long as head, externally almost straight until internally curved apex. Dentate carina beginning with basal tooth on dorsal surface, continuing along internal edge, not becoming internal; dorsal and ventral teeth present either side of apex resulting in scoop-like appearance; apex lacking patch of setae. Base of mandibles lacking ventral tooth. Female mandible externally rounded in basal third, dorsally flattened, with median internal tooth. Galeal brush moderately long, 2× longer than mentum. Antennal scape with sparse area of long setae present in males, or setae absent. Pronotum: Posterior and lateral angles den- tate, posterior angle more strongly so in males, or angles obsolete. Lateral margins distinct, crenulate. Dorsal surface with transverse ridge, longitudinal median fur- row broad, weak depressions indicated either side of disc before middle in most specimens. Surface near margins with distinct, moderately long setae in females, glabrous in males examined. Elytra: Surface weakly shiny, appearing wrinkled, densely punctate, setose; setae scale-like, often abraded except on lateral elytral declivity; females lacking distinct, scattered, longer bristle-like setae. Apex rounded, lacking spine. Epipleuron flat. Legs: Protibiae short, serrate externally; ventral surface along internal margin with 2–5 small teeth. Male genitalia: Flagellum moderately long, subequal in length to basal piece.

Distribution. Specimens were examined only from Aisén, Chile. CHILE (6): Aisén (6): Caleta Tortel, Coihaique, Lago Yulton, Río Correntoso.

Temporal distribution. January (3), February (3).

Diagnosis. This species, although externally nondescript, can be separated from the C. latreillei complex by the longer flagellum of the male genitalia and by its geographic distribution.

Remarks. The amateur entomologist J. P. Lacroix described this species. Most taxa named by Lacroix, especially in the Chiasognathini, are now considered synonyms, including eight of twelve available Lacroix names in Sphaenognathus (Chalumeau and Brochier 2007; Paulsen 2008). The type specimen was not deposited in an institution and is unavailable for study, but we have examined specimens from near the type lo- cality in Aisén that display mandibles identical to those drawn for the holotype of C. beneshi. These specimens have a distinctly longer flagellum of the male genitalia than do C. latreillei. Because this character appears to be useful in separating other species in the genus, we have refrained from synonymizing C. beneshi at this time. However, externally there are few strong morphological characters to support the distinction, in part because the C. latreillei complex is so variable and possibly composed of multiple taxa. The median teeth of the male mandibles in C. latreillei generally point distinctly inward, while in the C. beneshi material studied the teeth remain more or less vertical. The apex of the male mandible in C. beneshi generally has a strong tooth above and below the apex, giving a scoop-like appearance, and the mandibles overall are more cylindrical and curved internally at the apex. Most specimens of C. latreillei have ex- ternally straighter mandibles with a simple apex. Unfortunately, a few specimens of the C. latreillei complex have mandibles similar to those of C. beneshi. The specimens treated as C. beneshi by some authors (Mizunuma and Nagai 2001; Chalumeau and Brochier 2007) represent an undescribed species that we describe below. Chiasognathus beneshi was previously recorded from Biobío (Las Trancas) but this locality is erroneous due to the misapplication of the name – this species is only known to occur in Aisén region of Chile.

Location: Chile; BioBio, Nuble, Las Trancas
Max. size: 32mm
Collection: Capt. Philippe Bourdon