Mecyclothorax mouensis 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

13. Mecyclothorax mouensis Moore & Liebherr sp. n. Figures 2B , 17M-N , 18G , 20C , 23C , 24C , 25

Diagnosis.

This species, along with M. kanak and M. picdupinsensis , comprises a triplet of cryptic sibling species best determined using the male aedeagal median lobe. To that end, this species is characterized by a median lobe with the apex dorsally and ventrally subparallel beyond the ostial opening, and with the lobe’s apical face narrowly flattened (Fig. 17M ). All three species share broadly hemiovoid elytra, with this species exhibiting a broadly rounded basal groove across the humerus. Individuals of this species can be best diagnosed externally from those of the following two species by the broader elytral lateral marginal depression outside the anterior series of lateral elytral setae (Fig. 20C ). The anterior lateral elytral setae are situated in the lateral depression in beetles of this species, whereas they lie on the upraised lateral reaches of the elytral disc in M. kanak and M. picdupinsensis . Also the sutural stria is deep and smooth on the disc and striae 2-3 are evident and traceable to nearly obsolete in M. mouensis . This differs from the sutural stria in beetles of the following two species where the sutural stria is crenulate to indistinctly punctate on the disc. Standardized body length 2.8-3.4 mm. Chaetotaxy +/+//+/-//+/2/+/+.

Description

(n = 5). Head capsule elongate, eyes small, very convex, ocular lobe-genal juncture evenly curved, a very shallow groove indicating limit of ocular lobe; 11 ommatidia along horizontal diameter of eye; ocular ratio 1.43-1.48, ocular lobe ratio 0.73-0.77, EyL/EyD = 2.17-2.38; frontal grooves narrowly incised, sinuously convergent to pit at frontoclypeal suture, briefly extended onto clypeus; mandibles moderately elongate, mandibular ratio 1.73; ligula narrowed to a moderately broad, slightly convex anterior margin, the two ligular setae separated by one setal diameter; 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 2.0 × 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 (Figs 2B , 20C ), MPW/BPW = 2.43-2.82, MPW/PL = 1.35-1.39; front angles slightly protruded, obtuse, APW/BPW = 1.42-1.50; 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 laterally arcuate laterobasal depression; median longitudinal impression finely incised on disc, terminated anteriorly at 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 process broadly, shallowly depressed between procoxae, the shallow depression extended 1/2 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; MEW/EL = 0.85-0.91; sutural stria well developed in basal 2/3, striae 2-3 traceable on disc near positions of dorsal elytral setae, stria 4 indicated by an series of intermittent longitudinal depressions; only stria 8 evident on elytral apex; elytra appressed and conjoined apically, the sutural margin upraised at apex. Pterothoracic mesepisternal anterior furrow with five to six depressions in one to two irregular rows; mesosternal-mesepisternal suture complete (as in Fig. 3a ); metepisternum length and breadth subequal; metepisternal-metepimeral suture complete though fine laterally. Abdomen with elongate crescent-shaped 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 = 8). Antecostal margin of mediotergite IX angulate, not extended (Fig. 17N ); right paramere narrow, with basal cuff articulating with elongate, whiplike apical extension (Fig. 18G ), six setae along ventral margin to complement to longer apical setae; left paramere narrow basally, evenly narrowed to whiplike apex; aedeagal median lobe robust, broadest medially basad apex of ostial opening, apex subparallel dorsoventrally beyond ostium, with apical face somewhat flattened (Fig. 17M ); aedeagal median lobe internal sac with broad, basal dorsal plate and a large field of macrospicules apicad the plate, but flagellum and flagellar sheath not present.

Female reproductive tract (n = 1). Bursa copulatrix length subequal to circumference, its surface thin, translucent, slightly wrinkled (Fig. 23C ); spermathecal duct entering near bursa-common oviduct juncture with duct oriented toward right side of bursa; elongate laminar helminthoid sclerite present at base of spermathecal duct; spermatheca of only slightly greater circumference than spermathecal duct, spermathecal gland duct entering at base of spermathecal reservoir; ligular apophysis present on common oviduct; basal gonocoxite 1 with apical fringe of two setae laterally, a very small setae may be present immediately mesad, and several smaller setae along medial margin (Fig. 24C ); medial margin bearing a dense field of 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 0.6 × medial length; two gracile lateral ensiform setae of moderate length present.

Types - Holotype male (MNHN): NEW CALEDONIA / Mt Mou summit / 24 May 1984 / G. Monteith & D. Cook // Q.M. Berlesate 659 / 22.04S X 166.21E / Rainforest, 1200 n / Litter // QUEENSLAND / MUSEUM LOAN / DATE: Nov. 2003 / No. LEN-1686 (green label) // HOLOTYPE / Mecyclothorax / Mecyclothorax mouensis / B.P. Moore & J.K. / Liebherr 2017 (black-bordered red label).

