Apterodorcus tristis

E, José Mondaca, 2008, Revision of the genus Apterodorcus Arrow (Coleoptera: Lucanidae: Lucaninae) of southern South America, Zootaxa 1922, pp. 21-32 : 30-31

Apterodorcus tristis (Deyrolle in Parry, 1870)

( Figs. 1 , 3, 5 , 7 , 9, 11 )

Apterodorcus tristis (Deyrolle in Parry, 1870). Holotype (MNHN) examined, labeled: a) black bordered “Ex Museo / Mniszech”; b) handwritten “= Apterodorcus / bacchus Westw. (sic) / det. Weinreich”; c) red paper, “ Sclerostomus tristis male symbol / Deyrolle in Parry, 1870 / HOLOTYPE / Det. M.J. Paulsen 2008”.

Sclerostomus tristis Deyrolle in Parry, 1870: 95. (original combination).

Description. Males ( Fig. 3 ) n=24. Females ( Fig. 5 ) n= 18. Length: 19.2 – 33.0 mm. Width: 9.0 – 14.4 mm. Color: Dorsal surface opaque black. Vestiture: Apparently glabrous dorsally. Head: Canthus rounded. Both sexes with temporal process; process truncate externally in male majors, subtrapezoidal ( Fig. 3 ). Male majors with mandibles ( Fig. 7 a) as long as head, curved before apex, apices strongly bifurcate with teeth acute; internally near middle with 4 obtuse teeth; dorsally with strong carina parallel with a longitudinal subcarinate tooth; tooth not coplanar with dorsal surface. Moderately developed males and male minors with mandibles ( Figs. 7 b, 7c) shorter than head, curved to apex, apex strongly bifurcate with teeth acute; internally near middle with 3–4 obtuse teeth; dorsally lacking carina but with longitudinal tooth or gibbosity on internal face; tooth or gibbosity not coplanar with dorsal surface. Female mandibles ( Fig. 7 d) as in A. bacchus , but concave dorsally with exterior margin subcarinate, produced externally at base. Pronotum: Form convex, broader, shorter than in A. bacchus . Anterior angle weakly produced, sides parallel (slightly constricted medially) to angulation in basal third, sinuate from angulation to posterior angle. Margins beaded (bead obsolete anteromedially), weakly shining; anterior margin not bituberculate in either sex. Surface punctate; punctures fine to moderate on disc, becoming larger along midline, larger and coalescent near margins. Anterior margin with distinct row of orange setae of uniform length. Posterior dorsal margin with distinct field of orange setae visible in dorsal view. Scutellum: Form subtriangular, occasionally depressed below level of elytra. Elytra: Form convex, punctate; punctures fine on disc, becoming larger and coalescing laterally and basally. Wings: Brachypterous in both sexes ( Fig. 9 ). Legs: Mesotibiae and metatibiae with large external tooth, 0–1 smaller teeth proximally. Male Genitalia: Form simple ( Fig. 11 ), overall more slender, but not clearly distinguishable from that of A. bacchus . Female Genitalia: Genitalia indistinguishable from A. bacchus .

Diagnosis. This species is distinguished from A. bacchus by its strongly opaque dorsal surface, striking band of uniform orange setae along the anterior pronotal margin and field of orange setae along the posterior margin, different form of the male mandibles which are dorsally carinate or have a smaller internal tooth removed from the dorsal surface, and pronotum lacking two anterior tubercles in females.

Distribution ( Fig. 1 ). Central Chile, in the Cordillera de la Costa south of Santiago to near Rancagua.

Locality data. 43 specimens examined from FMNH, JMEC, MGGC, MJPC, MNHN, MNNC.

CHILE (39): Región Metropolitana de Santiago (28): Alhue (5); Alto Cantillana (8); La Ollita (2); Pichi Alhue (13). VI Región del Libertador B. O’Higgins (15): Doñihue, Cerro Poqui (1); Lo Miranda (Roblería Llivi-Llivi, Portezuelo) (13). No data (1).

Temporal data. January (1), November (13), December (26). No data (3).

Remarks. The vast majority of Apterodorcus specimens in collections belong to the common A. bacchus , and the status of this second species has been unclear since its description; subsequently it was considered a synonym of A. bacchus by Benesh (1960). Upon examination of the Deyrolle type specimen from MNHN, we determined that A. tristis was a valid species distinct from A. bacchus . However, in hundreds of specimens of Apterodorcus examined none possessed the characters present in Deyrolle’s holotype, and the only provenance available for that specimen indicated “ Chili ”. Fortunately, we subsequently located several specimens in the JMEC that did agree with A. tristis , providing the locality information below. Additional material has since been located in a few institutions and private collections.

This species is the northern most lucanid in Chile, being found in the Cordillera de la Costa in central Chile just south of Santiago. Specimens have been collected walking during the day in the roble ( Nothofagus macrocarpa ) forest and in pitfall traps. Additional collecting in the area may increase the range of this species even farther to the north. The only other lucanid known from this area is the flightless species Sclerostomus (Sclerostomulus) nitidus Benesh , which is known from only a handful of specimens (see Paulsen 2005) and is restricted to the same relictual forests. The nearest known populations of A. bacchus occur approximately 90 km to the south.

Figures

FIGURE 1. Distribution of Apterodorcus species: A. bacchus (circles), and A. tristis (triangles). Regions of Chile indicated by Roman numeral, provinces of Argentina by postal code (Q = Neuquén, U = Chubut, R = Río Negro).

FIGURES 2 – 5. Dorsal habitus of Apterodorcus species: 2) A. bacchus, major male; 3) A. tristis, major male; 4) A. bacchus, female; 5) A. tristis, female.

FIGURES 6 – 7. Mandibular development in 6) Apterodorcus bacchus and 7) A. tristis, shown for each species: a) major male, b) moderately developed male, c) minor male, d) female.

FIGURES 8 – 11. Wings and male genitalia of Apterodorcus species: 8) Brachypterous right wing of A. bacchus male; 9) Brachypterous right wing of A. tristis male, with right elytron for scale. 10) Male genitalia of A. bacchus; 11) Male genitalia of A. tristis. Scale bars indicate 1 mm.