Chiasognathus grantii Stephens, 1831

Paulsen, M. J. & Smith, Andrew, 2010, Revision of the genus Chiasognathus Stephens of southern South America with the description of a new species (Coleoptera, Lucanidae, Lucaninae, Chiasognathini), ZooKeys 43 (43), pp. 33-63 : 44-48

Chiasognathus grantii Stephens, 1831

Figs 1–3, 14–15, 28

Chiasognathus grantii Stephens, 1831: 214 . Type material: holotype male (CUMZ) labeled a) red label “ Chiasognathus / grantii Stephens, 1831 / HOLOTYPE [male symbol] / Det: M.J. Paulsen & A.B.T. Smith”. Type locality: “Island of Chiloe.”

Tetropthalma chiloensis Lesson, 1833 : plate 24. Type material: lectotype designated by Chalumeau and Brochier (2007) using the original illustration in Lesson (1833) under ICZN Article 74.4. The original specimen could not be located in the MNHN and has presumably been lost. Type locality: “l’île de Chiloë.”

Chiasognathus affinis R. Philippi in F. Philippi, 1859: 658. Type material: Lectotype male (MNNC) designated by Chalumeau and Brochier (1995) labeled a) handwritten “ Chiasognathus / affinis Phil. ”; b) orange label “ LECTOTYPE ”; c) handwritten “ Chiasognathus / affinis Phil. / det F. Chalumeau / & B. Brochier ‘94”; d) Chiasognathus grantii / Stephens / Dét. det F. Chalumeau / & B. Brochier ‘94”; e) red label “ Chiasognathus / affinis / Philippi [male symbol] / LECTOTYPE / A.B.T. Smith”; f) “ Chiasognathus / grantii / Stephens, 1831 / det. M.J. Paulsen 2010”. Type locality: “cerca del Corral.”

Chiasognathus pygmaeus Dallas, 1933: 74 . Type material: Holotype lost – reportedly deposited in the Dallas collection ( Dallas 1933). Primary types should be deposit- ed in legitimate institutional collections so they have a good chance of being available for study by taxonomists. Neotype male, (MNNC) HERE DESIGNATED, labeled a) handwritten “ Aysen / I-37”; b) “[‘95] / Chiasognathus grantii / Stephens / Dét. Chalumeau & B. Brochier / [ var. pygmaea ]”; c) red label “ Chiasognathus / pygmaeus Dallas male symbol / NEOTYPE / Paulsen & Smith”; d) “ Chiasognathus / grantii / Stephens, 1831 / det. M.J. Paulsen 2010”. A neotype is designated in order to preserve the stability of nomenclature by selecting one specimen as the sole, name-bearing type of this taxon because the original name-bearing type specimen(s) was lost or destroyed. The neotype specimen serves to tie the published name to an actual specimen and as a reference standard for the taxon. This is important because there has been confusion in the literature regarding this name with disagreement whether it is a valid species, synonym of C. grantii , or synonym of C. latreillei . Type locality: “ Chile ”.

Description. Length: 24.5–88.0 mm. Width: 9.5–17.0 mm. Color: Light to dark reddish brown, everywhere with green, gold, or purple metallic reflections. Pronotum with metallic coloration gold/green on disk, becoming purple near margins, lateral fovea darker bluish-green. Elytra with disc greenish-brown due to weak green and purple metallic reflections, lateral margin darker metallic green. Head: Form subquadrate in minor males and females, subtriangular in major males. Surface punctate; punctures fine to coarse, generally setose with short to long setae. Anterior margin of head produced beyond anterior angles and always with median nasus, nasus variably binodose or simply obtuse. Anterior angles produced ventrally, acute in dorsal view. Male mandibles 2–6× as long as head, externally sinuate, arched and somewhat flattened in lateral view; dentate carina internally on dorsal margin for entire length of mandible; teeth variable along mandible, large basal tooth followed by serrate margin in basal third and more widely spaced, peg-like teeth in apical two-thirds. Apex abruptly curved, distally acute and hooked upwards in male majors, male majors with patch of setae inside apex. Base of mandibles with large, ventral tooth always present, in male majors longer than head; tooth internally serrate. Female mandible externally rounded, never with median internal tooth, but with strongly produced internal carina ventrally near base. Galeal brush elongate, 2–3× longer than mentum. Antennal scape with well-developed area of long setae present at apex in males. Pronotum: Posterior angle and lateral angle strongly dentate, especially in males; posterior angle uncinate and somewhat curved anteriorly in major males. Lateral margins distinct, weakly crenulate. Dorsal surface not strongly ridged, longitudinal median furrow distinct basally. Elytra: Surface shiny, appearing smooth, actually densely punctate, setose; setae scale-like, microscopic, often broken off. Apex spinose with acute spine. Epipleuron flat. Legs: Protibiae elongate, dentate externally; ventral surface along internal margin with teeth well developed.

Figures Ι4–Ι5. Dorsal habitus of C. grantii . Ι 4 male, and Ι 5 female.

Male genitalia: Flagellum long, length more than 2× length of parameres and basal piece together (Fig. 3).

Distribution. This species is found in central Chile and neighboring areas of Argentina (Fig. 28).

ARGENTINA (38): Chubut (9): Lago Puelo, Parque Nacional Los Alerces ; Neuquén (26): Parque Nacional Lanín, Pucará, San Martín de los Andes; Río Negro (3): El Bolsón, Lago Guillelmo .

