Achilia crassicornis Jeannel, 1962

Giorgio Sabella, Sergey A. Kurbatov & Giulio Cuccodoro, 2017, A revision of the Chilean Brachyglutini - Part 2. Revision of Achilia Reitter, 1890: A. crassicornis, A. tumidifrons, A. bifossifrons, and A. lobifera species groups (Coleoptera: Staphylinidae: Pselaphinae), Revue suisse de Zoologie 124 (1), pp. 119-140 : 120-122

Achilia crassicornis Jeannel, 1962

Figs 1-11 , 21, 24, 31

Achilia crassicornis crassicornis Jeannel, 1962: 399 , figs 144 (habitus) and 146 (aedeagus). ‒ Franz, 1996: 114, fig. 61 (aedeagus).

Achilia crassicornis antarctica Jeannel, 1962: 399 , fig. 145 (ae- deagus). ‒ Franz, 1996: 114 syn. nov.

Achilia obscura Jeannel, 1962: 401 syn. nov.

Type material (41 ex.): SOUTHERN CHILI: Región Magallanes y de la Antártica Chilena: Antártica Chilena prov.: MHNS; 1 ♂ (holotype of Achilia crassicornis antarctica n° 1623); Navarino Island, Puerto Williams; 31.I.1957; G. Kuschel. – MNHN; 12 ♂ and 18 ♀ (paratypes of Achilia crassicornis antarctica ); Navarino Island, Puerto Williams; 54° 56’S; 31.I.1957; G. Kuschel; Nothofagus betuloides and Nothofagus pumilio forest. – Última Esperanza prov.: MHNS; 1 ♂ (holotype of Achilia crassicornis crassicornis n° 1575); Puerto Eden; 06.XII.1958; G. Kuschel. – MNHN; 6 ♂ and 2 ♀ (paratypes of Achilia crassicornis crassicornis ); Wellington Island, Puerto Eden, Carlos Islet; 49° 09’S; 06.XII.1958; G. Kuschel; Nothofagus betuloides dense forest. – MNHN; 1 ♀ (holotype of Achilia obscura ; according to the original description the holotype of A. obscura should have been deposited in MHNS, however we found it in MNHN); Wellington Island, Puerto Eden, Carlos Islet; 49° 09’S; 600 m; 6.XII.1958; Nothofagus betuloides forest.

Additional material (2166 ex.): See Appendix 1.

Description: Body 1.50-1.75 mm long, reddish brown with head and abdomen sometimes slightly darker and palpi yellowish. Pubescence decumbent with dense and long setae, uniform on entire body. Head wider than long; frontal lobe short with rounded sides; surface smooth, shiny, with some minute punctures; vertexal sulcus deeply impressed and narrowed in middle; vertexal foveae shallow and large; eyes protruding, longer than convex temples. Pronotum wider than long and wider than head; posterior portion of lateral outlines sinuate; disc smoothly convex, shiny, with some small punctures; basal margin bordered with row of contiguous shallow impressions; median antebasal fovea smaller than lateral foveae. Elytra together wider than long with protruding humeri; disc smooth, shiny, with some small punctures; generally four basal foveae (two lateral foveae very close) or occasionally three (lateral foveae consisting of two combined foveae); sutural stria entire; discal stria extending to about elytral midlength. Legs slender. Abdomen smooth, shiny, with some minute punctures; tergite I with basal striae slightly diverging, extending to about one-third of paratergal length, separated at base by about onethird of tergal width, with short and sparse setal brush between striae.

