Rentonium bicolor Gimmel &amp; Leschen 2013, sp. nov.
Creators: name: Gimmel, Matthew L.
name: Leschen, Richard A. B.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Trogossitidae
Rentonium
Rentonium bicolor

description: <i>Rentonium bicolor</i> sp. nov. (Figures 1–7) <i>Diagnosis</i> Adults may be distinguished from the other two described species of <i>Rentonium</i> by the shorter clypeus and undulate dorsal setal pattern. Additionally, it may be separated from <i>Rentonium daldiniae</i> Crowson by the colouration (elytron dark brown with at least three nebulous yellow spots in <i>R. daldiniae</i>, light reddish-brown with infuscated lateral margins in <i>R. bicolor</i>), and by the pronotal vestiture (directed more or less posteriorly in <i>R. daldiniae</i>, radiating outward from a medial point in <i>R. bicolor</i>). It may also be separated from <i>Rentonium chilense</i> by the colouration (unicoloured dark brown in <i>R. chilense</i>). <i>Rentonium bicolor</i> keys to the genus <i>Australiodes</i> Endrödy-Younga in Crowson (1966) based on the partly fused maxillae, but also to <i>Rentonium</i> based on the short vestiture. It also partly keys to <i>Rentonellum</i> Crowson in Crowson (1970) based on aptery, though <i>R. bicolor</i> is brachypterous and not entirely glabrous. <i>Rentonellum</i> is a very diverse genus with many undescribed species in New Zealand. Though many species are dorsally glabrous, some have weak vestiture, but not as obvious as that in <i>R. bicolor</i>. <i>Rentonium bicolor</i>, <i>Australiodes vestitus</i> (Endrödy-Younga) and many <i>Rentonellum</i> also have well-developed punctures in a transverse row on the abdominal ventrites. The abdominal punctures are smaller in <i>R. bicolor</i> than in <i>A. vestitus</i>. <i>Rentonium bicolor</i> also differs from the described species and one similar-looking undescribed species from New Caledonia by the lack of dorsal spots, absence of long erect to suberect setae, and the lack of fully developed hind wings. <i>Rentonium bicolor</i> larvae can be distinguished from the undetermined larva described by Crowson (1966) by having a more grub-like body, a single hooked urogomphus, four stemmata, and the apical seta of the antenna subequal in length to the antenna. <i>Adult description</i> Length 0.9–1.1 mm (measured mid-dorsally from anterior edge of pronotum to tip of elytra). Body form (Figure 1A–C) highly globose, no more than 1.3 times longer than wide when viewed dorsally (head excluded); evenly arcuate laterally, without constriction between pronotum and elytra; colour predominantly pale reddish-brown, with legs and palpi slightly paler; antennal club, temples and about lateral onequarter of elytron infuscated, sometimes with pronotum medially and sub-laterally, and elytron near scutellum infuscated. Head capsule widest at eyes, without temples or postocular constriction (Figure 2A); epistomal region relatively short, clypeus hardly projecting anteriorly, truncate at apex (Figure 2A); frons punctate, each puncture bearing a recumbent, anteriorly directed seta; punctation fine, punctures separated by slightly more than their diameters medially on frons, becoming more dense laterally, where separated by less than their diameters. Eyes prominent, separated by about 3.9 times their diameter when viewed dorsally (Figure 2A). Labrum (Figure 2B) about twice as wide as long, truncate to slightly emarginate, with scattered long setae dorsally; tormal processes Y-shaped. Antenna (Figure 2C) 11-segmented, scape about twice as wide as pedicel; antennomere VIII slightly asymmetrical, wider than VII; antennomeres IX–XI abruptly widened, forming compact club; antennomere XI slightly wider than long, with smoothly rounded apex. Mandible (Figure 2D) bidentate at apex, with three blunt retinacular teeth; prostheca not prominent, with a few inconspicuous setae. Maxilla (Figure 2E) bearing a short apically articulated galea and lacinia fused with stipes, together nearly as long as palp; galea with dense brush of long setae; lacinia with uncus and with a few setae at apex; maxillary palp four-segmented; palpomeres II and III similar in size and shape, about