Mecyclothorax laterobustus 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 : 16-17

1. Mecyclothorax laterobustus Liebherr sp. n. Figures 5E , 9A , 10A-B , 12A , 13A , 14

Diagnosis.

These beetles are very robust, with a broad pronotum and broadly convex elytra (Fig. 9A ). The pronotal base is broad, with MPW/BPW = 1.30-1.32, and the hind angles are projected, with the pronotal lateral margin concave just before the angle. Only the posterior supraorbital seta is present, and the pronotum is glabrous. Elytral striae 1-5 are well developed basally, with striae 3-5 deeper than those of individuals of the similar appearing M. laterosinuatus and M. laterorectus (Fig. 9B-C ). Standardized body length 4.1-4.4 mm. Chaetotaxy -/+//-/-//+/2/+/+.

Description

(n = 5). Head capsule broad, eyes moderately convex, ocular lobe meeting gena at very obtuse angle; 16 ommatidia along horizontal diameter of eye; ocular ratio 1.33-1.42, EyL/EyD = 2.34-3.0; frontal grooves deep, arcuately convergent and deepest just posterad clypeus, briefly and shallowly extended onto clypeus; mandibles moderately elongate, mandibular ratio 1.67; ligular anterior margin rounded to ligular seta, concave between setae, the two setae separated by two setal diameters; paraglossae thin, extended as far beyond ligular margin as their basal length to margin; antennae moderately elongate, antennomere 9 length 2.0 × maximal breadth; antennomere 3 glabrous except for apical ring of setae. Pronotum moderately constricted basally, with obtuse-rounded hind angles and lateral margins briefly sinuate anterad angles (Fig. 9A ); MPW/BPW = 1.30-1.32, MPW/PL = 1.19-1.22; front angles protruded anteriorly, but anterior margin narrowly approaching head capsule, APW/BPW = 0.69-0.71; basal margin broadly convex, beaded from just mesad deep, longitudinal laterobasal depression to and around obtuse-rounded hind angle; median longitudinal impression deep and narrow on disc, broader and shallower approaching base, absent anterad very shallow anterior transverse impression; proepisternum separated from prosternum by a very shallow groove anteriorly, but with a deep, slightly punctate groove ventrally; prosternal process deeply and narrowly depressed between procoxae, that depression extended 1/3 distance toward anterior prothoracic margin. Elytra broadly ovoid, humeri broad, humeral angle obtusely rounded laterad pronotal hind angles; MEW/EL = 0.87-0.93; basal groove evenly arcuate from scutellum to humeral angles, with depression at bases of sutural and elytral striae 4-5; sutural stria deep throughout length, stria 2 obsolete though traceable, stria 3 somewhat deeper, striae 4-5 deep in basal half, striae 6-7 obsolete; only sutural stria and stria 8 evident apically, elytra appressed and conjoined apically, sutural intervals narrower and upraised at apex. Pterothoracic mesepisternal anterior furrow with 6-7 deep punctures; mesosternal-mesepisternal suture complete (as in Fig. 3A ); metepisternum maximum width/lateral length = 1.0; metepisternal-metepimeral suture incomplete, shallower and incomplete laterally. Abdomen with deep crescent-shaped depression along suture between first and second ventrite, second ventrite depressed within 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 a shallow transverse mesh, sculpticells twice as broad as long, these mixed with isodiametric sculpticells on vertex; pronotal disc and base covered with elongate transverse mesh plus transverse lines, surface iridescent; elytral iridescent, disc with loose elongate transverse mesh, apex with very elongate transverse mesh, sculpticell breadth 3-4 × length.

Male genitalia (n = 1). Antecostal margin of male mediotergite IX distally angulate, little extended (Fig. 10B ); right paramere very elongate, moderately narrow, with a single seta on dorsal margin distant from two apical setae (Fig. 5E ); left paramere narrow basally, evenly narrowed to a whip-shaped apex, two longer setae at apex; aedeagal median lobe shaft robust, broad dorsoventrally (Fig. 10A ), median lobe apex broad, sides subparallel, with tip broadly rounded; aedeagal internal sac with flagellum, flagellar sheath, and sclerotized dorsal plate.

