Mecyclothorax mahatahi, Liebherr, James K., 2012

Liebherr, James K., 2012, The first precinctive Carabidae from Moorea, Society Islands: new Mecyclothorax spp. (Coleoptera) from the summit of Mont Tohiea, ZooKeys 224, pp. 37-80: 51-53

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scientific name

Mecyclothorax mahatahi

sp. n.

Mecyclothorax mahatahi   ZBK   sp. n.


This species shares reduced setation, setal formula 1111 (Fig. 3A), with four other species in the group; Mecyclothorax sabulicola   Britton, Mecyclothorax ataraensis   Perrault, Mecyclothorax taiarapu   Perrault, and Mecyclothorax cupripennis   Perrault. Of these, Mecyclothorax cupripennis   shares reduced microsculpture with this species, the pronotal disc lacking any discernible sculpticells. The two species differ in elytral microsculpture. This new species is characterized by a glossy elytral integument, with only sporadic small patches of indistinct isodiametric sculpticells in transverse rows, whereas Mecyclothorax cupripennis   is characterized by presence of a more regular, though shallow, transverse mesh on the discal elytral intervals; the sculpticells consistently visible outside the reflection of bright, direct microscope light. Body size is similar for the two species; standardized body length of the new species is 3.7 mm, that for Mecyclothorax cupripennis   3.5 mm (measurement made on male specimen, CUIC).


Head capsule withsinuous frontal grooves, closest at frontoclypeal suture and defining a lyre shape, adjacent area of frons broadly depressed mesad anterior margin of eye, base of frontal groove separated from eye by a broad, low convexity; dorsum of head flat on frons in lateral view, neck convex; anterior supraorbital seta absent, posterior seta situated at dorsal terminus of broad shallow groove between ocular lobe and gena; eyes and ocular lobe little protruded, posterior portion of lobe meeting gena at about 135˚ angle; compound eye with 10 ommatidia on horizontal diameter defined by lower margin of antennal articulatory socket; ocular ratio 1.37, ocular lobe ratio 0.67; labral anterior margin broadly, shallowly emarginate ¹⁄₁₂ length; antennomeres 1-3 glabrous escept for apical setae; antennae moniliform, antennomere 8 length subequal to greatest width; mentum tooth with sides defining acute angle, apex tightly rounded. Prothorax cordate, disc convex, basolateral margins convergent anterad acute, projected hind angles, MPW/BPW = 1.53, MPW/PL = 1.18 (Fig. 3A); median base slightly depressed relative to disc, moreso laterally, with ~13 larger isolated punctures each side; basal margin broadly convex between laterobasal depressions; median longitudinal impression absent on basal half of disc, obsolete and traceable anterad due to indistinct transverse wrinkles at position of impression; anterior transverse impression shallow, broad, smooth medially, finely incised in lateral ⅔ of breadth; anterior callosity slightly convex, smooth; front angles slightly protruded, tightly rounded, APW/BPW = 0.99 (n = 1); lateral marginal depression very narrow, slightly broader at front angle, edge beaded throughout; laterobasal depression a deep continuation of lateral depression, bordered anteromesally by punctate median base, and laterally and posteriorly by raised marginal bead at hind angle; proepisternum with 5 minute punctures along hind margin; prosternal process narrowly depressed medially, broadly upraised each side between coxae. Elytra subovoid, MEW/HuW = 2.14 (n = 1), middle of disc flat, intervals 2-8 increasingly depressed to near vertical juncture with lateral marginal depression; basal groove distinctly curved forward to angulate humerus that lies distinctly anterad base of scutellum; parascutellar seta present, immediately adjacent to parascutellar striole; parascutellar striole finely incised, smooth anterad, 1-2 small punctures near apex; sutural interval coplanar with stria 2; striae 1-6 shallow, complete, with very small punctures at strial depth, the punctures less distinct in lateral striae; sutural stria 1 deepest at elytral apex, striae 2, 3, and 7 shallow but complete apically; discal elytral intervals slightly convex; interval 8 narrowly subcarinate laterad apex of stria 7, slightly more convex than more mesal intervals; a single dorsal elytral seta at 0.24 × elytral length set in small setal depression spanning less than half of interval 3; apical elytral seta present, subapical seta absent; lateral elytral setae 7 + 6; elytral marginal depression moderately narrow, margin upraised near humerus, beadlike only near subapical sinuation; subapical sinuation deep, abruptly excavate anteriorly. Mesepisternum punctate anteriorly, with ~14 punctures in 2-3 rows; metepisternum short, anterior and mesal edges subequal, width to length ratio 0.8; metepisternum separated from metepimeron by a distinct suture. Abdomen irregularly wrinkled on lateral portions of visible ventrites 1-4, indistinct rounded depressions laterally on ventrites 4-6; suture between ventrites 2 and 3 effaced laterally. Legs with short, stout tarsomeres, metatarsomere 4 overall length subequal to breadth, length including apical lobes 1.2 × median tarsomere length; metatarsomere 4 with both apical and subapical setae; metatarsal dorsolateral sulci deep, lateral, median broadly convex. Microsculpture of frons obsolete, surface glossy, indistinct transverse mesh in deepest portions of frontal grooves; pronotal disc glossy with indistinct elongate transverse mesh-sculpticell breadth 3 –4× length-visible near edge of areas of reflected light; pronotal median base glossy except for obsolete transverse mesh near discal margin; elytral disc mostly glossy, patches of transverse mesh, breadth 3 –4× length, visible near striae; elytral apex glossy, transverse mesh visible at apical margin; metasternum with evident transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse sculpticells. Coloration of head capsule a glossy rufopiceous; antennomere 1 flavous, 2-3 rufoflavous, 4-11 rufobrunneous; pronotal disc glossy rufopiceous, pronotal lateral margins concolorous, base and apex slightly paler at edge; proepipleuron rufopiceous along edge, mediolongitudinally rufoflavous, rufobrunneous along margin with rufobrunneous proepisternum; elytral disc glossy rufopiceous; scutellum and base of sutural interval dark rufous, apex of sutural interval broadly rufobrunneous; elytral margin concolorous with disc near elytral base, lateral marginal depression paler, rufoflavous behind; elytral apex broadly, slightly paler, brunneous; elytral epipleuron paler, rufoflavous dorsally, rufobrunneous ventrally to match metepisternum; abdominal visible ventrite 1 rufobrunneous; ventrites 2-3 rufopiceous medially, brunneous laterally along with ventrites 4-6; apical ventrite 6 rufoflavous in apical ⅓; metafemur rufoflavous; metatibia rufoflavous with brunneous cast.

Female reproductive tract. The unique female holotype was not dissected.

Holotype female (MNHN), labeled: FRENCH POLYNESIA: Moorea / Tohiea, off trail beneath ridge / 25-ix-2009 el. 1145 m C. Ewing / -17.55152 -149.82147 pyr. fog / unknown tree MBIO5551 // HOLOTYPE / Mecyclothorax / mahatahi / J.K. Liebherr 2012 (black-bordered red label).


The species epithet is a compounding of maha, Tahitian for the number four, and tahi, Tahitian for one (Wahlroos, 2002), indicative of the reduced setation in this species resulting in the setal formula of 1111. As tahi is indeclinable, the epithet is to be treated as a noun in apposition.

Distribution and habitat.

The unique specimen was collected in pyrethrin fog sample of a mossmat in association with one specimen of Mecyclothorax perraulti   .