Mecyclothorax kanak Moore & 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 : 37-43

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/062E8A3B-6762-429F-B2D7-669FB5A2AE14
taxon LSID	lsid:zoobank.org:act:062E8A3B-6762-429F-B2D7-669FB5A2AE14
treatment provided by	Deutsche Entomologische Zeitschrift by Pensoft
scientific name	Mecyclothorax kanak Moore & Liebherr
status	sp. n.

Treatment

14. Mecyclothorax kanak Moore & Liebherr sp. n. Figures 1H View Figure 1 , 20D-G View Figure 20 , 21A-K View Figure 21 , 22A View Figure 22 , 23D-E View Figure 23 , 24D View Figure 24 , 26 View Figure 26

Diagnosis.

This second of the species triplet also including M. mouensis and M. picdupinsensis can be diagnosed externally by characters listed in the M. mouensis diagnosis. This species and the following M. picdupinsensis are adelphotaxa based on possession of the synapomorphous hitch on the apical surface of the male aedeagal median lobe (Fig. 7 View Figure 7 , character 112, state 1). This species can be diagnosed from M. picdupinsensis by the hitch configuration being a well-developed apical invagination (Fig. 21A-D, F-K View Figure 21 ), the level of invagination, curvature and length of the apex varying among populations assigned to this species (Fig. 26 View Figure 26 ). In these instances the apical invagination is much more developed than in the sister species below (Fig. 21L-N View Figure 21 ). Much like the externally-cryptic species pair M. fleutiauxi and M. jeanneli (Fig. 9D-E View Figure 9 ), these two species are indistinguishable based on external characters. They are treated as distinct species because just as in the M. fleutiauxi + M. jeanneli pair, female reproductive tract characters also differ between the two taxa. In M. kanak females, the bursa copulatrix is more parallel-sided in ventral view, with the apex narrowed (Fig. 23D-E View Figure 23 ). Also, the basal gonocoxites bear a narrow, spiculate mediobasal band of fine, setose spicules (Fig. 24D View Figure 24 ), versus basal gonocoxites with a broader spiculate mediobasal band of spatulate spicules in M. picdupinsensis (Fig. 24E View Figure 24 ). Standardized body length 3.0-3.8 mm (Fig. 20D-F View Figure 20 ) for all population samples except that from Col de Yaté, for which the three specimens range 2.9-3.2 mm length (Fig. 20G View Figure 20 ). Chaetotaxy +/+//+/-//+/2/+/+.

