Meonochilus Liebherr & Marris

Liebherr, James K., 2011, Cladistic assessment of subtribal affinities within the tribe Moriomorphini with description of Rossjoycea glacialis, gen. n. and sp. n. from the South Island, and revision of Meonochilus Liebherr and Marris from the North Island, New Zealand (Coleoptera, Carabidae), ZooKeys 147, pp. 277-335 : 300-303

Meonochilus Liebherr & Marris

Meonochilus Liebherr and Marris, 2009: 7 (type species Tarastethus amplipennis Broun, 1912, by original designation

Diagnosis.

Among Moriomorphini , species of Meonochilus uniquely display the combination of a single, posterior supraorbital seta, glabrous pronotal basal angle and a lateral pronotal seta that is situated on the lateral portion of the pronotal disc, well separated from the lateral depression in individuals of all species except Meonochilus bellorum , sp. n., within which the seta is separated from the lateral depression by a distance equal to the diameter of its articulatory socket. The pronotal median base is distinctly punctate, and the basal and lateral margins of the elytra are joined at a rounded to subangulate humerus. There may be either one or two dorsal elytral setae, the basal seta always present, the apical seta, in the third setal position of interval 3, present only in individuals of Meonochilus bellorum . The eighth elytral interval is not subapically carinate, but it may be convex dorsad the subapical sinuation. Possession in the males of apically setose aedeagal parameres, the ventral or right of which also exhibits multiple elongate setae along its ventral margin (Fig. 1D, 2A, 2F, 2G, 6) establishes membership for this genus in subtribe Amblytelina under the cladistic hypothesis presented above.

Description.

Headcapsule narrow relative to convex margins of pronotum and inflated elytra; frontal grooves distinctly incised and divergent posterad frontoclypeal suture, ended mesad compound eye, in some individuals shallowly continued posteriorly to shallow groove that marks juncture between ocular lobe and gena. Antennae with shafts of basal three antennomeres glabrous, scape with large medioapical seta and shorter ventroapical seta, antennomere 2 with ventroapical seta, and antennomere 3 with apical ring of setae; antennomere 4 with apical ¾ covered with fine setae, and antennomeres 5-11 completely setose; antennal segments submoniliform to moderately elongate, length of antennomere 9 1.6 –2.0× maximum breadth (though Meonochilus spiculatus deviates by having the antennae longer, with length of segment 9 2.3 × its breadth). Labrum transverse, anterior margin 6-setose, broadly and shallowly emarginate, the emargination depth no more than 0.07 × distance between lateral labral apices. Mandibles moderately elongate, their length approximately twice the distance from dorsal condyle to anterior labral margin (mandibles in closed position), apices acute, right mandible with blunt anterior retinacular tooth near apical 1/3 of length, mandibular scrobe bordered ventrally by explanate, translucent margin that is broadest in basal ¼ of length. Maxillary stipes 3-setose, a longer ventral seta plus shorter dorsal seta near base and a third seta medially; lacinia with hook-like apex, apex of galea tightly rounded, subacuminate, maxillary palps glabrous except for a short medial seta at apex of penultimate palpomere, and very short trichoid sensilla covering surface of fusiform, dorsoventrally flattened apical palpomere. Labium with bisetose glossal sclerite that is narrowed lateroapically; paraglossae glabrous, elongate, their apex extended 1/3 their length beyond apical margin of glossal sclerite; penultimate labial palpomere bisetose on medial edge, apical palpomere apparently glabrous, but covered with very small trichoid sensilla. Mentum bisetose, transverse, breadth approximately 3 × longitudinal distance from base to apex of lateral lobes; mentum tooth well developed, varying in shape from broadly rounded in Meonochilus bellorum , to tightly rounded, and variable within species, to acute in some individuals; mentum setae set in broad shallow lateral depressions; submentum 4-setose. Pronotum quadrate to transverse in overall dimensions, the lateral margins broadly convex, basolateral margins either straight or indistinctly sinuate anterad the projected, denticulate hind angles; median base with distinct, isolated punctures, the surface between punctures smooth; mediobasal marginal bead present only in Meonochilus bellorum , absent in other species; sparsely punctate to smooth laterobasal depressions distinctly margined posteriorly by well-developed bead that is continuous with basolateral marginal bead inside hind angles; median longitudinal impression distinctly, broadly impressed, anterior transverse impressions broadly shallow, indistinct especially laterally where they are absent near rounded, little-projected front angles; lateral marginal depression narrow in apical half, broader near basal angles, variably translucent depending on sclerotization and melanization of specimen; prosternal process glabrous, unmargined, the posterior surface convex. Elytra fused along suture, subglobose, the disc elevated relative to base and lateral margins; scutellum broader than long; parascutellar striole short, deep, isolated from first or sutural stria; parascutellar seta present; basal elytral groove continuous laterad the scutellar interval, continuous with lateral elytral margin at rounded to subangulate humerus; a single dorsal elytral seta in third interval near 1/3 elytral length, except for Meonochilus bellorum with a second seta just posterad elytral midlength; lateral elytral setae in two groups, an anterior series of 7 (less commonly 6 or 8) setae, and a posterior series of 6 (rarely 5) setae; apical elytral seta present in apex of seventh stria, subapical seta absent (Fig. 11B) except for Meonochilus bellorum with both setae present (Fig. 11A); subapical sinuation shallow and broad viewed dorsally, the elytral plica well developed, internal, not meeting apicolateral elytral margin. Mesepisternum punctate, from 8-25 punctures along dorsal portion of surface. Metepisternum short, anterior margin longer than lateral margin; metepisternal-metepimeral suture a distinct line in Meonochilus bellorum , Meonochilus rectus and Meonochilus spiculatus , an incomplete line, absent laterally in Meonochilus eplicatus and Meonochilus placens , and a broad indistinct depression in Meonochilus amplipennis . Metathoracic flight wings vestigial, the wing rudiment not extended beyond posterior margin of metanotum. Abdomen with visible ventrites 3-5 bearing 1-2 distinct longitudinal impressions laterally each side; apical ventrite of male with 2 larger setae, one each side (incorrectly reported as 4 setae, 2 each side by Liebherr and Marris, 2009: 9), except for Meonochilus bellorum within which the 2 larger setae are accompanied by 2 shorter subapical setae medially; apical ventrite of female with four setae, two each side, plus 4 medial subapical setae arranged trapezoidally with the shorter parallel anterad. Legs with generalized setation; profemur glabrous anteriorly; mesofemur bisetose anteriorly; mesotibia and metatibia with diffuse lateroapical setal fields, the field arranged in 4 irregular transverse rows on mesotibia, in 4-7 irregular rows on metatibia (least developed in Meonochilus bellorum , within which transverse rows may be indicated by only 1 or 2 setae); metacoxa bisetose, the two setae lateral; metafemur bisetose anteriorly; tarsomeres glabrous dorsally; tarsomeres I–IV broadened apically, the dorsal surface broadly convex with fine lateral grooves each side; female protarsomere 4 with broadly elongate apical lobes, lateroapical lobe length 2 × dorsomedial length of tarsomere, medioapical lobe length 3 × dorsomedial length; male protarsomere 4 lobes of similar breadth but longer, lateroapical lobe 3 × dorsomedial tarsomere length, medioapical lobe 4 × dorsomedial length; male protarsomeres I–III with biseriate, ventral squamose setae, 5-6 paired setae on I, 4-5 on II, and 4 on III, ventral surface of each lobe on protarsomere 4 covered each side with 4-5 longitudinal series of long silky setae, the apical setae extended to apical ¼ of tarsomere 5; claws of protarsomere 5 acuminate, ½ length of tarsomere; mesotarsomeres 1-5 relatively similar in configuration to those of protarsus, though each segment shorter overall; mesotarsomere 4 lobate, lateral lobe longer, length 3 × mediodorsal tarsomere length. Microsculpture generally reduced; vertex shiny, obsolete transverse mesh microsculpture traceable over portions of medial surface (best developed in Meonochilus amplipennis ); pronotal disc shiny, microsculpture generally obsolete, small areas of reduced transverse mesh microsculpture may be visible in some individuals; pronotal median base glossy, smooth between distinct punctures; laterobasal pronotal depression glossy, indistinct isodiametric sculpticells may be visible in the irregular wrinkles of surface; elytral microsculpture most evident, though still much reduced, in association with striae and punctures, elytral intervals generally glossy, though elongate transverse mesh microsculpture is present on intervals in Meonochilus amplipennis ,and in some individuals of Meonochilus eplicatus .

