Mecyclothorax taatitore, Liebherr, James K., 2013

Liebherr, James K., 2013, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands, ZooKeys 322, pp. 1-170 : 88-89

69. Mecyclothorax taatitore sp. n.

Diagnosis.

This species and Mecyclothorax georgettae are isolated within the Mecyclothorax globosus group by their moderately broad pronotal lateral margins, but the bisetose, cordate pronotum and small body size are consistent with group membership. Both species exhibit a unique synapomorphy within the Tahitian Mecyclothorax fauna; the elongate basal fusion of sutural stria 1 and stria 2 (Figs 37B, C). Beside the well-developed elytral microsculpture used in the key, this species may be diagnosed from Mecyclothorax georgettae by the obovate elytra, the elytral base narrow and humeri proximate, MEW/HuW = 2.23-2.57 (n = 5). Setal formula 2121; standardized body length 4.1-5.0 mm. Head with triangularly depressed frontal grooves, the apex a fine low carina just mesad the anterior supraorbital seta, the grooves expanded medially across frons to nearly meet at frontoclypeal suture, the frons transversely wrinkled behind, obliquely wrinkled anteriorly; eyes moderately convex, dorsal margins convergent at supraorbital setae, ocular ratio 1.53-1.57, ocular lobe gently protruded from gena, ocular lobe ratio 0.78-0.82; antennae moderately elongate, submoniliform, antennomere 8 length 1.80 × maximal breadth. Pronotum little transverse, MPW/PL = 1.14-1.25 (n = 5), narrow basally, lateral margins convergent anterad right to slightly obtuse hind angles, MPW/BPW = 1.44-1.54; median base distinctly depressed relative to convex disc, with ~24 punctures each side, the punctures anastomosing laterally, and punctures along margin with disc elongate; anterior transverse impression very shallow medially, obscured by 10-12 fine longitudinal wrinkles that extend across slightly convex anterior callosity; front angles protruded, tightly rounded, lateral marginal depression narrowest just before lateral pronotal seta, the edge upturned, broader inside front angles and posteriorly; laterobasal depression a broadened extension of lateral depression, the surface rugose due to transverse wrinkles that span the laterobasal depression and basal portion of lateral depression. Elytra broadly convex medially, the sides laterad interval 6 more sloped to near vertical juncture with lateral marginal depression; elytral basal groove distinctly curved to the angulate humerus, striae 1 + 2, 3-5 deep and continuous to basal groove mesad humerus; discal striae 1-7 deep, indistinctly punctate before midlength; sutural interval 1 and scutellum elevated relative to intervals 3 and 4 basally; all striae complete to apex though broader and shallower than on disc, striae 1 and 7 the narrowest of them apically, interval 8 the same convexity as inner intervals except apically where intervals narrows to its terminus; lateral elytral setae 7 + 6. Microsculpture of frons and vertex a well-developed transverse mesh visible amongst the transverse wrinkles, sculpticell breadth 2 –4× length, more elongate in wrinkles, neck with isodiametric sculpticells near pronotum; pronotal disc with indistinct elongate transverse mesh, microsculpture also covering median base among punctures, the sculpticells there a mix of isodiametric and transverse. Coloration of head rufobrunneous with piceous cast in frontal grooves; antennomere 1 flavous, 2-3 rufoflavous, and 4-11 brunneous; pronotal disc rufobrunneous to rufopiceous, lateral pronotal margins narrowly rufoflavous; elytra darkest on discal intervals 2-4, progressively paler laterally and apically, the coloration varying from a piceous cloud on disc and flavous lateral marginal depression (as in Fig. 37C), to more uniformly brunneous with the disc only slightly darker (Fig. 37B), sutural interval paler than piceous cloud when latter present; femora and elytral epipleuron flavous, tibiae rufoflavous with rufous cast.

Male genitalia. In keeping with the isolated external anatomy of this species within Tahitian Mecyclothorax spp., the aedeagal median lobe is very broad basally and terminated apically by a short, distinctly pointed apex with variably curved ventral margin (Figs 3F, 40A); ostial canal not apparent, extended only a short distance beyond ostium along dorsal margin of lobe (Figs 3F, 40B); internal sac broad, with diffuse ventral ostial microtrichial patch and denser more spiculate dorsal ostial microtrichial patch; flagellar plate moderately elongate, length 0.42 –0.46× distance from parameral articulations to tip (Figs 3F, 40B).

Female reproductive tract. Bursa copulatrix broad, slightly expanded apically, length 1.6 × maximal breadth compressed under microslide cover slip (Fig. 33D); basal gonocoxite 1 with apical fringe of 3-4 setae laterally, these setae basad lateral ensiform setae of apical gonocoxite 2, and one seta isolated medially near basal condyle of gonocoxite 2 (Fig. 9E); medial surface of gonocoxite 1 lined with setae, a somewhat larger seta at the medioapical angle, and 8-11 smaller setae arrayed basally; apical gonocoxite 2 stout, moderately expanded basolaterally, apex rounded, with two short lateral ensiform setae, one dorsal ensiform seta, and an apical sensory furrow with two apical nematiform setae and two furrow pegs.

Holotype male (MNHN) labeled: French Polynesia: Tahiti Nui / Mt. Marau road el. 1165 m / 4-IX-2006 lot 03 / 17°36.440'S, 149°32.877'W / pyrethrin fog rheocrene w/ / moss/liverwort J.K. Liebherr // HOLOTYPE / Mecyclothorax / taatitore / J.K. Liebherr 2013 (black-bordered red label).

Allotype female (MNHN) labeled as the holotype.

Paratypes: labeled as the holotype (CUIC, 6; EMEC, 1; NMNH, 1).

Etymology.

The species epithet compounds the Tahitian words tā’ati, meaning unite or join together, and tore, which means, among other things, streaked, or military stripes. The epithet signifies the fused bases of elytral striae 1 + 2.

Distribution and habitat.

These beetles were discovered by pyrethrin fogging a wet rock face above a small stream. The rock face lay on the sidewall of a small gulch that was shaded by trees, and was about 6 m in height and about 10 m across, the fractured face lying at a 75° angle to the horizontal. The surface was covered with mosses and liverworts, and the beetles crawled out of the cracks due to the action of the pyrethrin. One adult and four larvae of Colpodes eremita (Fairmaire) were also found escaping cracks in the rock after the pyrethrin application.