Riethia queenslandensis, Cranston, 2019

Cranston, Peter S., 2019, Riethia (Kieffer 1917) (Diptera: Chironomidae) revised for the Austro-Pacific region, Zootaxa 4646 (3), pp. 461-500 : 484-486

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Riethia queenslandensis


Riethia queenslandensis sp.n.

( Figs. 2J View FIGURE 2 , 4M, 4N View FIGURE 4 , 6M View FIGURE 6 )


Riethia zeylandica (part, Cranston 1966, 2000)

Type material. Holotype. Pe/ ♂, AUSTRALIA, Queensland, Oliver Ck., 16°08.37”S 145°26.21”E, 22–23.iv.1999

(Cranston) ( ANIC). Paratypes (collected Cranston , deposited ANIC, unless otherwise stated): Queensland: Pe, P ♀, Cape Tribulation, Mason Ck., 16°05.08”S 145°27.36”E, 23.iv.1999 ; 6 Pe, Oliver Ck., 16°08.3”S 145°26.7”E (McKie), #2301; Le /P, 2 Pe , Pe / ♂, as holotype; Pe, as holotype except 10.ix.1997 (McKie) ; 5 Pe, Rex Ck., 16°28’S 145°19’E, #2283; 8 Pe , 5–6.iv.1997 GoogleMaps ; # 2281,6; 2 Pe , 10–11.vi.1997, #2282; 2L, 5 Pe , 17–18.xii.1997, #2283; 2L, 16 Pe , 17–18.xii.1997, #2282,- 4,-5; 2L, 7 Pe, Le /P, Le / Pe / ♀, P ♂, 19–20.x.1998 (Cranston & Dimitriadis) #2208 ; P ♀, Mt. Lewis, Windmill Ck., 16°34’S 145°16’E, 4.ix.2005; GoogleMaps 6 Pe , trib. Churchill Ck., 16°34’S 145°20’E, 6–7.iv.1997 GoogleMaps ; Pe , Shoteil Ck., 16°56’S 145°37’E, 9–10.ix.1997, #2302; GoogleMaps 8 Pe, nr. Mareeba , Davies Ck., 17°01’S 145°35’E, 17– 18.xii.1997 GoogleMaps ; Pe [same slide as paratype R. azeylandica ] Mt. Haig , Emerald Ck., 17°06'24"S 145°36'52"E, 17– 18.xii.1997 GoogleMaps ; 3 Pe, Herberton, Carrington Falls Ck., 800 m a.s.l., 17°20’S 145°27’E, 9–10.iv.1997 #2289; GoogleMaps L, 3 Pe , Nigger Ck., 17°26.48’S 145°29’E, 9–10.iv.1997, #2291; GoogleMaps same except 6L(P), 19–20.xii.1997, #2290; GoogleMaps 4 Pe , Palmerston N.P., Tchooratippa Ck., 17°37’S 145°45’E, 8–9.iv.1997, #2293; GoogleMaps Pe, Python Ck., 17°46’S 145°35’E (McKie), #2303; GoogleMaps 2 Pe , 2P ♂, Pixies Ck., 17°47’S 145°41’E, 2–3.ix.1997 (McKie) #2304-6; GoogleMaps 10 Pe , 2P ♂, P ♀, Cardwell, 5- mile Ck., 18°20’S 146°03’E, #2304-6; GoogleMaps Pe, Yuccabine Ck., 9.vi.1997 (McKie) GoogleMaps ; 4 Pe, Paluma , Birthday Ck., 18°59’S 146°10’E, 25–26.iii.1998 GoogleMaps ; Pe, Eungella N.P., Dalrymple Rock Rd. , 950 m a.s.l., 21°02'S 148°34'E, 22.iii.1998 GoogleMaps ; Pe, Cooloola N.P., Frankis Gulch , 26°03’S 153°04’E, 6.iv.1996, #2300. GoogleMaps

Excluded from paratype series: 2Pe, Queensland, Emmagen Ck., 16°02’S 145°27’E, 9–10.ix.1997 (McKie). Exuviae fit description but are darker especially the conjunctives and clearly lack vortex.

Other material. Queensland, L, Emerald Ck., 16°58.50’S 145°34.00’E, 8.ix. 2007, 360 m a.s.l. (Krosch) ( MV FNQDE2 R); GoogleMaps 4L, Paluma , Little Birthday Ck. / Camp Ck., 18°58’22”S 146°09’52”E, 850 m a.s.l., 21.ix.2008 (Krosch) ( MV FNQCC1 R1 , FNQCC2R1, FNQCC3R2, FNQCC3R1 (3i )); GoogleMaps 5L, Birthday Ck., 18°58.35’S 146°09.26’E, 22.ix. 2008, 800 m a.s.l. (Krosch) ( MV FNQBC5 R1 , FNQBC6R1,2,3,4); GoogleMaps L, Paluma site #1, Birthday Ck., 18°58’S 146°09’E (Krosch) ( MV PAa42); GoogleMaps 4L, Cooloola N.P., Frankis Gulch, 26°02.50’S 153°04.44’E, 18.iv.2009 (Krosch) ( MV AU09 FGR2 , 1,7,8). GoogleMaps

