Bothynus nyx Ratcliffe, 2010

Ratcliffe, Brett C., 2010, A New Bolivian Bothynus Hope, 1837 (Coleoptera: Scarabaeidae: Dynastinae: Pentodontini), with a Key to the Species in Bolivia, The Coleopterists Bulletin 64 (2), pp. 105-108 : 105-107

Bothynus nyx Ratcliffe , new species ( Figs. 1–4 )

Type Material. H o l o t y p e m a l e, l a b e l e d “ BOLIVIA: Dep. Santa Cruz / Bermejo, Refugio Los Volcanes/ Hotel area, 18°06′18″S 63°35′54″W / 09.xii.2003, at night/ coll D. J. Mann & A. C. Hamel // OUMNH-2004-005/ D.J.Mann & C. Hamel coll./ Pres. Mann & Hamel, 2004”/ my holotype label. Single male paratype labeled “Chiquitos, BOLIVIA / Dept. Sta. Cruz / XI.59”, my paratype label. Holotype deposited at the Hope Entomological Collections at Oxford University, United Kingdom. Paratype deposited in the B. C. Ratcliffe collection (Lincoln, Nebraska) .

Holotype. Male. Length 34.5 mm; width across humeri 18.0 mm. Color dark reddish brown. Head: Frons concentrically, coarsely rugopunctate. Frontoclypeal ridge strongly elevated, slightly arcuate, not quite reaching lateral margins. Clypeus transversally, coarsely rugose; apex gradually contracted to 2 small, broadly spaced, rounded, reflexed teeth. Interocular width equals 3.8 transverse eye diameters. Antenna with broad club, club slightly longer than segments 2–7. Mandibles tridentate with 2 small, apical teeth and basal, rounded tooth. Pronotum: Anterior two thirds of pronotum with large, transversely oval fovea; fovea anteriorly with strong tubercle, posteriorly with strong, binodose ridge at center base. Surface in fovea transversely rugose, remainder of surface on anterior half with slightly transverse punctures; punctures moderately dense, moderately large. Surface on posterior third crazed, with small, sparse punctures. Base transversely rugopunctate in narrow band on central third. Elytra: Surface weakly shining, minutely shagreened, with moderately impressed, punctate striae; punctures in striae small to moderate in size, ocellate. Sutural stria present. Intervals similar, but irregularly spaced, punctures becoming dense at apical angles. Sides behind humerus vaguely wrinkled and with similar, irregular punctures. Humeral and apical umbones noticeably prominent. Propygidium: Apex arcuate, only slightly projecting posteriorly so that pygidium is nearly “normal” in length. Pygidium: Surface completely, transversely rugulose. Basal fourth with short, moderately dense, reddish brown setae. In lateral view, surface evenly convex. Legs: Protibia tridentate. Protarsus with claws equal in size, median claw with ventral swelling. Metatibia with 2 transverse carinae on lateral surface, apex broadly rounded and with 20–25 “sockets” for stout setae (many setae abraded away). Apex of basal tarsomere of metatarsus elongated into stout, triangular spine. Venter: Prosternal process moderate in length, apex round, clothed with dense, long, reddish brown setae. Parameres: Shaft, in caudal view ( Fig. 3 ), stout and nearly straight to apex; strongly falcate in lateral view ( Fig. 4 ).

Variation. Males (1 paratype). Length 31.3 mm; width across humeri 15.5 mm. The paratype does not differ significantly from the holotype, except that the median claw of the protarsus has a distinct tooth on the ventral surface ( Fig. 2 ). In the holotype, this area is represented by a swelling only, perhaps due to wear.

Etymology. In the cosmogony of Hesiod in Greek mythology, Nyx was the goddess of the night, one of the first-born, elemental gods that came from air, chaos (Khaos) ( Atsma 2008) (see also quote at beginning of paper). This species is so named in reference to the nocturnal habits of adult Bothynus species.

Distribution. Bothynus nyx is known only from the department of Santa Cruz in south-central Bolivia on the eastern slope of the Andes. Los Volcanes is located about 50 km west of Santa Cruz, and San José de Chiquitos is about 250 km east of Santa Cruz.

Diagnosis. Bothynus nyx most closely resembles Bothynus laevipennis Arrow in overall appearance. Bothynus nyx is distinguished by the presence of a ventral tooth on the median claw of the protarsus ( Fig. 2 ), whereas the claw in B. laevipennis is simple. In addition, the shaft of the parameres of B. nyx , in caudal view ( Fig. 3 ), is stout and nearly straight to the apex, whereas the shaft in B. laevipennis ( Fig. 5 ) is distinctly constricted before the apical lobe. In lateral view, the parameres of B. nyx are strongly falcate ( Fig 4 ), whereas the parameres of B. laevipennis are bluntly subtriangular ( Fig. 6 ).

KEY TO THE SPECIES OF ADULT MALE BOTHYNUS OF BOLIVIA (modified from Endrödi 1985) (females are best identified by association with males)

1. Elytra smooth, without impressed striae ......2

1′. Elytra with distinctly impressed, punctate striae ..............................................................3

2. Protarsus of male with median claw incised. Metatibia lacking basal, transverse carina; apex with about 40 mostly slender setae. Parameres of male with large, acute, ventral tooth. Length 24–30 mm ............................... ...................................... B. medon (Germar)

2′. Protarsus of male with median claw entire, not incised. Metatibia with basal, transverse carina present (although usually very weak); apex with 25–35 short, stout setae. Parameres of male with large, angulate lobe on venter. Length 22–30 mm .......................................... ............................. B. cunctator Mannerheim

3. Protarsus of male with median claw simple .........................................................................4

3′. Protarsus of male with median claw toothed beneath ( Fig. 2 ). Length 32–35 mm ............. .............................................. B. nyx Ratcliffe

4. Elytra weakly striate. Pygidium completely rugulose. Length 26–37 mm .......................... ..................................... B. laevipennis Arrow

4′. Elytra strongly striate. Pygidium with disc smooth or with sparse punctures. Length 13–25 mm ............ B. striatellus (Fairmaire)

Figures

Fig. 1. Bothynus nyx. Scale bar = 5 mm.

Figs. 2–6. 2) Median claw of left protarsus of Bothynus nyx paratype showing tooth; 3–4) Parameres, caudal (arrow indicates straight shaft) and lateral views, of Bothynus nyx; 5–6) Parameres, caudal (arrow indicates constricted shaft) and lateral views, of Bothynus laevipennis.