Mecyclothorax medioconstrictus Liebherr, 2017

Liebherr, James K., 2017, Review of Mecyclothorax Sharp (Coleoptera: Carabidae: Moriomorphini) from Papua New Guinea, with Descriptions of Five New Species, The Coleopterists Bulletin 71 (4), pp. 679-703 : 687-688

4. Mecyclothorax medioconstrictus Liebherr , new species ( Figs. 3 , 32 )

Diagnosis. As noted above, this species and M. baehri are the only two Mecyclothorax species from Papua New Guinea characterized by a quadrisetose pronotum, three dorsal elytral setae, and presence of both subapical and apical elytral setae. Both species comprise large-bodied beetles — the holotype of this species has a standardized body length 5.0 mm — that exhibit a medially constricted body form. The pronotal base for M. medioconstrictus is relatively narrow, and the elytral lateral margins are narrowly curved posteriorly laterad and behind the humerus ( Fig. 3 ). This species can be diagnosed from M. baehri by the indistinctly punctate pronotal median base versus deeply and distinctly punctate base in M. baehri , and the isodiametric mesh microsculpture on the discal elytral intervals versus the transverse mesh microsculpture in M. baehri .

Description. Head: Frons broadly convex and bordered by shallow, moderately broad, subparallel frontal grooves that extend anteriorly from immediately mesad anterior supraorbital seta, are deepest at juncture with shallow frontoclypeal suture, and extend onto basolateral reaches of clypeus; eyes small in diameter, moderately protruding on an ocular lobe that obtusely meets gena behind the eye ( Fig. 3 ), ocular ratio = 1.50, ocular lobe ratio = 0.81; 3 rd antennomere largely glabrous, though several small setae present basad apical setal ring; antenna moderately elongate, antennomere 9 length 2.1X maximal breadth; anterior labral margin broadly, moderately concave; mandibles of moderate length, distance from dorsal condyle to apex 1.82X distance from condyle to anterolateral margin of labrum; vertex with broad, shallow, transverse depression, or neck, behind eyes; mentum tooth obtuse, apex broadly rounded; ligular apex truncate, broad, 2 ligular setae well separated, paraglossae thin and only slightly extending beyond ligular margin. Pronotum: Narrow, basally constricted, MPW/PL = 1.19, MPW/BPW = 1.48; pronotal lateral seta set on disc 2 setal diameters inside lateral marginal depression; hind angle a distinct, obtuse denticle with lateral margins on the denticle subparallel each side of pronotum, hind seta at or just before obtuse hind angle; median base slightly depressed relative to disc, sparsely, minutely punctate, with 14–16 small punctures each side; median longitudinal impression finely and narrowly impressed at front of median base, shallow and irregular on pronotal disc; anterior transverse impression narrow, finely impressed to border broadly convex anterior callosity, lateral impression deeper and more well defined in lateral 2/3 of length to front angle; front margin with indistinct, narrow convexity medially, though the marginal impression too shallow to call the convexity a marginal bead; front angles not protruding, tightly rounded; lateral marginal depression narrow at position of lateral seta, narrowly lined with microsculpture at depth, broader with irregular transverse wrinkles just anterad hind angle; laterobasal depression a widening of lateral marginal depression inside basal denticles, its medial surface roughened due to presence of 7 punctures; prosternum with distinct anteapical furrow, groove smooth, deep laterally, shallower and broader ventromedially; prosternal process convex anterad procoxal cavities, shallowly bisulcate ventrally between coxae; proepimeron bordered anteriorly and posteriorly by smooth grooves. Elytra: Ellipsoid, humeri narrowly rounded posterad the slightly recurved basal elytral groove, MEW/EL = 0.73, maximum width slightly behind midlength; parascutellar seta present; scutellum narrowly triangular, ratio of width at transverse groove/median length = 1.14; parascutellar striole a continuous shallow groove with 3–4 punctures; striae 1–4 deep, continuous on disc, 4 th striae distinctly punctate, inner striae nearly smooth; stria 5 a series of isolated punctures, stria 6 evidenced by shallow elongate impressions, stria 7 represented by sporadic, shallow, rounded impressions; striae 2–7 reduced on apex, only sutural stria deep and smooth, stria 2 shallow and irregularly punctate, stria 7 impressed in vicinity of subapical seta, striae 8 smoothly and deeply impressed at midlength; lateral marginal depression narrow, margin beaded throughout length; subapical sinuation broadly and shallowly impressed, elytral epipleuron narrowly visible in anterior half of sinuation; lateral elytral setae 7 + 6–7. Mesepisternum: With nine dimpled impressions in 1–3 dorsoventral rows; metepisternal maximum width/ lateral length = 0.65; metasternal process acute, apex tightly rounded, margin broadest and most convex medially; metathoracic wings vestigial, apex not extending beyond posterior margin of metanotum. Abdomen: Ventrites 1 and 2 separated laterally by anteriorly sinuous suture, surface of ventrite 2 depressed within convex sinuosity; suture between ventrites 2 and 3 shallow but traceable laterally; broad shallow depressions present laterally on ventrites 3–6. Microsculpture: Reduced on head, frons glossy, vertex with shallow, transversely stretched sculpticells; pronotal disc covered with shallow elongate transverse mesh, sculpticell breadth 3–4X length, mixed with transverse lines; pronotal base with slightly transverse mesh between punctures; elytral disc with transversely stretched isodiametric mesh, apex with shallow isodiametric mesh, sculpticells flat; metasternum with welldeveloped transverse mesh; lateral portions of basal abdominal ventrites with swirling isodiametric and transverse sculpticells. Coloration: Head capsule piceous, clypeus and mandibles rufopiceous; antennae flavobrunneous, antennomeres 4–11 with piceous cast; pronotal disc piceous, anterior and posterior margins narrowly dark rufous; elytral disc piceous, sutural interval and lateral elytral margins concolorous, apical margin from posterior setae of lateral elytral setal series narrowly rufobrunneous; proepipleuron, proepisternum, elytral epipleuron, and metepisternum piceous; abdomen rufopiceous with ventrites 3–5 amber brunneous along posterior margins, apical ventrite 6 with apical third rufoflavous; femora dark rufous, tibiae dark rufous with piceous cast.