Male: Head as in Figs 21 & 24, with occiput strongly convex. Antennae ( Fig. 11 ) with scape distinctly longer than wide; pedicel slightly longer than wide; antennomeres III-VIII small and slightly tranverse; antennomere IX strongly transverse with protruding mesal margin; antennomere X strongly thickened, wider and longer than XI, medial side truncate with broad subtriangular fairly flat area entirely delimited by sharp low ridge and covered with short dense pubescence. Metasternum convex; ventral margin of mesotrochanters with small acute lateral spine; all tibiae unarmed. Abdominal tergites unmodified; ventrites IV-V slightly flattened at middle. Aedeagus ( Figs 1-2 ) 0.39- 0.41 mm long; dorsal plate ovoid with rounded sides and diverging dorsal strips starting from middle of dorsal plate; copulatory pieces each divided into two simple or bifurcated spreading branches slightly variable in shape ( Figs 1-10 ). Parameres with outer outline only slightly convex or fairly straigth at level of middle seta; tips narrow recurved internally.

Female: Similar to male except: head with occiput broadly convex, not swollen; antennomeres X and XI less wide than in male, X with medial side not truncate and shorter than XI; mesotrochanters and abdominal ventrites unmodified.

Collecting data: Collected from September to March, mainly in Nothophagus forests, but also in Araucaria , Saxegothaea conspicua and Fitzroya cupressoides forests, where it was found in remnants of forests or at their edges at elevations ranging from sea level up to 1500 m and the treeline. Most specimens came from sifted samples of leaf and log litter, moss, dead trunks, vegetable debris, and sometimes mushrooms, but other collecting techniques include car netting, flight intercept (window) traps, malaise traps, carrion traps, pan traps, and screen sweeping. Jeannel (1962) mentions specimens collected wandering on the sandy shores of Lacar Lake (Argentina, Neuquén province).

Distribution: Achilia crassicornis is distributed ( Fig. 31 ) from the southernmost regions of Chile and Argentina to Central Chile (northernmost province: Ñuble) and Central Western Argentina (northernmost province: Neuquén). Records from Chepu (Chiloé prov.) come from Jeannel (1962). According to Jeannel (1962) it is the only species of Achilia to be so widespread in the Valdivian and Magellanes forests.

Comments: The holotype and only known specimen of A. obscura should be in the MHNS collection according to Jeannel (1962: 401, but it is in the MNHN collection. Moreover, in the catalog of the MHNS holotypes of insects ( Camousseight, 1980) this taxon is not mentioned. Jeannel (1962) described A. antarctica as a subspecies of A. crassicornis that was characterized by having the pronotum barely transverse, the aedeagus larger with shorter paramere apices, and the internal sac with stouter copulatory pieces. He also described the new species A. obscura to accomodate specimens differing from A. crassicornis by having the body darker and slightly longer, as well as the basal striae of abdominal tergite I more narrowed. However, after examining abundant materials we concluded that these differences were overestimated and pertain to intraspecific variation, and consequently place here both A. crassicornis antarctica Jeannel, 1962 and A. obscura Jeannel, 1962 as junior synonyms of A. crassicornis Jeannel, 1962 (syn. nov.).

Two males from Chiloé Island (San Pedro and Cucao) have the antennomeres X narrower with their medial side not truncate, but their aedeagi are similar to that of the other males of A. crassicornis that we examined, and the shape of their copulatory pieces ( Figs 8-9 ) fall within the range of intraspecific variation that we observed for this structure.

Figures

Fig. 31. Distribution map of Achilia crassicornis (excluding Argentina) based on examined material.

Figs 1 - 10. Aedeagi (1 - 2) and variability of the internal sac (3 - 10) of Achilia crassicornis. (1) A. crassicornis crassicornis, paratype from Puerto Eden, Última Esperanza province. (2) A. crassicornis antarctica, paratype from Puerto Williams, Antártica Chilena province. (3) specimen from Cerro Castillo Natural Reserve, Coihaique province. (4) specimen from Ushuaia Mount San Martial, Tierra del Fuego province. (5) specimen from Aguas Calientes to Antillanca, Osorno province. (6) specimen from Playa Linda, Cautín province. (7) specimen from Conquillo National Park, Cautín province. (8) specimen from San Pedro, Chiloé province. (9) specimen from Cucao, Chiloé province. (10) specimen from Chiloé National Park, Chiloé province.

Figs 11 - 13. Male antennae of Achilia. (11) A. crassicornis.