Mecyclothorax palustroides, Liebherr, James K., 2015

Liebherr, James K., 2015, The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation, ZooKeys 544, pp. 1-407 : 279-282

Taxon classification Animalia Coleoptera Carabidae

(111) Mecyclothorax palustroides sp. n. Figs 145E, 146E, 149B, 151, 152

Diagnosis.

This species can be diagnosed by the impressed elytral striae 1-3 that are irregular along their length but not distinctly punctate, and the broadly flavous elytral apical, lateral, and sutural margins (Fig. 149B). The elytral coloration varies infraspecifically. The lateral intervals 7-9 are flavous in contrast to the rufopiceous discal intervals 2-6 in some individuals. Alternatively, the elytra may exhibit gradually paler lateral margins, with intervals 7 or 7-8 rufobrunneous mesad the more flavous 9th interval and lateral marginal depression. The breadths of the flavous apical and lateral marginal bands are positively associated, with the apex variably pale from beyond the posterior seta of the lateral elytral setal series, or more narrowly pale beyond the apical fusion of striae 3 + 4 (Fig. 149B). Individuals with differing degrees of pale margination coöccur within the same collecting series. Individuals of this species are most similar to those of Mecyclothorax tauberorum and Mecyclothorax pau , though both of those species are characterized by darker, less contrasted lateral elytral margins. Individuals of Mecyclothorax palustroides are all larger than those of Mecyclothorax tauberorum ; standardized body length for this species = 4.6-5.5 mm versus s.b.l. = 3.9-4.6 mm for Mecyclothorax tauberorum . Mecyclothorax palustroides can be diagnosed from Mecyclothorax pau by the more upraised sculpticells in the transverse discal elytral microsculpture, imparting an alutaceous sheen to the surface, and by the more broadly paler elytral intervals 8-9 posterad the humerus; that pale margin either rufobrunneous or flavous versus the rufopiceous disc. Also, the male aedeagal median lobe can definitively diagnose the 3 species: 1, Mecyclothorax palustroides with the lobe apex broadly rounded (Fig. 152); 2, Mecyclothorax tauberorum with the lobe apex short and bluntly rounded (Fig. 161A, C–D); and 3, Mecyclothorax pau with the lobe apex elongate, narrowly rounded (Fig. 161 E–F, H–L). Setal formula 2 1 2 0.

Description

(n = 5). Head capsule with frontal grooves broad near clypeus, triangularly expanded medially, and divergent to terminate mesad fine carina inside anterior supraorbital seta; dorsal impression of neck slightly concave; ocular lobe obtusely protruded from gena, ocular ratio = 1.50-1.58, ocular lobe ratio = 0.81-0.84; labral anterior margin angularly emarginate to 1/9 labral length; antennae filiform, antennomeres 2-3 with sparse pelage of short setae; mentum tooth with sides acute, apex tightly rounded. Pronotum slightly transverse, MPW/PL = 1.08-1.21, variably constricted basally, MPW/BPW = 1.52-1.68; lateral margins convergent for short distance anterad right hind angles, the basal margin convex just mesad hind angle; median base distinctly depressed relative to disc, elongate punctures bordering disc, ~19 isolated punctures each side; basal margin trisinuate, slightly convex medially; median longitudinal impression very shallow, middle of disc flat; anterior transverse impression obsolete medially, finely incised laterally, fine longitudinal wrinkles extended from impression across flat anterior callosity; front angles slightly projected, tightly rounded; pronotal apical width variably broader than pronotal basal width, APW/BPW = 1.02-1.18; lateral marginal depression narrow, edge upturned laterally, slightly broader at front angle; laterobasal depression narrow, surface irregular, continuous with lateral depression. Proepisternum with 5 minute punctures along hind marginal groove; prosternal process with narrow median impression, lateral margins broadly upraised. Elytra subovoid, lateral margins rounded posterad humeral angles, disc convex, sides distinctly sloped to marginal depression; basal groove evenly curved to subangulate humerus, MEW/HuW = 2.21-2.33; parascutellar seta present; parascutellar striole with 4-5 punctures, striole very shallow between punctures; sutural interval coplanar with lateral intervals basally, upraised in apical half; sutural and 2nd striae of similar depth on disc, sutural interval continued as isolated punctures at base, sutural stria deep, smooth and finely incised apically, 2nd stria broader and irregularly interrupted apically; discal striae 2-5 progressively shallower, inner striae irregular, lateral striae represented by isolated punctures, striae 6-7 traceable only as series of very shallow punctures at midlength; mesal intervals slightly convex, lateral intervals flat; apex with striae 1, 2, 7, and 8 present, striae 3-6 obsolete, though intermittently traceable; 8th interval slightly convex laterad 7th stria mesad subapical sinuation; 2 dorsal elytral setae at 0.27 × and 0.54 –0.64× elytral length, setal impressions small, shallow, spanning ½ width of interval 3; lateral elytral setae arranged in anterior series of 7 setae and posterior series of 6 setae; elytral marginal depression moderately broad with edge upturned laterad humerus, narrowed to a beaded margin at subapical sinuation; subapical sinuation shallow, more abruptly incurved anteriorly. Mesepisternum with ~9-10 punctures in 2-3 rows; metepisternal width to length ratio = 0.71; metepisternum/metepimeron suture distinct. Abdomen with irregular lateral wrinkles on ventrites 1-5, lateral depressions on ventrites 3-6; suture between ventrites 2 and 3 complete; apical male ventrite with 2 marginal setae and apical female ventrite with 4 equally spaced setae and median trapezoid of 4 subequal, short setae. Legs-metatarsomere 1/metatibial length ratio = 0.20; metatarsomere 4 length along outer lobe 1.3 × medial tarsomere length, apical and subapical setae present; metatarsal dorsolateral sulci broad, shallow, basal tarsomere medially subcarinate. Microsculpture of vertex a distinct transverse mesh, sculpticell breadth 2 –3× length; pronotal disc with shallow transverse mesh, sculpticell breadth 3 –4× length, median base with indistinct transverse mesh, sculpticell breadth 2 × length; elytral apex with shallow isodiametric and transverse sculpticells, sculpticell breadth 2 × length; metasternum with shallow transverse mesh; laterobasal abdominal ventrites with swirling isodiametric and transverse microsculpture. Coloration of vertex rufobrunneous with piceous cast; antennomeres 1-3 rufoflavous, 4-11 rufobrunneous; pronotal disc rufobrunneous with piceous cast, lateral margins narrowly, and base and apex rufoflavous; proepipleuron rufoflavous, proepisternum dorsally rufoflavous, ventrally rufobrunneous; elytral disc dark rufobrunneous with iridescent sheen, sutural interval rufous in basal half, rufoflavous in apical half; elytral epipleuron rufoflavous, metepisternum rufobrunneous; abdomen with ventrites 1-3 rufopiceous medially, rufoflavous laterally, ventrites 4-6 basally rufobrunneous, apically flavous, the apical ventrite flavous in apical 3/4; metafemur flavous; metatibia flavous with rufoflavous cast.

