Platynus (Dyscolus) duportei Liebherr and Ivie, 2021

Liebherr, James K. & Ivie, Michael A., 2021, Two New Platynus Bonelli (Coleoptera: Carabidae: Platynini) from Nevis and St. Kitts, Lesser Antilles, The Coleopterists Bulletin 75 (1), pp. 59-74 : 66-68

Platynus (Dyscolus) duportei Liebherr and Ivie , new species

zoobank.org/ urn:lsid:zoobank.org:act:605A943E-2A25-4840-8740-52FB216F3D0B ( Figs. 2b , 4, 6 )

Diagnosis. This species exhibits a broad, translucent lateral pronotal marginal depression that extends to the projected, narrowly rounded front angle, with the lateral margin only slightly sinuate before the sharp hind angle ( Fig. 4 ). The pronotal median base is depressed relative to the disc, and the laterobasal depressions are deep, with a shallow, oblique linear depression adjacent to the median base, the depression broadly upraised laterally to meet the upraised pronotal lateral margin. The head is gracile and elongate, and the small eyes project slightly beyond the genal curvature; ocular ratio = 1.45. Microsculpture is similar to that of P. racquelae , with the head bearing a shallow isodiametric mesh, and the pronotal disc with elongate transverse sculpticells, breadth 4–5× length. However, the elytral microsculpture is more upraised than observed in P. racquelae , with the transverse microsculpture subgranulose, and the sculpticells a mix of isodiametric and transverse, the breadth of the latter 2× length ( Fig. 6 ). The elytral intervals are moderately convex, the striae well defined, the upraised microsculpture producing a glaucous, piceous sheen to the elytra that contrasts with the glossier, rufopiceous forebody. Standardized body length is 13.7 mm.

Description. Head: Frontal grooves shallow, convergent from anterad supraorbital seta then sinuously curved laterad to meet clypeus; vertex slightly transversely depressed halfway between posterior supraorbital setae and pronotal margin, the depression broad and shallow in lateral view; labrum quadrate, twice as broad as long, with anterior margin straight, 6-setose, 4 smaller setae anteriorly along lateral margin; antennae filiform, scape robust with a single seta anterodorsally, pedicel with single apical seta, and antennomere 3 with apical ring of setae, the segment bowed with lateral concave surface crenulate; antennomeres 4–11 covered with microsetose pelage from basal fifth of antennomere 4, elongate, antennomere 9 length 2.6× maximal breadth; mandibles elongate, length of left mandible measured from anterior condyle 1.95× distance from anterior condyle to anterolateral margin of labrum; mentum with broadly rounded median tooth; submentum bisetose each side. Prothorax: Notum with median disc convexly elevated relative to broad lateral reaches of disc, these bordered laterally by a broad, lateral marginal depression, the pronotal lateral margins moderately elevated, not beaded ( Fig. 4 ); median base margined across width, the bead fine and continuous to hind angles, basal surface with very shallow strigae at juncture with disc; median longitudinal impression fine, continuous from median base to broad shallow anterior transverse impression, shallowly extended beyond impression 1/4 distance to pronotal anterior margin; pronotal anterior margin beaded across breadth, the marginal bead continuous with more elevated margin at front angles; lateral margins slightly sinuate in basal half of pronotum, the margin becoming broader and more elevated from lateral pronotal seta to setose hind angle; prosternum medially flattened anterad procoxal cavities, slightly depressed between coxae, prosternal process glabrous, flattened behind, its lateral margins sharply angled posterad coxal cavities. Elytra: Slightly ellipsoid, basal groove evenly recurved to the narrow humerus, the basal groove convexly meeting the lateral marginal groove; all striae developed, finely incised, the intervening intervals slightly convex; parascutellar striole elongate, smooth, extended from basal groove halfway to anterior dorsal elytral seta; parascutellar seta set just mesad basal juncture of first (sutural) and second striae; laterally, fifth and sixth striae conjoined basally; 3 dorsal elytral setae present, the anterior just mesad stria 3, the posterior 2 laterad stria 2; in addition to the 19 lateral elytral setae, 3 setae present at elytral apex, the apical seta just mesad sutural stria at apex, 2 subapical setae in apical portion of stria 7; subapical sinuation distinctly concave, the elytral apex rounded. Pterothorax: Well developed, metanepisternum moderately elongate, length 2.1× maximal breadth; flight wings with reflexed apex, appearing full, though wing not extended in single female holotype. Abdomen: Ventrites smooth medially, longitudinally wrinkled laterally; ventrite 1 with about 20 distinct longitudinal strigae posterad metacoxa; ventrites 2–6 with diffuse longitudinal wrinkles laterally, ventrites 1–3 connate, not depressed laterally, free ventrites 4–6 with depressed plaques laterally along margin with anteriorly neighboring segment; ventrites 3–5 with base number of single setae each side of midline, but those setae doubled unilaterally on ventrites 4 and 5 (indicating setal instability); apical ventrite with 2 setae each side on female holotype. Legs: Elongate, gracile; procoxa unisetose; profemur with 3 posteroventral setae; mesocoxa with ventral seta and 1 seta on coxal ridge bordering depression that receives femur; mesofemur with 4 posteroventral setae, 6 distal setae on ventral face, and a double row of 12 or more setae on anterior face; metacoxa bisetose, 2 lateral setae present; metafemur with 4–5 posteroventral setae, anteroapical surface glabrous; metatarsomeres robust, moderately broadened apically, with well-developed laterodorsal sulci bordering a broadly convex dorsal surface; metatarsomere 4 short, broad, apically emarginated, outer apical lobe longer, its length along outer apical lobe 1.45× median length; ventral tarsomere surfaces lined laterally with 4 parallel, longitudinal series of fine, elongate setae, these setae longest on outer lobe of mt4; fifth tarsomere glabrous ventrally.