Female reproductive tract (n = 1). Bursa copulatrix elongate, length more than twice circumference, surface translucent, membranous (Fig. 12A ); spermathecal duct entering near bursa-common oviduct juncture with duct oriented toward right side of bursa, duct longer than spermathecal reservoir; a rounded laminar helminthoid sclerite present at base of spermathecal duct; spermatheca fusiform on narrow duct, spermathecal gland duct entering at base of spermathecal reservoir; basal gonocoxite 1 with apical fringe of two setae near medial margin, a series of small setae lining medial margin (Fig. 13A ); gonocoxite 2 moderately broad basally, basal width about half medial length; two gracile lateral ensiform setae of moderate length present.

Types - Holotype male (MNHN): NEW CALEDONIA / Ningua Res.camp / 12-13Nov 2001 / G.B.Monteith // QM Berlesate 1039 / 21°45 ’Sx166°09’ / Rainforest, 1100m / Sieved litter // QUEENSLAND / MUSEUM LOAN / Date: Nov. 2003 / No. LEN-1686 (green label) // HOLOTYPE / Mecyclothorax / Mecyclothorax laterobustus / J.K.Liebherr 2017 (black-bordered red label).

Paratypes (10 specimens). NEW CALEDONIA: Ningua Reserve, camp, 1100 m el., 21°45'S 166°09'E, rainforest, sieved litter, 12-13-xi-2001, lot 1039, Monteith (QMB, 4), near summit, rainforest, 1300 m el., 21°45'S 166°09'E, berlesate, sieved litter, 13-xi-2001, lot 1052, Monteith (QMB, 3); Plateau de Dogny, rainforest, 910 m el., 21°37'S, 165°53'E, berlesate sieved litter, 16-xi-2002, lot 1085, Burwell (QMB, 3).

Etymology.

The very broad and robust body form of these beetles (Fig. 9A ) suggests the compound, adjectival species epithet laterorobustus.

Distribution and habitat.

This species is known from two localities, Ningua Reserve and Plateau de Dogny (Fig. 14 ), and specimens have been collected from 900-1300 m elevation. The three collecting events are all based on recovering specimens from sieved litter, consistent with an interpretation that these beetles occupy ground-level microhabitats.

Figures

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 5. Paired left (above) and right (below) parameres of Mecyclothorax spp. (ectal view): A, M. blackburni; B, M. storeyi; C, M. amplipennis; D, M. montivagus; E, M. laterobustus. As the aedeagal assembly of M. storeyi males is inverted relative to other Mecyclothorax species (Moore 1984), the configuration of the upper, or right paramere of M. storeyi should be compared to the ventral, or left parameres of the other species, and vice versa.

Figure 9. New Caledonian Mecyclothorax (Phacothorax) spp., dorsal view: A, M. laterobustus; B, M. laterosinuatus; C, M. laterorectus; D, M. fleutiauxi; E, M. jeanneli.

Figure 10. Male aedeagal median lobe and parameres, and ring sclerite-mediotergite plus antecostal margin, tergite IX-of Mecyclothorax (Phacothorax) spp.: A-B, M. laterorobustus, right view, dorsal view in situ (Ningua); C, M. laterosinuatus, right view (Col d'Amieu); D, M. laterosinuatus, right view (Touho TV tower); E, M. laterosinuatus ring, dorsal view; F, M. laterorectus, right view (Mt. Panie); G-H, M. laterorectus, right vew, dorsal view in situ (Mandjelia); I-J, M. fleutiauxi, right view, dorsal view in situ (Mt. Do); K-L, M. fleutiauxi, right view, sac inverted and everted (Me Maoya); M, M. fleutiauxi, right view (Ningua); N-O, M. jeanneli, right view, dorsal view in situ (Mt. Humboldt, 1350 m); P, M. jeanneli, right view (Mt. Humboldt, 1300 m); Q, M. jeanneli, right view, sac everted (Mt. Dzumac); R, M. jeanneli, right view (Riviere Bleue). See Table 2 for abbreviations.

Figure 12. Female reproductive tract, gonocoxites and associated laterotergites, Mecyclothorax (Phacothorax) spp: A, M. laterobustus; B, M. laterosinuatus; C, M. laterorectus; D, M. fleutiauxi; E, M. jeanneli; F, M. plurisetosus; G, M. megalovatulus. See Table 2 for abbreviations.

Figure 13. Left female gonocoxa, ventral view, Mecyclothorax (Phacothorax) spp.: A, M. laterobustus; B, M. laterosinuatus; C, M. laterorectus; D, M. fleutiauxi; E, M. jeanneli; F, M. plurisetosus; G, M. megalovatulus. See Table 2 for abbreviations.

Figure 14. Geographical distributions of Mecyclothorax (Phacothorax) spp.