as wide as long; palpomere IV narrower than III, conical, rounded at apex. Labium (Figure 2F) with mentum transverse, broadly emarginate, with transverse row of pores near base; ligula truncate, with scattered long and short setae; labial palps three-segmented, palpomere III parallelsided, much narrower and slightly shorter than palpomere II. Gena with short but distinct antennal groove, not extending posteriorly beyond posterior margin of eye; gular sutures widely separated, more or less parallel, disappearing anteriorly. Pronotum evenly convex, anterior emargination deep (Figure 3A); punctation very fine to nearly absent on central part of disc, posteriorly and laterally becoming about as coarse as that of head, but nowhere as dense; vestiture of recumbent setae radiating outward from a point about one-third distance from anteromedial margin of pronotum. Prosternum without disc, with only a short, even, keel-like elevation between procoxal cavities. Scutellar shield broader than long, triangular, narrowly rounded at apex. Elytron about 1.4 times longer than wide, punctation fine and confused with dorsal setae forming undulating pattern; widened portion of epipleuron short, gradually tapered posteriorly, disappeared about one-third to one-half distance from humerus, at no point wider than metepisternum. Mesoventrite (Figure 3D) with anterior portion deeply sunken dorsally, without distinct procoxal rests, posterior portion forming a narrow, flat, triangular tablet between the nearly contiguous mesocoxal cavities. Hind wing greatly reduced, strap-like, length less than width of pronotum. Metaventrite (Figure 3D) densely, uniformly punctate, punctures separated by about their diameters or less; discrimen absent; metanepisternum longtriangular, gradually narrowing anteriorly to posteriorly. Metendosternite (Figure 3C) with moderately wide base and long, slender lateral arms; laminae moderately developed, widely separated. Metacoxae separated by about width of metatibia. Protibia (Figure 3B) slighly more expanded than mesotibia and metatibia, with about 15 wide, flat serrations on outer edge; metafemur distinctly shorter than profemur and mesofemur; tibial spur formula 2-2-2, inner (ventral) spur shorter than outer; tarsal formula 5-5-5, tarsomeres each about as long as wide, except tarsomere V which is about twice as long as wide. Abdominal ventrites densely punctate, punctures on ventrite I especially coarse (coarser than those of metaventrite) and with a single transverse row of large punctures on ventrites II–V (largeston III–V); ventrites lacking rows of stout setae; ventrite I measured behind coxa about as long as ventrites II and III combined (Figure 3E). Aedeagus with penis (Figure 4A) long and slender, tapered gradually from base to apex, with narrowly rounded apex and two rounded, dorsoventrally flattened basal struts; tegmen as in Figure 4B. <i>Late-instar larval description</i> Length early instar (0.55–0.75 mm, <i>n</i> = 2); late instar 0.7–1.5 mm, mean = 1.2 mm, <i>n</i> = 16). Body (Figure 5A–C) stout and grub-like, head hypognathous. Head capsule about 1.3–1.4 times wider than long (measured dorsally, including clypeus); frontoclypeal suture present; median endocarina long, extending to about level of frontoclypeal suture; frontal arms widely separated at base, not joined with endocarina, represented by broad depigmented regions in head capsule, sclerotized hind margin of head capsule broadly interrupted at intersections with frontal arms (Figures 5A, 6A); hypostomal rods heavily sclerotized (Figures 5C, 6B), complete to posterior margin of head capsule; dorsal chaetotaxy as in Figure 6A, ventral chaetotaxy as in Figure 6B, clypeus devoid of setae. Antenna (Figure 6A) two-segmented; antennomere I about 0.2 times as long as broad, antennomere II 2.5–3.0 times as long as broad; sensorium arising from antennomere I, ventral to antennomere II, similar in shape and size to antennomere II; antennomere II with terminal seta about as long as antennomere II. Stemmata four (Figure 6C), three in a vertical row just posterior to antennal insertion, with a smaller “ventral pigment spot” just ventral to