Riethia neocaledonica Cranston 2019, sp.n.
Creators: name: Cranston, Peter S.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Chironomidae
Riethia
Riethia neocaledonica

description: Riethia neocaledonica sp.n.
(Figs 2F, 4K,L, 5G, 6H)
urn:lsid:zoobank.org:act
Type material. Holotype ♂, slide mount, Euparal, NEW CALEDONIA, S. Prov., Mt. Mou, road xing, 22°04’S 166°20’E, c 200 m a.s.l., 26.i.2003 (P.S. Cranston). Paratypes (collected Cranston, deposited ANIC, unless otherwise stated, all slide mounted) 1 Pe / ♀, 13 Pe, 3 L(P), 6L, as holotype; 4 Pe, N. Prov., N. La Foa, 20°29’S 165°48’E, 1.ii.2003; Mt. Panié, refuge, 500 m a.s.l., 5.xii.1990 '#90.285' (M. Baylac) (MNHN); ♂, ‘For Inf Mt Mou / 200 250 m., M B Ruiss / Muséum Paris / Nouvelle Calédonie / Exped L. & D. Matille, nov. dec. 1983 ’ 16.ix.1983 (L. & D. Matile) (MNHN); 4 Pe, L, Mt. Khogis, cascades, 22°09’S 166°32’ E, c. 500 m a.s.l., 28.i.2003; 10 ♂, 6 ♀, c. 300 m. S. Koghis restaurant, 22°10’58”S 166°30’6”E, 417 m a.s.l., 16–26.xi.2003 (Johanson via Espeland), includes MV NCALR3.
Description. Male. Thorax yellow with dark vittae, scutellum and especially postnotum. Legs banded, with distal apices / subapices of femora, tibiae and much of each tarsomere darker brown on yellow. Wing faintly brown including around yellowish veins, but without bands. Tergites yellow with brown transverse bands on posterior of TII—V, VI pale, VII, VIII and hypopygium darkened. Tergite IX medially with cluster of 10–12 broad strong setae, 1.5– 2x usual width of TIX setae. Gonostylus merges evenly into gonocoxite which tapers gradually to terminal small hook, with only simple setae. Digitus of superior volsella narrow at base then more dilate bearing 7–9 small simple setae (Fig. 2F). Pseudovolsella angular projection with 3 long setae (Fig. 2F). Inferior volsella bare at base, apically with 5–6 short apically pectinate setae and 3 longer flattened scales. Mensural features as in Table 1.
Female. Pigmented as male, AR 0.3, LR 1 1.0.
Pupa. Darkened with brown thorax including veins and margins of wing sheath and all apophyses. Frons with small warts. Thorax densely and broadly rugulose with several rows of dorsal tubercles. Abdomen with continuous hook row 50% of tergite width, and broad conjunctival spinule bands on III, IV and on V, thinner, narrower band of spinules, well separated from posterior tergal spinules (Fig. 4L). Pedes spurii B very weak. vortex well developed. Tergal spinule pattern closely resembling that of R. stictoptera (Fig. 4D) notably in lack of anterior spinules on TII, differentiated anterior and posterior stronger spinules on TII–VI (Fig. 4L), and in the spinulation of TVII, VIII and anal lobe. Taeniate setae V–VIII 3, 4, 4, 5; L 3–5 on VIII somewhat clustered, with respect to L 1–2. Comb (Fig. 4K) with one strong tooth, 3-much smaller inner teeth. Anal lobe fringe dense with 35–40 uni- biserially inserted taeniae.
Larva. Head capsule evenly golden-yellow with broad and dark postoccipital margin; mentum and inner mandibular teeth distinctly golden brown with apical mandibular tooth golden, long and curved. Clypeus (Fig. 6H) c. 2× as wide as long (70 × 32 µm), with strongly indented lateral margins and S3 setal bases aligned with innermost point of the lateral contour, close to lateral margin (Fig. 6H). Dorsal sclerite broadly flared anterior to S2 setae. Antenna (Fig. 5G) ratio low at 1.1–1.2; 2 nd segment shorter than 3 rd; walls of segment 3 notably thinner than others; segment 4 at least 80% length of segment 2. The ventormental plate is very similar to slightly shorter than the width of the mentum. Mensural features as in Table 2.
Etymology. From adjectival caledonica from caledonia, the roman name for current day Scotland, probably from celtic. The ‘neo’ refers to James Cook’s (fanciful) belief in the resemblance of the island of New Caledonia to Scotland.
Diagnosis. The species is endemic to New Caledonia. The male with banded legs, ‘conventional’ shaped gonostylus, digitus of superior volsella narrow at base then more dilate, and inferior volsella with pectinate setae is distinctive. In the pupa, the narrow transverse and medially interrupted band of spinules on conjunctive V, well separated from posterior tergal spinules (Fig. 4L), is unlike any other species. Generally the pupa resembles that of R. stictoptera (Fig. 4D) but the intensity of pigment and the interrupted conjunctival band on V distinguishes. The larva is distinguishable by antennal features (ratios) and the clypeus shape.
Remarks. The life history association comes from L(P) and P(♀) and being the sole species in New Caledonia.
Distribution and Ecology. Riethia neocaledonica is endemic to the island of New Caledonia where it occurs in low order streams, although apparently not in lateritic areas.
description: Published as part of Cranston, Peter S., 2019, Riethia (Kieffer 1917) (Diptera: Chironomidae) revised for the Austro-Pacific region, pp. 461-500 in Zootaxa 4646 (3) on pages 479-480, DOI: 10.11646/zootaxa.4646.3.3, http://zenodo.org/record/3351058