Mecyclothorax plurisetosus Liebherr, 2018

Liebherr, James K., 2018, Cladistic classification of Mecyclothorax Sharp (Coleoptera, Carabidae, Moriomorphini) and taxonomic revision of the New Caledonian subgenus Phacothorax Jeannel, Deutsche Entomologische Zeitschrift 65 (1), pp. 1-63 : 24-26

publication ID	https://dx.doi.org/10.3897/dez.65.21000
publication LSID	lsid:zoobank.org:pub:73DEE0F3-2BB0-4A21-B445-5E168FE50F54
persistent identifier	https://treatment.plazi.org/id/CE1562F9-33FE-440C-AE08-E6B1DFF160B0
taxon LSID	lsid:zoobank.org:act:CE1562F9-33FE-440C-AE08-E6B1DFF160B0
treatment provided by	Deutsche Entomologische Zeitschrift by Pensoft
scientific name	Mecyclothorax plurisetosus Liebherr
status	sp. n.

Treatment

6. Mecyclothorax plurisetosus Liebherr sp. n. Figures 12F View Figure 12 , 13F View Figure 13 , 16A View Figure 16 , 17A-B View Figure 17 , 18A View Figure 18 , 19 View Figure 19

Diagnosis.

These beetles (Fig. 16A View Figure 16 ) share an orbicular pronotum and smooth ovoid elytra with the previous two species, M. fleutiauxi and M. jeanneli (Fig. 9D-E View Figure 9 ). This similarity in body form is indicative of phylogenetic relationship, as M. plurisetosus comprises the adelphotaxon to those species two (Fig. 7 View Figure 7 ). However this species can be diagnosed from all others by the presence of extra setae on the pronotum. In addition to the large setae homologized with the lateral pronotal setae, there are 9-11 smaller setae in the marginal depression anterad the lateral seta, and 4-5 setae in the depression behind the lateral seta. The prosternum also bears a sparse pelage of elongate setae, with the anterior surfaces of the femora also so covered. The elytral striae are totally reduced in this species, and the cuticular microsculpture also totally absent from head capsule, pronotum, elytra, and ventrites. Standardized body length 4.7-5.1 mm. Chaetotaxy +/+//2+11/-5//+/2/+/+, signifying that the lateral pronotal seta has been doubled, with up to 11 microsetae lining the lateral marginal depression anterad those setae. Also, though the basal pronotal seta is absent, up to 5 microsetae lie along the lateral margin near the pronotal base. The two lateral pronotal setae are longer and stouter than the anterior 11 and posterior 5 microsetae, supporting homology of the double setae with the single lateral pronotal seta of the other species, and the autapomorphic status of the numerous and variable microsetae.

Description

(n = 3). Head capsule trapezoidal, neck broad, with small, moderately convex eyes, ocular lobe meeting gena at obtuse angle very close to eye posterior margin; 18-19 ommatidia along horizontal diameter of eye; ocular ratio 1.28-1.42, ocular lobe ratio 0.88-0.91, EyL/EyD = 2.9-3.1; frontal grooves very deep, arcuately convergent at midlength, extended deeply onto clypeus; mandibles moderately elongate, mandibular ratio 1.8; ligular lateroanterior margin rounded to ligular seta, the two setae separated by one to two setal diameters; paraglossae thin, extended as far beyond ligular margin as half of basal length to margin; antennae very elongate, antennomere 9 length 3.4 × maximal breadth; antennomere 3 with sparse fine setae near apex in addition to apical ring of longer setae. Pronotum transversely ovoid, median base depressed relative to disc, lateral margins evenly curved to meet narrow median peduncular collar, pronotal lateral margin obtusely concave at the juncture (Fig. 16A View Figure 16 ); MPW/BPW = 3.6-3.9, MPW/PL = 1.23-1.25; front angles protruded, obtusely rounded, the apex broad to match broad base of head, APW/BPW = 2.1-2.3; basal margin bordered by broadly convex marginal bead that joins lateral marginal bead at sinuate margin, three deep pits anterad median marginal bead; median longitudinal impression very finely incised on disc, terminated ante riorly at position of anterior transverse impression; anterior transverse impression very broad, very shallow, indistinctly traceable to front angles; proepisternum separated from prosternum by a narrow, shallow groove both anteriorly and ventrally; prosternum without anteapical impression, though anterior margin is irregularly punctate; prosternal process narrowly depressed between procoxae, that depression not extended anteriorly, but venter of prosternum is flattened toward front of prothorax (as in M. fleutiauxi and M. jeanneli ). Elytra ovate, broadest in basal half and narrowed apically; MEW/EL = 0.81-0.85; basal groove very briefly extended laterad scutellum, the only indication of humeral angle being the basal groove’s juncture with the broader lateral marginal depression; striae 1-7 absent, only striae 8 and 9 (i.e. the inner portion of the elytral lateral marginal depression) present; only an obsolete vestige of the sutural stria evident at apex; elytra appressed and conjoined at apex where the sutural margin is narrowly and distinctly upraised. Pterothoracic mesepisternal anterior surface smooth except for a broad deep pit ventrally near prosternum; mesosternal-mesepisternal suture incomplete, obsolete to absent anteriorly (as in Fig. 3B View Figure 3 ); metepisternum foreshortened, maximum width/lateral length = 1.0; metepisternal-metepimeral suture incomplete, obsolete laterally. Abdomen with only a shallow crescent-shaped depression along suture between first and second ventrite, second ventrite little depressed posterad crescent; suture between second and third ventrites reduced though traceable laterally; ventrites 2-6 with broad, shallow, linear plaques near lateral margin. Microsculpture of frons reduced, surface glossy; pronotal disc and base with shallow transverse mesh, sculpticell breadth 3-4 × length; elytra glossy, only patchy indications of transverse microsculpture visible.