this row, a fourth stemma more distal. Labrum (Figure 6A) broad, slightly emarginate, with close-set row of four stout, medially curved setae on each side occupying lateral quarter of labrum; a pair of longer setae present, arising just medial and proximal to the close-set rows. Mandible (Figure 6D) stout, bifid at apex; dorsal cutting edge with three sharp subapical teeth (blunt in older late instar larvae and prepupae, Figure 6E), a sharp subapical retinaculum present, which is more acute and tapered on the right mandible. Ventral mouthparts retracted. Maxilla (Figure 6F) with palp two-segmented, segment I slightly transverse with a well-developed apical sensorium, segment II about twice as long as wide with cluster of short peg-like setae at apex; mala with uncus consisting of a single spine, four elongate spine-like setae on the mesal surface, three stout setae and three fine setae subapically; maxillary articulating area absent; cardo fused to stipes. Labium (Figure 6B) with palp one-segmented, about twice as long as wide, palps separated by about their individual length; terminal palpomere with cluster of peg-like setae at apex; ligula broadly rounded, devoid of setae; mentum posterior to palps about as long as wide, devoid of setae; submentum long, tapering anteriorly, with pair of setae. Thoracic segments devoid of sclerotized areas (Figure 5A), tergite I reduced dorsally; legs (Figures 5B, 6G) short, coxae widely separated; tarsungulus devoid of setae. Abdominal segments about equal in size to thoracic segments II–III; abdominal segments I–VIII devoid of sclerotized areas (Figure 5A), approximately equal in width except segment VIII narrower. Abdominal spiracles annular-biforous, lacking accessory chambers. Abdominal segment IX roughly conical, tergite IX (Figure 6H,I) sclerotized, nearly vertical (facing posteriorly) and bearing a single, median, strongly upturned and well-sclerotized urogomphus; urogomphus about 0.5 times as long as sclerotized plate of tergite IX, with paired short lateral spines about half distance to apex; tergite IX plate with six pairs of long setae and two pairs of short setae, and a pair of short spines just lateral to base of urogomphus; with pair of small tubular openings located posterior to anteromedial pair of setae. <i>Type material</i> <i>Holotype</i>. “NEW ZEALAND: WO:\ Whareorino Forest, Mangatoa Tk.\ 38°24.985 <i>ʹ</i> S 174°43.312 <i>ʹ</i> E \ex yellow Hypocrea stromata\ 04Mar2012 coll. M.L. Gimmel \ R.A.B. Leschen RL1668” (NZAC). <i>Paratypes</i> (71 adults, 33 larvae; all material adults except where specified). <b>NEW ZEALAND: AK:</b> North Auckland, Waiwera, litter, 07 December 1961, G. Kuschel, 61/11 (2, NZAC); Lynfield, Wattle Bay, ex pile of dead tree fern fronds in bush at night, 25 August 2002, S.E. Thorpe (1, AMNZ); Mataitai Forest S.A., pitfall, January 2002, A. Warren (1, AMNZ); same except March 2002 (1, AMNZ); Atuanui, Mount Auckland, pitfall, January 2002, A. Warren (1, AMNZ); <b>BP:</b> Waenga Bush, Lottin Point Road, pit traps, 20 October–24 November 1992, G. Hall (1, NZAC); <b>CL:</b> Tapu Road Summit, decayed wood, 25 March 1977, G. Kuschel (1, NZAC); Coroglen-Tapu Summit, 36°59′S, 175°35′ E, litter, 03 November 2005, R. Leschen, S. Nomura, RL985 (1, NZAC); Kauaeranga National Park, Kauaeranga Kauri Track, 37°04.170 <i>ʹ</i> S, 175°39.952 <i>ʹ</i> E, 154 m, ex sifted leaf litter and wood, 15 January 2009, K. Marske, R. Leschen, K. Puliafico, T. Thery, KM303 (2, NZAC); Little Barrier Island, Te Waikohare Stream, flood debris, 28 November 2006, R. Leschen, T. Buckley, K. Marske, D. Seldon, RL1136(22) (8, NZAC); Great Barrier Island, pitfall, March 2002, A. Warren (1, AMNZ); same except April 2002 (1, AMNZ); Great Barrier Island, Mount Hobson, leaf litter, 17 December 2003, R. Leschen, RL805 (1, AMNZ); <b>GB:</b> Te Urewera National Park, Maori Track, 38°44′ S, 177°09′ E, ex <i>Trametes versicolor</i>, 17 November 2004, R. Leschen, RL879 (1, NZAC); <b>ND:</b> Waipoua Forest, SH12, rotten stumps/trees, 20 September 1977, D.W. Helmore, 77/102 (1, NZAC); same except mosses and liverworts, L.L. Deitz, 77/103 (1, NZAC); Waipoua Forest, sifted litter, 25 