Male genitalia.

Aedeagus with basal bulb closed, a variously developed sagittal crest present, orientation in repose such that anatomical right side is ventral (Fig. 2A, 2B, 2F, 2G, 16); right or ventral paramere narrow, length ranging from 0.50 –0.80× distance from parameral articulation with median lobe to external face of apex; left or dorsal paramere broader in basal half and narrowed apically, its length 0.5 –1.0× distance from parameral articulation to external face of apex; both parameres setose, the right paramere bearing setae broadly distributed over apical half of ventral edge and surrounding parameral tip, the left with 2-3 larger apical setae accompanied by 0-3 smaller setae.

Female reproductive tract.

Gonocoxae bipartite, the basal gonocoxite bearing a lateroapical series of 1-3 setae (always more than 1 seta on at least one gonocoxa), and a series of much smaller setae on the mesal surface; apical gonocoxite with 2 lateral ensiform setae, a single dorsal ensiform seta that is near the dorsomedial surface of the coxite, and an apical sensory furrow bearing 2 nematiform setae; bursa copulatrix columnar in shape, without helminthoid sclerite near the junction with the common oviduct; spermatheca with appended spermathecal gland; membranous ramus present mesad base of basal gonocoxite 1.

Distribution and Habitat.

Species of Meonochilus are restricted geographically to the North Island of New Zealand. Though specific forest habitats recorded for the various species may differ, nearly all specimens of Meonochilus with recorded ecological data have been collected from ground-level microhabitats. These collecting events include activity-based pitfall trapping, and discovery of specimens in terrestrial situations such as under logs or stones, in leaf litter, or along a stream. Though recorded collections include only a few specifically mentioning collecting at night, present evidence suggests that Meonochilus beetles do not climb on vegetation or vertical tree trunks at night, and thus they differ in their behavior from species of Molopsida spp. wherein individuals can be found walking on the bark of upright trees as well as downed logs after dark.

Key to Species for Adults of Meonochilus Liebherr and Marris