Description

(n = 24). Head capsule elongate, eyes small, very convex, ocular lobe-genal juncture evenly curved, a very shallow groove indicating limit of ocular lobe; 12-14 ommatidia along horizontal diameter of eye; ocular ratio 1.41-1.54, ocular lobe ratio 0.74-0.81, EyL/EyD = 2.16-2.45; frontal grooves narrowly incised, sinuously convergent to pit at frontoclypeal suture, extended onto clypeus; mandibles moderately elongate, mandibular ratio 1.60; ligula narrowed to a moderately broad, slightly convex anterior margin, the two ligular setae separated by 1-2 setal diameters; paraglossae thin, extended twice as far beyond ligular margin as their basal length to margin, apex visibly spiculate (100 ×); antennae moderately elongate, antennomere 9 length 2.1 × maximal breadth; antennomere 3 glabrous except for apical ring of setae. Pronotum very transverse, distinctly cordate, lateral margins sinuately concave anterad obtuse-rounded hind angles (Fig. 20D-G View Figure 20 ), MPW/BPW = 2.31-2.64, MPW/PL = 1.27-1.37; front angles slightly protruded, obtuse, APW/BPW = 1.27-1.48; median base unmargined basally, trapezoidally depressed relative to disc, the median longitudinal impression divided basally into two transverse impressions that isolate disc from base, each transverse basal impression terminated laterally in a short linear laterobasal depression; median longitudinal impression finely incised on disc, terminated anteriorly just anterad anterior transverse impression, a narrow fovea at posterior juncture with basal transverse impressions; anterior transverse impression shallow, broad, traceable to front angles; proepisternum separated from prosternum by a shallow groove anteriorly, and deep, distinct groove ventrally; smooth anteapical impression well developed laterally, continuous though shallower ventrally; prosternal pro cess broadly, shallowly depressed between procoxae, the shallow depression extended 1/3 distance toward anterior prothoracic margin. Elytra broadly hemiovoid, humeri well-extended laterally before lateral margins curve posteriorly; basal elytral groove posteriorly curved laterad obtuse humeral angle, with three punctate depressions at the base of sutural and striae 5 and 5; MEW/EL = 0.81-0.93; sutural stria well developed in basal 2/3, striae 2-3 traceable on disc near positions of dorsal elytral setae, all three irregularly depressed with intermittent crenulations or elongate punctures along their length; stria 4 indicated by an intermittent series of shallow longitudinal depressions; striae 1 and 2 shallow and traceable, and stria 8 evident on elytral apex; elytra appressed and conjoined apically, the sutural margin upraised at apex. Pterothoracic mesepisternal anterior furrow with 5 depressions in 1-2 irregular rows; mesosternal-mesepisternal suture complete (as in Fig. 3A View Figure 3 ); metepisternum foreshortened, lateral length/maximum width = 1.1-1.25; metepisternal-metepimeral suture complete though fine laterally. Abdomen with very elongate, shallowly curved crescent-like depression along suture between first and second ventrite, second ventrite only slightly depressed within crescent; suture between second and third ventrites reduced though traceable laterally; ventrites 3-6 with broad, shallow, linear plaques near lateral margin. Microsculpture of frons reduced, surface glossy, indistinct transverse mesh-sculpticell breadth 2 × length-visible over portions of vertex; pronotal disc glossy but with transverse sculpticells visible outside areas of reflection, trapezoidal median base glossy with indistinct transverse mesh anterad laterobasal depression; elytra opalescent, disc covered with very finely separated transverse lines, elytral apex covered with elongate transverse sculpticells and lines.

Male genitalia (n = 25). Antecostal margin of abdominal mediotergite IX angulate, not extended (Fig. 21B, D, G, I View Figure 21 ); right paramere narrow, extended as a very narrow whiplike extension which flexibly articulates with the base, both ventral and dorsal margins glabrous, with two apical setae (Fig. 22A View Figure 22 ); left paramere moderately broad basally, evenly narrowed to a whiplike apex, two longer apical setae present; aedeagal median lobe variously robust, broader relative to length in specimens with a shorter aedeagal apex (Fig. 21A, F View Figure 21 ), and narrower relative to length in males with more gracile median lobes (Fig. 21C, H, J View Figure 21 ); median lobe apex variously bifurcate-except for the infraspecific variant, form Q discussed below (Fig. 21E View Figure 21 )-with an apical aedeagal invagination laterally splitting the tip, that invagination continued laterally on the median lobe toward the ostial opening (Fig. 21A, C, F, H, J View Figure 21 ); aedeagal apex variously extended and curved, from short and broad, and briefly extended beyond the ostial opening (Fig. 21A, F View Figure 21 ), to more elongate broadly extended and slightly downturned (Fig. 21H View Figure 21 ), to more elongate and narrowly extended (Fig. 21C View Figure 21 ), to very narrowly extended and distinctly curved (Fig. 21J View Figure 21 ); median lobe internal sac with translucent dorsal plate, most visible in well-sclerotized specimens (Fig. 21A, E, J View Figure 21 ), and a longitudinal apical field of microspicules (Fig. 21A, J View Figure 21 ).

One of a series of nine males from Mt. Humboldt, 1300 m el., 6-7-xi-2002, Monteith & Wright, lot 1076 (QMB) exhibits a broad aedeagus with a rounded tip, the ostial opening more asymmetrical apically (Fig. 21E View Figure 21 ), herein dubbed form Q. The other eight males of this particular collecting series all exhibit aedeagal apices similar to those from Mt. Humboldt, 1400 m (Fig. 21C View Figure 21 ). There are no external differences discernible among the males of this series, and no other examined male from Mt. Humboldt or anywhere else across the distributional range exhibits the "form Q" aedeagal configuration. Therefore this form is considered an infraspecific variant without nomenclatural status, with its evolutionary basis requiring further study.