November 1980, G. Kuschel, 80/121 (1, NZAC); Waipoua Forest, Yakas Track, 35°37′ S, 173°32′ E, flight intercept trap, 29 March–5 May 1999, R. Leschen, R. Hoare, FIT A 409 (1, NZAC); Waipoua Forest, Yakas Track, 35.61717 S, 173.52986 E, sifting leaf litter and rotten wood, 5 April 2010, C. Carlton, R. Leschen, RL1502 (1, NZAC); Waipoua State Forest, Waipoua Summit, 387 m, berlese from leaf litter in podocarp-mixed broadleaf forest, 11–14 April 1980, A. Newton, M. Thayer (1, ANIC); Waipoua Forest, Tanemahuta, sifted litter, 29 October 1985, R.C. Craw, C. Lyal, 85/48 (1, NZAC); Waipoua Forest, SH 12, rotten stumps and trees, 20 September 1977, D.W. Helmore, 77/102 (1, NZAC); Waima Forest, Wekaweka Track, 35°34′ S, 173°36′ E, leaf litter, 13 June 2000, R. Leschen, G. Hall, RL583 (1, NZAC); Omahuta Forest, Kauri Sanctuary, litter, 16 July 1974, G. Kuschel, 74/40 (1, NZAC); Opua Forest, Paihia, litter, 23 January 1981, G. Kuschel (1, NZAC); Waitangi Forest, litter and decayed wood, 2 November 1981, G. Kuschel, 81/116 (3, NZAC); same except 81/117 (1, NZAC); Mount Manaia, 150–300 m, litter and decayed wood, G. Kuschel (1, NZAC); Parahaki Park, litter and decayed wood, 5 November 1981, G. Kuschel, 81/127 (5, NZAC); Te Paki Trig, sifted litter and decayed wood, 23 November 1982, G. Kuschel, 82/116 (2, NZAC); Radar Bush, Te Paki, 34°28.382′ S, 172°45.947′ E, sifting leaf litter/dead wood, 4 November 2008, R. Leschen, T. Buckley, RL1357 (3, NZAC); Puketi Forest Headquarters, 35°13′ S, 173° 47′ E, sifted leaf litter, 31 March 1999, R. Leschen, R. Hoare, RL376 (1, NZAC); Tangihua Ranges, near lodge, 35°54′ S, 174°08′ E, leaf litter, moss, rotting log, 13 February 2000, R. Leschen, G. Hall, R. Hoare, RL530 (1, NZAC); Kaiwhetu, north of Hihi, “Krause Property,” 34°57 <i>ʹ</i> S, 173°32 <i>ʹ</i> E, leaf litter, 15 February 2000, R. Leschen, G. Hall, R. Hoare, RL533 (2, NZAC); Mangamuka Gorge S.R., 6.6 km northwest of Mangamuka, 35°12′ S, 173°29′ E, 70 m, hardwood-podocarp forest, 25 November 1984, A. Newton, M. Thayer, #682 (3, FMNH); Mangamuka Track, 35°11 <i>ʹ</i> S, 173°28 <i>ʹ</i> E, FIT, 28 July–1 August 1998, R. Leschen, R. Hoare (1, NZAC); same except 30 March–5 May 1999, R. Leschen, R. Hoare, G. Hall, RL366 (3, SEMC); same except 12 June 1999, R. Leschen, E. Hilario, RL422 (1, NZAC); Trounson Kauri Park, 35°44 <i>ʹ</i> S, 173°39 <i>ʹ</i> E, under rotten branches, 27 January 1998, R. Leschen, A. Davelos, 166 (1, NZAC); <b>TO:</b> Hauhungaroa Range, east side, 2250′, litter, 20 November 1965, J.I. Townsend, 65/610 (1, NZAC); Mount Pureora, 1160 m, sifted litter, 14 October 1982, G. Kuschel, 82/93 (1, NZAC); <b>WO:</b> same data as holotype (10, NZAC). <i>Questionable record (excluded from type series):</i> <b>MC:</b> Banks Peninsula, Peraki Saddle Scenic Reserve, 500 m, log and leaf litter, hardwood podocarp elfin forest, 11 December 1984, A. Newton, M. Thayer, #701 (2, FMNH). <b>Note:</b> This record may be the result of mislabelling, as these are the only South Island specimens so far known. <i>Larval material</i> <b>NEW ZEALAND: WO:</b> same data as holotype (30 late-instar [5 slide-mounted], four early instar, NZAC). <i>Distribution</i> This species is known only from Northland south to central North Island (Figure 7B). <i>Etymology</i> The epithet <i>bicolor</i> refers to the (usually) distinctly two-toned habitus of the adult. This epithet is a noun in the nominative singular, standing in apposition.
description: Published as part of <i>Gimmel, Matthew L. &amp; Leschen, Richard A. B., 2013, A new species of mycophagous Rentonium (Coleoptera: Cleroidea: Trogossitidae) based on larvae and adults, and a catalogue of Rentoniinae, pp. 863-880 in Journal of Natural History (J. Nat. Hist.) (J. Nat. Hist.) 48 (15 - 16)</i> on pages 864-874, DOI: 10.1080/00222933.2013.839846, http://zenodo.org/record/5199048
description: {"references": ["Crowson RA. 1966. Further observations on Peltidae (Coleoptera: Cleroidea), with definitions of a new subfamily and of four new genera. Proc R Entomol Soc Lond Ser B. 35: 119 - 127.", "Crowson RA. 1970. Further observations on Cleroidea (Coleoptera). Proc R Entomol Soc Lond Ser B. 39: 1 - 20."]}