Platynus (Dyscolus) racquelae 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 : 62-66

Platynus (Dyscolus) racquelae Liebherr and Ivie , new species

zoobank.org/ urn:lsid:zoobank.org:act:819EC30A-BD57-4922-B8C2-12B4040250F4 ( Figs. 2a , 3, 5 , 7 , 10–11, 14 , 16 , 18–19 )

Diagnosis. Among Lesser Antillean Platynus , individuals of this species uniquely bear more than one pronotal lateral seta in the anterior half of the pronotum (at least unilaterally), with most individuals exhibiting two to four setae anteriorly on each side. Rarely a single seta will be present (observed in 2 of 14 specimens examined), but each of these exhibits two setae on the alternate side. Standardized body length is similarly variable, with body lengths ranging 10.8–14.5 mm. The pronotum is gracile, narrow relative to the elytra ( Fig. 3 ), with MPW/PL ranging 1.16–1.25—slightly broader than the pronotum of P. duportei with MPW/PL = 1.14, and MPW/BPW ranging 1.27–1.39. The elytra are narrowed across the humeri, with the elytral basal groove subangulately meeting the narrow lateral marginal depression on the humerus. The eyes are small, little projected beyond the genal curvature; ocular ratio 1.44. The vertex bears shallow isodiametric microsculpture, the pronotal disc is covered with an elongate transverse mesh, sculpticell breadth 4–5× length, and the slightly convex discal elytral intervals are covered with a regular transverse mesh, sculpticell breadth 2× length ( Fig. 5 ).

Description. Head: Frons longitudinally depressed medially between eyes, frontal grooves extended from posterad anterior supraorbital setae, convergent to just posterad antennal insertion, then divergent to clypeus, the areas between frontal grooves and supraorbital groove extensively, longitudinally wrinkled; antenna filiform, scape moderately robust, with dorsoapical seta, pedicel with anteroapical seta, and antennomere 3 with apical ring of setae only; anterior surface of third antennomere slightly more concave than posterior surface, minute dorsoventral strigae along surface; antennomeres 4–11 moderately elongate, covered with microsetose pelage beginning with basal ¼ of antennomere 4, antennomere 9 length 2.4× maximal breadth; mandibles very elongate, length of left mandible measured from anterior condyle 2.1× distance from anterior condyle to anterolateral margin of labrum; mentum with projected, narrowly acuminate median tooth; submentum bisetose each side. Prothorax: Median disc broadly convex in anterior ¼ of length, median disc bordered laterally at midlength by less convex, broad lateral area that extends to narrow marginal depression ( Fig. 3 ), the pronotal lateral margin narrowly elevated, beadlike outside lateral setal series, more broadly elevated, upraised with a marginal bead approaching hind angle; median base finely margined across width, the bead fine and continuous to hind angles, basal surface covered with fine strigae mesad the laterobasal depressions; laterobasal depressions deepest medially, a convex tubercle between deepest line along median base and upraised pronotal margin; median longitudinal impression fine, continuous from median base to broad, shallow anterior transverse impression, shallowly extended anterad impression 1/3 distance to anterior pronotal margin; pronotal anterior margin beaded across breadth, the marginal bead continuous with more elevated margin at moderately protruded, narrowly rounded front angles; lateral margins distinctly sinuate in basal half of pronotum, hind angles nearly right to obtuse, sharp; prosternum medially flattened anterad procoxal cavities, slightly depressed between coxae; prosternal process glabrous, flattened behind, its lateral margins sharply angled posterad coxal cavities. Elytra: Subquadrate, basal groove evenly recurved to the narrowly rounded humerus, groove may be slightly crenulate at bases of striae; all striae developed, deep and lined with microsculpture, the intervening intervals moderately convex; parascutellar striole elongate, smooth, interrupted apically, extended from basal groove more than halfway to anterior dorsal elytral seta; parascutellar seta set mesad base of first (sutural) stria, stria 2 approaching stria 1 basally but not conjoined; laterally, fifth and sixth stria approaching each other at their bases, but not conjoined; 3 dorsal elytral setae present (or a fourth seta present unilaterally between apical 2 setae; Fig. 3 ), the anterior just mesad stria 3, the posterior 2 (or 3) laterad stria 2, the setae positioned in depressions that span ½ to ¾ of interval; in addition to 19–21 (modally 20) 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 broadly concave, elytral apex broadly rounded, apices not joined at suture. Pterothorax: Moderately developed, metanepisternum moderately broad relative to length, lateral length 1.85× maximal breadth; flight wings reduced in length (relative to fully macropterous species such as P. luciae below), ratio of wing length to elytral length 1.10–1.13 (n = 2), all principal veins developed, but the alar surface foreshortened, wedge cell with incomplete vein approaching MP 3+4 ( Fig. 7 ), oblongum cell incomplete, and radial cell bordered by well-developed RA 3 and a less sclerotized posterior border adjoined to crossvein r4; apical margin of alar surface concave between apex of RA 4 and RP 2. 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 single setae each side of midline; apical ventrite with 2 setae each side in females, 1 seta each side in males. Legs: Elongate, gracile; procoxa unisetose; profemur with 4–6 posteroventral setae; mesocoxa with ventral seta and 1 seta on coxal ridge bordering depression that receives femur; mesofemur with 4–5 posteroventral setae, 6 distal setae on ventral face, and a double row of 20 or more setae on anterior face; metacoxa bisetose, 2 lateral setae present; metafemur with 3–5 posteroventral setae, anteroapical surface glabrous; metatarsomeres 1–4 robust with well-developed laterodorsal sulci bordering a broadly convex dorsal surface, broadened apically, tarsomeres 2–4 triangular; metatarsomere 4 short, broad, apically emarginate, outer apical lobe longer, its length along outer apical lobe 1.4× 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.