The geographic pattern of aedeagal configuration shows that populations in the southern end of the range include males with a longer, narrower, and more curved aedeagal apex (Fig. 26 View Figure 26 , populations G, H, I). The extreme of this trend is observed in two males from Col de Yaté (Fig. 26 View Figure 26 , population G). The beetles comprising the Col de Yaté sample also tend to be smaller, though the size range of the three specimens of this population sample overlap the ranges of other populations, precluding diagnosis by size. Given the trend toward longer, narrower aedeagal apices in the south, and the demonstrated variation in aedeagal apices among other population samples (e.g. Fig. 26 View Figure 26 , population samples C, F), this variation is considered infraspecific.

Female reproductive tract (n = 4). Bursa copulatrix length 1.1-1.4 × circumference, its surface thin, translucent, slightly to not wrinkled (Fig. 23D-E View Figure 23 ); spermathecal duct entering at apex of bursa separate from bursa-common oviduct juncture; rounded helminthoid sclerite on bursal wall between, and separate from both, bursal-common oviduct juncture and spermatheca; spermatheca of only slightly greater circumference than spermathecal duct, reservoir about 1/2 length of spermathecal duct, spermathecal gland duct entering at base of spermathecal reservoir (Fig. 23E View Figure 23 ); ligular apophysis present on common oviduct; basal gonocoxite 1 with apical fringe of two to unilaterally three setae laterally, a very small setae may be present immediately mesad, and several smaller setae occur along apex of medial margin (Fig. 24D View Figure 24 ); medial margin bearing a dense field of spiculate microtrichia basally, this field about 3-4 microtrichia broad and appearing like the hooklike surface of a Velcro® closure; gonocoxite 2 moderately broad basally, basal width 1/2 medial length; two gracile lateral ensiform setae of moderate length present.

Types - Holotype male (MNHN): NEW CALEDONIA / Mt Dzumac / 28 May 1987 / R.Raven // Q.M. Berlesate No. 800 / 22°03'S. 166°28'E. / Rainforest 900m / Litter // QUEENSLAND / MUSEUM LOAN / DATE: Nov. 2003 / No. LEN-1686 (green label) // HOLOTYPE / Mecyclothorax / kanak / B.P. Moore & J.K. / Liebherr 2017 (black-bordered red label).

Paratypes (181 specimens; CUIC, EMEC, MBC, MHNG, MNHW, NHMW, PMGC, QMB): see Suppl. material 2.

Etymology.

This species is named to honor the Kanak people of New Caledonia. As the species epithet kanak is not derived from Latin, it is to be treated as indeclinable (I.C.Z.N. 1999, Article 31.2.3). Dr. B. P. Moore diagnosed this species from the preceding sibling species M. mouensis , and as such it is appropriate that he receive senior authorship for the species.

Distribution and habitat.

This species is densely and abundantly distributed across the southern reaches of Grande Terre, with records from Mt. Humboldt south to Forêt Nord (Fig. 26 View Figure 26 ). Collecting localities range from 70 m elevation along the Tontouta River, to 1500 m on the slopes of Mt. Humboldt. Professor Alexander von Humboldt ( Wulf 2015) would no doubt be very interested to learn that this species occurs from 580-1500 m elevation on his namesake mountain, inhabiting lowland rain forest, montane rain forest, and high-altitude maquis ( Mueller-Dombois and Fosberg 1998), where this species was collected from sifted litter under Callitris neocaledonica Dümmer (1, Wanat, MNHW). Of the 177 specimens examined, 133 were labeled as collected in sieved litter or by Berlese extraction. A further 34 specimens ( Löbl, MHNG) can also be assigned as the products of these methods. This leaves the remaining 6% of specimens to be divided between such collecting methods as headlamp search at night, "at light", flight intercept trap, and no data. Thus this species can be characterized as a fastidious denizen of the ground-level litter layer.