Male genitalia (n = 1). Antecostal margin of abdominal mediotergite IX angulate, an elongate "butterfly-net handle" extension distally (Fig. 17B View Figure 17 ); right paramere elongate, slightly convex dorsally near base, narrowly extended to apex (Fig. 18A View Figure 18 ), dorsal and ventral surfaces glabrous, two apical setae present; left paramere narrow basally, evenly constricted to a narrow, porrect apex, also glabrous except for two apical setae; aedeagal median love gracile, parallel-sided at midlength, the apex expanded dorsally to an acuminate point, and ventrally as a rounded projection (Fig. 17A View Figure 17 ); median lobe internal sac with evident crescent-shaped structure (Fig. 17A View Figure 17 ) homologous with flagellar sheath of above two species; folds of internal sac visible in the single uneverted type specimen interpreted as a bilobed sac as per the previous two species.

Female reproductive tract (n = 1). Bursa copulatrix unilobate, elongate, length about 3 × circumference, walls thin, slightly wrinkled (Fig. 12F View Figure 12 ); the only evidence of spermathecal configuration is a lightly sclerotized helminthoid sclerite near apex of bursa, spermatheca lost in single dissected female; basal gonocoxite 1 with apical fringe of 2 setae, lateral seta smaller, a few medial setae scattered along median margin (Fig. 13F View Figure 13 ); apical gonocoxite 2 moderately broad basally, breadth less than half of length; two lateral ensiform setae, apical seta much longer and broader than basal seta.

Types - Holotype male (MNHN): NEW CALEDONIA 8716 / 21°11 ’Sx165°18’.850m / Aoupinie, top camp, / 2-3Nov2001.C.Burwell& / GMonteith.pyr.trees,logs // QUEENSLAND / MUSEUM LOAN / DATE: Nov. 2003 / No. LEN-1686 (green label) // New Caledonia Mecyclothorax revision / measured specimen 3 / J.K. Liebherr 2016 // HOLOTYPE / Mecyclothorax / Mecyclothorax plurisetosus / J.K.Liebherr 2017 (black-bordered red label).

Paratypes (2 specimens): same locality and labeling as holotype (QMB, 1); Aoupinié summit, 1000 m el. [984 m; Google Earth Pro 2017], 21°11'S 165°16'E, pyrethrum trees & logs, 02-x-2004, lot 11665, Monteith (QMB, 1).

Etymology.

The presence of accessory setae on the pronotal lateral margins (Fig. 16A View Figure 16 ), prosternum, legs, and ventral body surface supports application of the compound adjectival epithet Mecyclothorax plurisetosus .

Distribution and habitat.

This species is known only from the upper elevations of Mt. Aoupinié (Fig. 19 View Figure 19 ), either from the vicinity of the summit transmitting station, or along the approach road at 850 m elevation. The four specimens were all collected via the application of pyrethrin spray to standing trees or downed logs. As this species is the adelphotaxon to M. fleutiauxi + M. jeanneli , finding it in this arboreal microhabitat supports the phylogenetic retention of preferred microhabitat among this triplet of species.