Female Reproductive Tract. The lone female holotype specimen was not dissected.

Holotype. Female ( WIBF, deposited in NMNH): NEVIS: St. John, Figtree / Nevis Peak, 985 m / 17.1495°N. 62.5837°W / 27MAY2017, under moss / R. Henley & W. Smithen // HOLOTYPE / Platynus (Dyscolus) / duportei / Liebherr & Ivie 2019 [blackmargined red label].

Etymology. The species epithet honors a native son of Nevis, Professor Ernest Melville DuPorte (1891–1981), an esteemed insect morphologist who spent his career teaching entomology, genetics, medical entomology and parasitology at McGill University, Montreal. His research contributions focused on the evolutionary origins of structures of the insect head and thorax ( DuPorte 1957, 1962), with his knowledge passed on to students via his Manual of Insect Morphology textbook ( DuPorte 1959).

Distribution and Habitat. Though this species is known only from one individual, the apparently fully-developed wings of the holotype suggest that beetles of this species could fly, at least under conditions in which metathoracic flight muscles were developed (e.g., Schaick Zillesen and Brunsting 1984). Nonetheless, the single record for this species from the highest possible locality suggests that it possesses a very limited ecological preference marginally satisfied by the island of Nevis.

Figures

Figs. 1–2. Federation of St. Kitts and Nevis. 1) Distribution of significant collecting sites/effort, insect survey sites in 2017. Black dots represent collecting sites; gray contours indicate 200-m intervals (St. Kitts) and 61-m intervals (Nevis); black lines indicate National Parks. Source: National Physical Development Plan; 2) Platynus species distributions on St. Kitts and Nevis, extent of Elfin and Sierra Palm Cloud Forest indicated with hatched polygons, 900-m contour indicated with heavy black line, a) Collection sites of P. racquelae, new species (■); type locality along Crater Rim to left, Dos D’ane Pond collecting site to right, b) Collection sites for P. duportei, new

Figs. 3–6. New species of Platynus. 3) P. racquelae, new species, female paratype (WIBF); 4) P. duportei, new species, female holotype (WIBF); 5) P. racquelae, new species, elytral microsculpture, median base of left elytron; 6) P. duportei, new species, elytral microsculpture, median base of left elytron.