Male genitalia (n = 19). Aedeagal median lobe gracile to slightly robust, dorsal and ventral margins subparallel along median shaft, distance from parameral articulation to tip 3.2 –4.1× depth at midlength (Fig. 152A, C–H); apex broadly and briefly extended, tip slightly curved apically along ventral margin, slightly expanded along dorsal margin, with obliquely convex apical face; median lobe broadly, evenly curved rightward apically in ventral view (Fig. 152B, F), the concave right margin and convex left margin convergent to blunt, oblique tip; internal sac with very pale, diffuse dorsal ostial microtrichial patch near base, and variably ornamented ventral surface, covered either with shaggy pelage of microspicules (Fig. 152G), or a ventral ostial microtrichial patch composed of overlapping scaly macrospicules (Fig. 152H); flagellar plate moderately sized, length 0.40 × parameral articulation-tip distance.

Female reproductive tract (n = 1). Bursa copulatrix columnar with basally constricted apical lobe, length 1.08 mm, apical cap 0.40 mm long × 0.29 mm broad, width at midlength 0.40 mm (Fig. 145E); bursal walls translucent, thickly wrinkled; gonocoxite 1 with 4 apical fringe setae, a curved seta near medioapical angle and 3-5 smaller setae on medial surface (Fig. 146E); gonocoxite 2 falcate, apex broad with sensilla doubled along lateral margin, base broadly extended laterally, 2 lateral ensiform setae, apical nematiform setae on medioventral surface at 0.77 × gonocoxite length.

Holotype.

Male (CUIC) labeled: HI: Maui Haleakala NW / slope Waikamoi Pres. / trans. 3 @ 1700 m el. / 10-IV-1991 sifting / litter J.K. Liebherr // HOLOTYPE / Mecyclothorax / palustroides / Liebherr / det. J.K. Liebherr 2015 (black-margined red label).

Paratypes.

61 specimens (see Appendix).

Etymology.

This species’ resemblance to Mecyclothorax palustris (Sharp) leads to the use of palustroides as the species epithet. The stem palustris describes marshy or swampy situations.

Distribution and habitat.

Mecyclothorax palustroides is known from the Waikamoi area, Ke‘anae Valley, and upper Kīpahulu Valley at 1265-2045 m elevation (Fig. 151). Its distribution is congruently disjunct across the Hanawī face of Haleakalā with several other widespread species in the Mecyclothorax palustris group; i.e. Mecyclothorax nanunctus (Fig. 157), Mecyclothorax unctus (Fig. 160), and Mecyclothorax pau (Fig. 163). The Kopili‘ula drainage at the center of this gap has experienced significant dieback of the ‘Ōhi‘a Forest ( Holt 1983), with the area now characterized by open koa “savannah” standing in dense tangles of Dicranopteris (uluhe) fern. However this particular area of ‘ōhi‘a loss represents only a portion of the range disjunctions for the various species, likely requiring a more complicated solution to the explanation of this biogeographic pattern.