Riethia donedwardi Cranston sp.n.

(Figs. 1A, 2C, 3F, 3K, 5F, 6F)

urn:lsid:zoobank.org:act: 503ABEA4-741D-4577-B06A-9E36B1B2789B

Riethia ‘ V4 ’, Cranston 1996; 2000.

Type material. Holotype Le/Pe/ ♂, AUSTRALIA, Western Australia, Deep River, 34°48'S 116°37'E, 13.x.1983 (Edward) (WAM), ANIC database #2187 . Paratypes (collected Cranston, deposited ANIC, unless otherwise stated): Pe, nr Walpole, Deep R., 34°55'S 116°37'E, 4.xiii.1994; Pe, Deep River, drift, 21.iii.1989 (Nolte) (ZSM) [misassociated on same slide with male of R. noongar, Zuordnung der Exuvie unsichser] ; 2L (3i) Shannon N.P., Fish Ck., 34°40'S 116°23'E, 24.xi.1995; 2Pe, Carey Bridge, Carey Brook, 34°25'S 115°47'E, 23.xi.1994, # 2189-90; L, L/P, Le/Pe/ ♂, Le/Pe/ ♀, Carey Brook, 34°25'S 115°49'E, 16–19.viii.1996 (Cranston & Judd); 4L, 2 Pe, Foster Brook, ‘ Loc S 11#2’ [32°30’S, 116°02’E], 31.iii.1983 (Bunn) (WAM) ; L, Donnelly R., Vasse Highway xing, 22–23.xi.1995, 34°20'S 115°46’, # 2189-90 ; L, Wilson's Brook, 32°32'32"S 116°02'32'E, 28.ix.2011 (Pinder) (MV WAWBV4 R8); Le/Pe/ ♂, Seldom Seen Brook, 32°15'S 116°04'E, 2.viii.1982; same except Le / Pe / ♀, 17.xi.1983 ;

Other material examined. ♂, Kimberley, 4 km W. King Cascade, CALM site 26/3, 15°38'S 125°15'E, 12– 16.vi.1988 (Weir) . Unreared larvae (including failed MV); 4L, Forth R., 34°52'S 116°23', 5.xii.1994, #2198; 5L (3i), Boxhall Ck., 27.x.2008 (Pinder); 8L, Wilson’s Brook, 32°32'32"S 116°02'32'E, 28.ix.2011 ( Pinder) ; 4L, Serpentine Dam 2, 32°21'40"S 116°01'26'E, 10.ix.2008 ( Pinder).

Description. Male. Thorax pale brown, without distinct vittae; legs with dark band covering femoral/tibial junction, tibial apex, apices of tarsomeres 1–3 and all of tarsomeres 4–5. Wing membrane unmarked. Abdomen yellow, with posterior third of all segments darkened; segment VIII and genitalia dark. Hypopygium (Fig. 1A) with TIX setae fine, long, evenly distributed; gonostylus narrower at gonocoxite junction, dilate at base, tapering to blunt point, bearing only simple setae. Superior volsella (Fig. 2C) proximally with 4 long setae at distal edge of microtrichiose region, posterior setose projection weakly developed, medially-directed subtriangular digitus anterobasally with sparse microtrichia, with 7 simple seta; inferior volsella well developed, basally appressed to inner contour of gonocoxite and linked to superior volsella, without pectinate scales, with many long simple setae. Without pseudovolsella, with distalmost seta of inner gonocoxite strong (Fig. 2C). Mensural features as in Table 1.

Female. Pigmented as male, AR 0.28, LR 1 1.1.

Pupa. Yellow-brown with darker brown dorsal thorax, anterior wing sheaths and lateral apophyses on abdomi- nal segments V–VIII; comb yellow. Cephalothorax with smooth frons without warts, thorax rugulose with tubercles on dorsum.Abdomen (Fig. 3F) with hook row on II continuous, 40% width of tergite, with strong, wide conjunctival spinule bands on III–V, close to but separated from dorsal armament of preceding segment. pedes spurii B moderately developed on II, vortex large. Tergite II with triangular armament, without anterior spinules, TIII–V with dense spinules in-filling tergite, TVI with anterior-median oval area linked narrowly to posterior transverse band; TVII and VIII with faint areas of fine spinules. Comb (Fig. 3K) with 1 stronger, triangular spine slightly curved and directed posteriorly, 2–3 weaker spines. Anal lobe with 60–65 taeniae in disorganised +/- biserial row.

Larva. Head capsule yellow with postmentum and mandible golden yellow, mentum and inner mandibular teeth golden, and strong brown-black occipital margin. Clypeus (Fig. 6F) rhomboid with clypeal setae inserted close to lateral margins. Antennal pedestal modestly developed, with small outer spine but its value in diagnosis is limited as it is not visible in many specimens. Inner margin of mandible with 3 spines near mid-point of mola. Antenna (Fig. 5F) with low AR, 3 rd segment subequal to or slightly longer than segment 2. Ventromental plate long, 1.25 width of mentum. Mensural features as in Table 2.

Etymology. The species epithet recognises the late Dr. Donald (Don) H.D. Edward, of Perth, Western Australia, who accompanied the author in the field, studied Chironomidae for 50 years, and loved and deeply understood the freshwater biota of Western Australia. The epithet should be treated as a noun in genitive case.

Diagnosis. The male of R. donedwardi is the only Western Australian Riethia with banded legs. The wing is unpigmented. In genitalic morphology the species most resembles R. cinctipes, the major difference being in the shape of the digitiform appendage of the superior volsella (Fig. 2B versus 2C). The regionally unique pigmentation applies to the female also.

The pupal exuviae of R. donedwardi is dark yellow verging on brown and has a continuous hookrow, and deep continuous conjunctival spine bands on III, IV and V. On V the conjunctival transverse band is broad, deep, and separate from the posterior spinule pattern of tergite V.

The larva of R. donedwardi has a golden mentum and inner mandibular teeth barely darker than the background golden-yellow colour. The antenna is unusual amongst all species of Riethia in having an AR close to 1 and with an antennal blade extending beyond the 5th segment.

Distribution and ecology. R. donedwardi is endemic to Western Australia with most records between 34° and 31°S with an outlier much further north, in the Kimberley. Larvae have been found in permanent creeks of low order in forested catchments.