Paratypes (33 specimens). NEW CALEDONIA: Mts. Koghis, [code PA 58], 22°11'S 166°31'E, 30-viii-1970, Franz (NHMW, 3), ~5 km N Noumea, 550 m el., 22 10.5'S, 166 30.3'E, forest litter, 25-xi-2009, Schuh (NHMW, 1), forest, 520 m el., 22°10.7'S 166°30.3'E, sifted litter, 25-x-2008, Wanat (MNHW, 9), La Roussette, 600 m el., 22°10.8'S 166°30.7'E, sifted litter, 27-x-2008, Wanat (MNHW, 4), track entrance, 500 m el., 22°11'S 166°31'E, berlesate, 06-v-2005, lot 12264, Monteith (QMB, 4), 500 m el., 22°10'S 166°31'E, 26-viii-1978, S. & J. Peck (CNC, 1), 400-500 m el., 22°11'S 166°31'E, primary forest, 18-19-x-1998, Löbl (MBC, 1; MHNG, 6); Mt. Mou, summit, 1200 m el., 22°04'S, 166°21'E, rainforest litter, 24-v-1984, Monteith & Cook (QMB, 2), top camp, 1150 m el., 22°04'S, 166°21'E, berlesate, sieved litter, 27-xii-2004, lot 12013, Monteith (QMB, 2). Non-type female specimen: Forêt Cachée, 250 m el., 22°11.5'S 166°47.2'E, sifted litter, 26-x-2008, Wanat (MNHW, 1).

Etymology.

As in the species above, this species epithet elides the type locality, Mt. Mou, with the genitive, adjectival ending -ensis. As Dr. Barry P. Moore had both diagnosed this species from the following M. kanak through the use of male genitalic characters, and had chosen a holotype specimen, he is given senior author status for this species.

Distribution and habitat.

This species is restricted to the southern portion of Grande Terre, from Mt. Mou on the west, Mts. Koghis north of Noumea, and with a easternmost record from Forêt Cachée based on a single non-type female specimen (Fig. 25 ). Collection localities range 250-1200 m elevation. Given that 24 of the 35 specimens are labeled from Berlese samples or sieved litter, and another 7 specimens (1, S. & J. Peck, CNC; 6, Löbl, MHNG) were collected by coleopterists studying the microcoleopteran litter fauna, it can be concluded that this species occupies the ground-level litter layer.

Figures

Figure 2. Thoracic structures of Mecyclothorax and Amblytelus spp. A-B. Pronotum, dorsal view: A, M. laterorectus; B, M. mouensis. C-F. Prosternum, ventral view: C, M. fleutiauxi; D, M. curtus; E, M. blackburni; F, M. moorei. G-J. Elytral apices, dorsal view: G, M. fleutiauxi; H, M. laterorectus; I, M. lissus; J, A. curtus. K-L. Elytral lateral margin showing eighth stria, lateral view: K, M. ambiguus; L, M. blackburni. Abbreviations include: aag, anteapical groove; acc, accessory elytral dorsal setae in interval 5; as, apical elytral seta; ca, carina laterad stria 7; ls, lateral elytral setae; ri, ridge mesad stria 8; sa, subapical elytral seta; sas, subapical sinuation of elytron; scs, supracarinal elytral setae; 8, medial portion of stria 8.

Figure 3. Thoracic structures of Mecyclothorax spp. A-B. Lateral view of elytral epipleuron and meso-and metapleurites: A, M. laterorectus; B, M. fleutiauxi. C-D. Metathoracic flight wing: C, M. punctipennis, showing fully developed flight wing folded under elytron; D, M. lissus, stenopterous wing rudiment that extends beyond metanotum, rudimentary wing venation present at base of strap. Abbreviations include: mms, mesepisternal-mesosternal suture; msp, mesepimeron; mst, mesepisternum; mtp, metepimeron; mtt, metepisternum.

Figure 17. Male aedeagal median lobe and parameres, and ring sclerite-mediotergite plus antecostal margin, tergite IX-of Mecyclothorax (Phacothorax) spp.: A-B, M. plurisetosus, right view, dorsal view in situ (Aoupinie); C-D, M. megalovatulus, right view, dorsal view of righ sclerite (Mt. Panie); E-F, M. octavius, right view, dorsal view in situ (Me Maoya); G-H, M. laterovatulus, right view, dorsal view in situ (Aoupinie); I-J, M. manautei, right view, dorsal view in situ (Mt. Humboldt, 1400 m); K-L, M. paniensis, right view, dorsal view in situ (Mt. Panie); M-N, M. mouensis, right view, dorsal view in situ (Mt. Mou). See Table 2 for abbreviations.

Figure 18. Paired left (above) and right (below) parameres of Mecyclothorax (Phacothorax) spp. (ectal view): A, M. plurisetosus; B, M. megalovatulus; C, M. octavius; D, M. laterovatulus; E, M. manautei; F, M. paniensis; G, M. mouensis.

Figure 20. New Caledonian Mecyclothorax (Phacothorax) spp., dorsal view: A, M. manautei; B, M. paniensis; C, M. mouensis; D, M. kanak (Mt. Humboldt, 580 m); E, M. kanak (Mt. Humboldt, 630 m); F, M. kanak (Mt. Dzumac); G, M. kanak (Col de Yate); H, M. picdupinsensis.

Figure 23. Female reproductive tract, gonocoxites and associated laterotergites, Mecyclothorax (Phacothorax) spp: A, M. manautei; B, M. paniensis; C, M. mouensis; D, M. kanak (Mt. Dzumac; common oviduct artificially darkened to show configuration); E, M. kanak (Pic du Grand Kaori); F, M. picdupinsensis. See Table 2 for abbreviations.

Figure 24. Left female gonocoxa of Mecyclothorax (Phacothorax) spp., ventral view: A, M. manautei; B, M. paniensis; C, M. mouensis; D, M. kanak; E, M. picdupinsensis. See Table 2 for abbreviations.

Figure 25. Geographical distributions of Mecyclothorax (Phacothorax) spp. (asterisked locality attributed to M. mouensis based on non-type female specimen).