Cricotopus albitarsis Hergstrom

Drayson, Nick, Cranston, Peter S. & Krosch, Matt N., 2015, Taxonomic review of the chironomid genus Cricotopus v. d. Wulp (Diptera: Chironomidae) from Australia: keys to males, females, pupae and larvae, description of ten new species and comments on Paratrichocladius Santos Abreu, Zootaxa 3919 (1), pp. 1-40 : 6-8

Cricotopus albitarsis Hergstrom sp. n.

( Figs. 1 B, 2B, 4B, 6A, 7C, 8B, 10B)

urn:lsid:zoobank.org: act :84145205-2AFE-4C9C-B479-152EDEBA9336

Cricotopus albitibia (Walker, 1848: 16) sensu Freeman, 1961: 647 [misidentified]. Cricotopus albitarsis Hergstrom 1974: 94 [Invalid ICZN, 1985: Article 8a]. Cricotopus ‘sp. I’ Drayson, 1992: 49

Cricotopus “ albitarsis ” sp. nov. Drayson & Cranston, in Cranston, 1996: 86 [Invalid; author states ‘not formal publication for nomenclatural purposes]

Type material. Holotype: ♂, AUSTRALIA, SA, Adelaide, Torrens Lake, 10.ii.1970 (Hergstrom)( ANIC). Paratypes ♂, ♀, as Holotype.

Other material examined. Qld: P♂, Mt Elliot NP, Alligator Ck., 23.iii.1998 (Cranston); 11 Pe, Carnarvon NP, Carnarvon Ck., 25°04'S 148°14'E., 4/ 5.vi.1991 (Black); Pe, Conondale Range, Stony Ck. #2, 26°52'S 152°44'E, 24.v.1990 (Cranston); 10 Pe, L, Atkinson Dam, 27°06'S 152°02'E, 24/ 25.vii.1991 (Cook, Cranston & Hillman); Le/Pe/♂, 3Pe/♀, Pe, L, Brisbane R., Mt. Crosby, 27°32'S 152°47'E, 19.i.1990 (Cranston); Le/Pe/♀, Brisbane R., Mt. Stanley, 270° 32'S 153°29'E, 19.i.1990 (Cranston).

NSW: 1♀, 1 Pe, Gaya-Dari, Upper Clarence R., 28°44'S 152°04'E, 20.i.1991 (Cranston); 12 Le/Pe/♂, Ginninderra Falls, 35°13'S 148°58'E, 6.xii.1987 (Cranston); Le/Pe/♂, Kosciuszko NP, Yarrangobilly R., Yarrangobilly Caves, 35°44'S 148°29'E, 15.i.1992 (Cranston); 5 Pe, Albury-Wodonga, Murray R., Noreuil Park, 36°05'S 146°56'E, 22.xii.1989 (Cook); 8 Pe, Albury-Wodonga, Causeway, Murray R., 36°06'S 146°55'E, 26.ii.1990 (Cook); Le/Pe/♂, 14 Pe, Albury-Wodonga, Murray R. Stn 6, 36°06'S 147°01'E, 17.v.1989 (Cook); Pe, Albury-Wodonga, Murray R., Waterworks, 36°07'S 146°04'E, 21.xi.1989 (Cook); ♀, Jindabyne, Rush's Ck., 36°24'S 148°40'E, 12.xii.1987 (Cranston).

ACT : 2 Pe, Canberra, Lake Burley Griffin, Black Mt. Peninsula, 35°16'S 149°07'E, 18.i.1992 (Rosewarne); 7 Pe, Tuggeranong, Isabella Pond, West shore, 35°25'S 149°06'E, 29.xii.1991 (Rosewarne); 5 Pe, Tuggeranong, Isabella Pond, East shore, 35°25'S 149°06'E, 29.xii,1991 (Rosewarne); 5 Pe/♂, 5 Pe, 2 L, Molonglo R., Coppins Crossing, 35°17'S 149°02'E, 4, ii.1988 (Cranston); same except ♂, 7.xi.1987; same except 3 Le/Pe/♂, 3 Le/Pe/♀ Pe, 25.ii.1991 (Drayson).

Vic: 3♀, 41 Pe; House Ck. down-stream, 36°09'S 146°52'E, 19.xii.1989 (Cook); 7 Pe, Albury-Wodonga, Middle Ck., downstream White's Rd, 36°09'S 146°57'E, 20.iii,1990 (Cook).