Description. Male (all teneral/pharate). Thorax yellow, with slightly darker vittae; legs brown, without banding. Setae of TIX thin, long, clustered, denser medially. Gonostylus narrow at junction with gonocoxite, which bears only simple setae. Superior volsella ( Fig. 2J View FIGURE 2 ), predominantly bare, except for 2 long setae disto-laterally, posterior setose projection continuous with inferior volsella, medially-directed, apically rounded digitus devoid of microtrichia, with 4–5 simple setae; inferior volsella well developed, basally appressed to inner contour of gonocoxite and linked to superior volsella, subapically with 6–7 pectinate scales and many long simple setae. Inner gonocoxite setae dispersed, linear, without tubercle ( Fig. 2J View FIGURE 2 ). Mensural features not tabulated, teneral (n=2,), B.l. c. 2.8 mm, W.l. c. 1.2–1.6 mm, AR 1.1–1.3, temp 18, clyp. 16, palp (1–4) 40–50, 115–125, 140–150, 180–190; ac 10–11, dc 8–10, Pa 3, Scts 12–17; LR1 0.95–1.0, BV1 2.14, SV1 1.8.

Female. Pigmentation as in male, AR 0.35, LR not measureable.

Pupa. Pale to brownish, with yellow-brown dorsal thorax, slightly indicated lateral apophyses on abdominal segments V–VIII; comb yellow. Frons essentially smooth with well-developed smoth to slightly tuberculose warts, contiguous from base to rounded apex. Cephalothorax with several rows of dorsal tubercles.Abdomen with continuous narrow hook row on II, c. 30–35% of segment width, and continuous conjunctival spinule bands on III and IV. Pedes spurii B distinct; vortex weak or absent. Tergites essentially as in azeylandica (q.v.) with rectangular dense armament, anterior transverse band nearly as broad as posterior armament on TII–VI; TVII with medio-posterior triangular area of spinules, TVIII posteriorly with microspinulation ( Fig. 4M View FIGURE 4 ), with few microspinules on anal lobe. Taeniate setae V–VIII 3, 4, 4, 5 on VIII evenly distributed along segment. Anterior sternites bare, with spinules on posterior of sternite VI and VII, sometimes on VIII ( Fig. 4N View FIGURE 4 ). Comb with 1 stronger posteriorly-directed spine and 2–3 weaker outer subsidiary spines, also directed posteriorly. Anal lobe with 45–55 taeniae inserted biserially.

Larva. Head capsule golden-brown with posterior postmentum and genae variably dark, with occipital margin only slightly darker, mandible golden yellow, mentum and inner 3 mandibular teeth brown. Clypeus ( Fig. 6M View FIGURE 6 ) flared anteriorly. Inner margin of mandible with serrations starting close to insertion of seta subdentalis. Premandible with small but distinct 5th (proximal) tooth. Antenna arising from distinct pedestal; AR 1.8–2.0, with 2 nd segment distinctly longer than 3 rd which is subequal to the 4 th. The ventromental plate is subequal to slightly shorter than the mentum width. Mensural features as in Table 2 View TABLE 2 .

Etymology. The species epithet reflects the restriction of this species to the state of Queensland.

Diagnosis and remarks. Adult males of R. queenslandensis conform to a ‘zeylandica’ group, as does the sometimes sympatric R. azeylandica . These two eastern Australian species may differ from one other only in subtle differences in the shape of the inferior volsella. In R. queenslandensis the inferior volsella appears to have a ridge bearing the pectinate setae subapically, on the same plane as the superior volsella ( Fig. 2J View FIGURE 2 ). In R. azeylandica the curved and broader inferior volsella has no such ridge and originates more ventral than the superior volsella ( Fig. 2A View FIGURE 2 ).

The pupa of R. queenslandensis superficially resembles others but has weakly indicated apophyses and tuberculose, rounded cephalic warts compared to the wart-less R. azeylandica (with which it can be sympatric) and R. phengari . In R. queenslandensis the spinulation on the posterior tergites is unusual. The spinulose SVI and SVII (female) and posterior third of VIII (male) in R. queenslandensis ( Figs. 4M, N View FIGURE 4 ) enhance species distinction as all sternites are bare in R. azeylandica and R. noongar .

The larvae of R. queenslandensis resemble R. azeylandica also in having a high AR of 1.8–2.2, but the 3 rd and 4 th are subequal in R. queenslandensis (4 th shorter than 3 rd in R. azeylandica ). The pigmented posterior head of R. queenslandensis may be more restricted to the prementum and less dark than in R. azeylandicus . The clypeus is more variable than figured but consistently has stronger anterolateral projections than azeylandicus ( Figs. 6L View FIGURE 6 versus 6D).

Although R. queenslandensis resembles R. azeylandica in morphology, molecular data show segregation of the two species is supported and the clusters show the morphological distinctions described above.

DIstribution and ecology. R. queenslandensis , as the name implies, is restricted to the state of Queensland, between 16° and 26°S. Sampling shows high abundance in rainforest streams from subcoastal to submontane, all in good ecological condition. Distinguished from the more widespread eastern Australian R. azeylandica by molecular and pupal morphological data allows recognition of abundance in low order but likely permanent creeks. Based on pupal exuviae, the two species co-occur in Upper Emerald Creek (17°06'24"S 145°36'52"E), mounted on same slide as, and curated under R. azeylandica .


Australian National Insect Collection


University of Montana Museum