Mecyclothorax octavius 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 : 28-30

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/003616EF-AF92-4481-864C-A91512EC417E
taxon LSID	lsid:zoobank.org:act:003616EF-AF92-4481-864C-A91512EC417E
treatment provided by	Deutsche Entomologische Zeitschrift by Pensoft
scientific name	Mecyclothorax octavius Liebherr
status	sp. n.

Treatment

8. Mecyclothorax octavius Liebherr sp. n. Figures 16C View Figure 16 , 17E-F View Figure 17 , 18C View Figure 18 , 19 View Figure 19

Diagnosis.

This species (Fig. 16C View Figure 16 ) exhibits superficial similarity to M. fleutiauxi and M. jeanneli (Fig. 9D-E View Figure 9 ), but differs in: 1, larger body size, standardized body length 5.8 mm; 2, presence of both anterior and posterior supraorbital setae; 3, an unmargined and depressed pronotal median base with sinuate lateral margins anterad the obtusely rounded hind angles; and 4, eyes of very small diameter, i.e. ocular lobe ratio = 0.71 versus ratios of 0.89-0.94 for individuals of the former two species. The male aedeagus is completely different, exhibiting a flagellum and flagellar sheath, and a dorsoventrally expanded apex (Fig. 17E View Figure 17 ). Chaetotaxy +/+//+/-//+/2/+/+.

Description

(n = 1). Head capsule elongate, distinctly broader at the small, moderately convex eyes, ocular lobe gradually curving to meet gena well behind eye posterior margin; 20 ommatidia along horizontal diameter of eye; ocular ratio 1.45, ocular lobe ratio 0.71, EyL/EyD = 2.4; frontal grooves deep, sinuously convergent to just posterad clypeus, 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 twice as far beyond ligular margin as their basal length to margin, apex observably spiculate (100 ×); antennae elongate, antennomere 9 length 2.3 × maximal breadth; antennomere 3 with glabrous except for apical ring of setae. Pronotum transverse, vase-shaped, median base depressed relative to broadly convex disc, lateral margins evenly curved until joined to long median peduncular collar, pronotal lateral margin obtusely concave at the juncture (Fig. 16C View Figure 16 ); MPW/BPW = 2.4, MPW/PL = 1.1; front angles narrowly protruded, obtuse, pronotal apex constricted, APW/BPW = 1.35; median base trapezoidally depressed relative to convex disc, 8-10 small punctures present each side, lateral marginal bead continued along anterior half of basal peduncle, terminated at base of peduncle, median base unmargined posteriorly; median longitudinal impression very finely incised on disc, extended briefly anterad broad and shallow anterior transverse impression; anterior transverse impression very broad, very shallow, indistinctly traceable to front angles; proepisternum separated from prosternum by a deep, sinuous groove both anteriorly and ventrally; prosternum with anteapical impression that is continuous ventrally; prosternal process narrowly and deeply depressed between procoxae, depression extended anteriorly half the distance to prothoracic anterior margin, the depression broadest at anterior terminus. Elytra ellipsoid, broadest just anterad midlength; MEW/EL = 0.72; basal groove absent from very narrowly pedunculate elytral base, the very narrow lateral marginal depressions converging on posterior margin of pronotum; striae 1-7 very shallow though traceable , stria 8 deep, diverging from stria 9 just posterad anterior series of lateral elytral setae; all striae except 8 absent from elytral apex; apical elytral setae positioned only slightly nearer to suture than subapical seta; elytra appressed and conjoined at apex, the upraised sutural margin forming an elongate isosceles triangle connected to the narrowly beaded elytral apical margin. Pterothoracic mesepisternal anterior surface with eight broad punctures, the largest anterior puncture separated from the remainder by a vertical ridge; mesosternal-mesepisternal suture incomplete, obsolete to absent anteriorly (as in Fig. 3B View Figure 3 ); metepisternum very short, maximum width/lateral length = 1.46 (difficult to measure due to fusion of metepisternum and metepimeron). Abdomen with first and second ventrites fused laterally, not suture visible; 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, an indistinct transverse mesh on a glossy surface, microsculpture on vertex an evident transverse mesh with some isodiametric sculpticells; pronotal disc and base with fine, elongate transverse mesh, sculpticell breadth 3-4 × length, surface iridescent; elytra with evident transverse mesh, sculpticell breadth 2-3 ×length; elytral apex with elongate transverse mesh, sculpticell breadth 3-4 × length where traceable.

Male genitalia (n = 1). Antecostal margin of abdominal mediotergite IX angulate, not extended (Fig. 17F View Figure 17 ); right paramere elongate, slightly expanded dorsally in basal half, narrowly extended apically (Fig. 18C View Figure 18 ), with 13 setae along the apical 2/3 of the ventral margin, those setae complementing two elongate apical setae; left paramere moderately broad basally, evenly narrowed to a moderately extended, narrow apex, two small setae present apically; aedeagal median lobe gracile, tubular, straight at midlength, with apex broadly expanded dorsoventrally, dorsally to am obtuse point, ventrally in a tightly rounded and projected margin; aedeagal median lobe internal sac with flagellum and flagellar sheath, apparently unilobate based on interpretation of uneverted unique type male (Fig. 17E View Figure 17 ), a diffuse spicular patch apicad flagellar apparatus, no structure present at position of dorsal plate.

Type -Holotype male (MNHN): NEW CALEDONIA / Me Maoya, summit / plateau.12Nov2002. / Monteith & Burwell // QM Berlesate 1080 / 21°22 ’Sx165°20’ / rainforest, 1400 m/ / sieved litter // QUEENSLAND / MUSEUM LOAN / DATE: Nov. 2003 / No. LEN-1686 (green label) // New Caledonia Mecyclothorax revision / measured specimen 1 / J.K. Liebherr 2016 ♂1 // genitalia in polyethylene vial with glycerine // HOLOTYPE / Mecyclothorax / Mecyclothorax megalovatulus / J.K.Liebherr 2017 (black-bordered red label) .

Etymology.

Given that the body form comprises a pair of ovoids (Fig. 16C View Figure 16 ) suggesting the numeral eight, this species is given the epithet Mecyclothorax octavius . As a Latin personal name, denoting the eighth-born son, or a son born in the eighth month, the species name is to be treated as a noun.

Distribution and habitat.

The single specimen of this species was collected from sieved litter collected at the 1400 m summit of Mt. Maoya (Fig. 19 View Figure 19 ). This species is adelphotaxon to the species triplet M. plurisetosus ( M. fleutiauxi + M. jeanneli ), all of whom are most commonly found in arboreal microhabitats, supporting transformation of habitat preference to the arboreal realm in their common ancestor.