Female Reproductive Tract. Based on external anatomical characters, this species exhibits a sistertaxon relationship with M. baehri in a cladistic analysis including eight of the 11 Papuan New Guinea species reviewed here, plus 50 other taxa including Mecyclothorax species from throughout the generic distribution and moriomorphine outgroups (unpublished data). As such, the generic combination with Mecyclothorax is substantiated without the necessity to dissect the unique female holotype for assessment of internal female reproductive tract characters. Nonetheless, the specimen was relaxed in warm water, allowing slight eversion of the gonocoxae, thereby permitting the following character assessments; basal gonocoxite 1 with 3 apical fringe setae and larger apicomedial seta present (see Figs. 29–31 for homologies); apical gonocoxite 2 broad basally, with base extended by lateral apodeme; apical gonocoxite 2 with 2 lateral ensiform setae present, the setae less than 0.4X the gonocoxite length and situated on the lateral margin of the gonocoxite; apical nematiform setae present in fossa situated less than 0.25X coxite length from the apex.

Holotype. Female ( EMEC, for deposition in NMNHS): MT FUGILIL / summit 3450 m. / 29.ix.75 / P. BERON // British Speleological / Expedition to Papua / New Guinea 1975 // HOLOTYPE / Mecyclothorax / medioconstrictus / J.K. Liebherr 2017 [black-bordered red label]. This specimen was part of the Barry Moore personal collection of carabid beetles transferred to the Essig Museum of Entomology ( EMEC). The specimen no doubt comprised part of a loan that resulted in descriptions of three cave species based on the British Speleological Expedition ( Moore 1977). As such, it was returned to the EMEC for accessioning and will be forwarded to the National Museum of Natural History ( NMNHS, Sofia, Bulgaria) for permanent deposition .

Etymology. The adjectival species epithet, medioconstrictus , denotes the hourglass body shape of the adults of this species, with their broad head, cordate pronotum, and ellipsoid elytra ( Fig. 3 ).

Distribution and Habitat. The elevation of the Mt. Fugilil summit ( Fig. 32 ) was recorded as 3,450 m by P. Beron for the holotype specimen collected 29.ix.1975. Shear (1980) cites the summit’ s elevation as 3,050 m for the holotype of Malayothrix papuana Shear ( Diplopoda: Metopidiotrichidae ), also collected by Beron on 29.ix.1975. The geographic coordinates for the summit ( National Geospatial Intelligence Agency 2017) — 5° 11.62´S 141° 20.43´E — are associated with an elevation of 2,506 m ( Google Earth 2017). The highest point in the vicinity of these coordinates is at 2,782 m elevation, suggesting a tentative summit elevation for this massif. Regardless of elevation, the area surrounding Mt. Fugilil is forested, supporting this species’ occupation of montane forest habitat.

Figures

Figs. 1–4. Mecyclothorax species, dorsal habitus. 1) M. kavanaughi; 2) M. baehri; 3) M. medioconstrictus; 4) M. andersoni. Range of standardized body lengths (in mm) and setal formulae (see text) for number of supraorbital setae each side, number of pronotal setae each side, number of dorsal elytral setae each elytron, and number of setae at the apex of each elytron are indicated.

Fig. 32. Localities in Papua New Guinea from which Mecyclothorax spp. were collected and the particular species collected at each locality. 1 = Mt. Capella — M. baehri; 2 = Mt. Fugilil — M. brispex and M. medioconstrictus; 3 = Kubor Range — M. kubor; 4 = Mt. Wilhelm — M. sedlaceki; 5 = Finisterre Range — M. kavanaughi; 6 = Mt. Missim — M. gressitti; 7 = Mt. Kaindi, Edie Creek and Bulldog Road — M. andersoni, M. cuccodoroi, and M. loebli; 8 = Mt. Amungwiwa—M. amingwiwae.

Figs. 29–31. Mecyclothorax species, female gonocoxae, right side, ventral view. 29) M. andersoni; 30) M. brispex; 31) M. gressitti. Abbreviations aredefined in Table 1; scale bars = 0.05 mm.