Male Genitalia and Testis Condition (n = 1). A single right testis present, consistent with other members of Dyscolus , the associated accessory gland hypertrophied, very large and extended into left side of abdomen; aedeagal median lobe moderately robust, ventral surface slightly expanded near midlength ( Fig. 10 ); basal bulb without sagittal crest; median lobe apex narrowly subtriangular with tightly rounded tip; internal sac without major spiculation (observed in partially everted condition); internal apodeme of abdominal segment VIII narrowly sclerotized, broadly convex ( Fig. 11 ); internal apodeme of abdominal segment IX narrow laterally, asymmetrically broadened distally where left arm of apodeme joins apex.

Female Reproductive Tract (n = 1). Bursa copulatrix columnar, elongate, defined basally by broad microtrichial band ( Fig. 14 ); vagina basad band slightly broadened; spermathecal duct short, joining short fusiform spermatheca, spermathecal gland duct entering at base of spermathecal reservoir; spermathecal gland with elongate reservoir, the reservoir longer than spermathecal gland duct; gonocoxa bipartite, basal gonocoxite with apical fringe of 8–9 setae ( Fig. 16 ); apical gonocoxite subtriangular, narrow basally with subangulate apex, bearing 2 short lateral ensiform setae and a dorsal ensiform seta; apical nematiform setae present in elongate fossa near gonocoxal apex.

Holotype. Male ( WIBF, deposited in NMNH): ST. KITTS: St. John / Capisterre, The Crater Rim / 17.3719°N, 62.8119°W / 01 JUNE 2017, under rock / F. E. Etzler & J. B. Runyon // HOLOTYPE / Platynus (Dyscolus) / racquelae / Liebherr & Ivie 2019 [black-margined red label].

Paratypes. Thirteen females and one male: ST. KITTS: Dos D’ ane Pond / 16FEB-10 MAR 2017 923 m / 17.3576°N. 62.7901W / STK Forestry crew / FIT and Malaise ( CUIC, 2; WIBF, 11; NMNH, 1). The male is deposited in WIBF .

Etymology. This species is named to honor Racquel Williams-Ezquea (1983–2018) for her involvement in the St. Kitts and Nevis biotic survey, during which she enthusiastically coordinated field operations and student participation, inspiring the students’ appreciation for St. Kitts’ biodiversity.

Distribution and Habitat. Though restricted to the highest elevation habitats in St. Kitts, the type series was collected both in the terrestrial microhabitat— under a rock ( Fig. 18 )—and in an FIT/Malaise trap apparatus ( Fig. 19 ). Given the reduced flight wings observed in individuals of this species, it would appear that beetles climbed into the FIT/Malaise trap, presumably indicating a propensity to climb vegetation within the closed canopy forest.

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.

Figs. 7–9. Platynus species, left metathoracic flight wing, ventral view. 7) P. racquelae, new species, paratype female (CUIC); 8) P. luciae male (CUIC); 9) P. luciae female (CUIC). Abbreviations include: CUA1, anterior cubital vein 1; I, island sclerite basad radial cell; mb, median bridge articulation of medial and radial veins; MP1+2, posterior medius branch 1 + 2; MP3+4, posterior medius branch 3 + 4; o, oblongum cell; r, radial cell; r4, radial crossvein 4; RA, anterior radius; RA3 and RA4, anterior radius branches 3 and 4; RP2, posterior radius branch 2; w, wedge cell formed by junctures of anterior cubitus and anterior anal veins.

Figs. 10–15. Platynus species, reproductive structures. Male genitalic structures: 10) P. racquelae, new species, male paratype (WIBF) aedeagal median lobe, right lateral view; 11) P. racquelae, new species, male terminal abdominal segments VIII and IX; 12) P. luciae, male aedeagal median lobe, right lateral view; 13) P. luciae, male terminal segments VIII and IX. Abbreviations for male structures include: is, internal sac of median lobe, partially everted; lp, left paramere; rp, right paramere; sc, sagittal crest of median lobe; VIII, internal apodeme of laterotergites, segment VIII; IX, internal apodeme of laterotergites, segment IX. Female reproductive tract, ventral view: 14) P. racquelae, new species, female paratype (CUIC); 15) P. luciae (CUIC). Abbreviations for female structures include: bc, bursa copulatrix; co, common oviduct; gc1, basal gonocoxite 1; gc2, apical gonocoxite 2; hg, hindgut; lo, lateral oviduct; mb, microtrichial band; sd, spermathecal duct; sg, spermathecal gland; sp, spermatheca; v, vagina; vll, vagina lateral lobes.

Figs. 16–17. Platynus species, female left gonocoxa, ventral view. 16) P. racquelae, new species, paratype (CUIC); 17) P. luciae (CUIC). Abbreviations include: afs, apical fringe setae; ans, apical nematiform setae; des, dorsal ensiform seta; gc1, basal gonocoxite 1; gc2, apical gonocoxite 2; les, lateral ensiform setae.

Figs. 18–19. Habitats of collections of Platynus racquelae, new species (see Fig. 2a). 18) Forest at type locality, Capisterre along Crater Rim, St. John, St. Kitts Island (photo: J. Runyon); 19) Malaise trap in forest at Dos D’ane Pond, 923 m el., St. Kitts Island (photo: C. Faurot-Daniels).