CHILE (123): Biobío (5): La Invernada, Ñuble, Las Trancas ; La Araucanía (11): Cherquenco, Curacautín , Parque Nacional Huerquehue, Malleco, Villarrica ; Los Ríos (9): Monumento Nacional Alerce Costero, Llifen, Valdivia ; Los Lagos (36): Ahoni , “Chiloe”, Dalcahue, Lago Chapo, Llanquihue, Palena, Puerto Varas, Parque Nacional Puyehue ; Aisén (62): Aisén , Coihaique. No data (6) .

Temporal distribution. January (32), February (119), March (7), June (1), November (4), December (5).

Diagnosis. This species is the most readily identifiable in the genus (Figs 14–15). The large ventral tooth on the mandibles of males, smooth and apparently glabrous

elytra, and spinose elytral apex in both sexes are diagnostic. Male majors, with their extremely elongate mandibles and large size, cannot be confused with any other species.

Remarks. Stephens (1831) described C. grantii based on a single holotype specimen. This specimen was found in the University of Cambridge Museum of Zoology, U.K. The holotype was likely part of the Stephens collection that was acquired by the Cambridge Philosophical Society. The entire insect collection of the Cambridge Philosophical Society was turned over to the University of Cambridge in 1865 as the foundation of a museum collection at the university. Unfortunately, none of the Stephens specimens were properly labeled so we had to match the attributes of this particular specimen to the original illustrations of Stephens (1831) to verify that it is the holotype. The male mandibles of this species can display great variation in their length, thickness, and curvature, and this specimen perfectly matches the specific curving and unusually large and thick mandibles of the original illustration. Specimens of such great size are relatively rare, and the general way the specimen is mounted also closely matches the original illustrations. The fact that this specimen was the only C. grantii specimen found in the University of Cambridge Museum of Zoology (the subsequent depository of Stephens’ collection) and that it matches the original description and illustrations gives us enough evidence to state that this specimen is the holotype. Stephens (1831) reported that a Chilean collected this specimen in January on Chiloé Island and gave it to Dr. Grant, who was the surgeon on board the H.M.S. Forte.

The immense variation in size in this species has prompted the continued use of the name ‘ pygmaeus’ for the smaller males despite any evidence that would suggest distinct populations or genetic uniqueness. The idea remains tempting to amateur collectors, possibly because even these smaller males are of a similar size (and show the same amount of allometric development) as male majors of other species such as C. mniszechii . The development of male majors in C. grantii that are twice-again as large, and how this relates to the breeding behavior of the species, is something that deserves to be studied in more detail.

Benesh (1960), and thus Krajcik (2001), listed C. pygmaeus under synonymy with C. latreillei despite the photograph in the original that clearly depicts a small C. grantii . Nevertheless, this demonstrates the existence of some confusion about the taxon and that the designation of a neotype is warranted.

Natural History. Grant’s stag beetle, sometimes referred to as Darwin’s stag beetle, is the largest species in the genus and one that commands a great deal of attention. Other common names for the species include ciervo volante, llico-llico, and cantábria. The species was observed by Darwin in Chile ( Darwin 1871): “The male Chiasognathus grantii of South Chili – a splendid beetle … has enormously-developed mandibles; he is bold and pugnacious; when threatened on any side he faces round, opening his great jaws, and at the same time stridulating loudly; but the mandibles were not strong enough to pinch my finger so as to cause actual pain.” Darwin’s observations were expanded by Joseph (1928) and Hamilton (2000) with further discussion on the behavior of C. grantii males. To this we add our own observations made while collecting in Chile. Males of C. grantii are energetic and will attempt to pinch with their elongate mandibles when handled. As noted by Arrow (1951), the bite of a female would be much more painful, although the sharp mandibular apex of males can draw blood (ABTS, personal observation). Males will raise up on their middle and hind legs when threatened or when approached by another male (Fig. 1). When another male is introduced, the two individuals will move together and adopt this aggressive posture and will then battle each other. Each will attempt to grip with their mandibles around the lateral teeth of the pronotum of their opponent. Once a strong grip is established there is an attempt to lift the opponent and drop it to the ground. When a female is introduced, the successful combatant will adopt an apparent mate-guarding stance with his mandibles and legs arched over the female (Fig. 2) and will battle any other males that approach. Hamilton (2000) reported that male combat occurs either in trees, where the females feed on sap, or among the flowers of the native canelilla, a climbing hydrangea ( Hydrangea serratifolia (H. et A.) F. Phil ( Hydrangeaceae )). Adults have been reported to feed on the sap of Nothofagus betuloides (Mirbel) Oersted , N. nitida (Phil.) Krassen , N. obliqua (Mirbel) Oersted (Fagaceae) , and Weinmannia trichosperma Cav. (Cunoniaceae) ( Joseph 1928; Vergara and Jerez 2009). As with other chiasognathines, larvae live in the soil ( Joseph 1928). Adults may be seen flying just before dark and are attracted to light.

Arrow (1904) discussed the stridulatory mechanism present in adults of both sexes of C. grantii , and that it is composed of a ridged elytral margin and corresponding grooves on the hind femora. These modifications are not present in the other species in the genus, thus sound production in the adult appears to be an autapomorphy of this species that may be related to the larger size and threat display behavior.