WA: 2 ♂, 4♀, 2 Le/Pe/♀, 20 Pe, 2 L, Walpole-Nornalup NP, Frankland R., circular pool, 34°56'S 116°47'E, 21.xi.1990 (Cranston); ♂, Lake Monger, 3.iii.1955 (Hodgkin); 2♂, ♀, 5 L, Lesmurdie Falls, 1.xii.1978 (Edward).

NT; ♂, Kakadu NP, near Jabiru, Gulungul Ck., 12°39'S 132°53'E, 11.iv.1989 (Cranston); 3 Le/Pe/♂, 3 Pe, 2 Le/P, 2 L, Ranger Mine, Retention Pond 1 spillway, 120°41'S 132°55'E, 11.iv.1989 (Cranston); 18 L, Arnhem Land, East Alligator R., on escarpment, 12°47'S 133°22'E, 15.iv.1989 (Cranston): 17 L, 7 Pe, Arnhem Land, East Alligator R., mid/upper R. on escarpment, 29.v.1988 (Cranston); ♂, Kakadu NP, South Alligator R., Fisher Ck., 13°33'S 132°33'E, 18/ 19.iv.1989 (Cranston); 3♂, Kakadu NP, South Alligator R., Coronation Hill, Gimbat spillway, 13°34'S 132°35'E, 18/ 19.iv.1989 (Cranston).

Molecular material. Qld: 2P♂, L, Bunya, n. Brisbane, Carter Court, South Pine R., 27°21'S 152°56'E, 21.iii.2013, 22 m asl (Krosch) (Mv-SPRP1, 3, SPR2); 2L, Dayboro, n. Brisbane, Lee’s Crossing Rd, North Pine R., 27°12'S 152°48'E, 27.ii.2014, 64 m asl (Krosch) (Mv-NPR1.1, 1.7); L, Numinbah Valley, Nerang R., 28°7'S 153°14'E, 20.v. 2013, 120 m asl (Krosch) (Mv-Ner13); L, Condamine R., Hooloovale Ck., 28°34'S 148°01'E, 30.iv.2012 (Prior) (Mv-Hoo3); L, Warrego R., Dick's Dam, 30°19'S 145°21'E, 2010 (Prior) (Mv-WarD1). NSW: L, Capertee, Glen Davis Rd., Capertee R., 20.i.2013 (Cranston) (Mv-NSW13.6.1). Vic.: P♂, L, Keilor, Maribyrnong R., Brimbank Park Ford, 37°43'S 144°49'E, 1.xi.2006, 25 m asl (Carew) (Mv-MaryA1, MBF1); 2L, Wantirna, Boronia Rd, Dandenong Ck., 37°50'S 145°12'E, 24.x.2006 (Carew) (Mv-DBO1, 5); L, Dandenong, Kidds Rd, Dandenong Ck., 37°59'S 145°13'E, 26.x.2006, 30 m asl (Carew) (Mv-DKI1); L, Pillar's Crossing, Dandenong South, Dandenong Ck., 38°01'S 145°10'E, 26.x.2006 (Carew) (Mv-DPC1); L, Wantirna, Wantirna Rd, Dandenong Ck., 37°50'S 145°13'E, 24.x.2006 (Carew) (Mv-DWA1); L, Sunbury Rd, Jackson’s Ck., 37°35'S 144°44'E, 3.xi.2006 (Carew) (Mv-Jack1); L, Dandenong South, Eumemmerring Ck., 38°01'S 145°13'E, 16.xi.2006 (Carew) (Mv-Eum3); L, Campbellfield, Barry Rd, Merri Ck., 37°40'S 144°58'E, 17.xi.2006 (Carew) (Mv-MBR1); L, Campbellfield, Mahoney’s Rd, Merri Ck., 37°41'S 144°58'E, 17.xi.2006 (Carew) (Mv-MMC1); L, Brooklyn, Princes Hwy, Kororoit Ck., 37°49'S 144°49'E, 10.xi.2006 (Carew) (Mv-KPH1); L, Stony Diversion Drain, Sunshine West, Kororoit Ck., 37°47'S 144°49'E, 9.xi.2006 (Carew) (Mv-KSD2). SA: L, Sawpit Rd., Hindmarsh R., 35º28'S 138º35'E, 3.x.2013, 70 m asl (Krosch & Cranston) (Mv-HR2).

‘divergent NT albitarsis’. NT: P♀, L, Kakadu NP, Kambolgie Ck., 13°30'S 132°25'E, 30–31.vii.2014 (Cranston & Krosch) (Mv-NT14.5.P2, NT14.5.3).

Description. MALE ( Fig. 1 B, 2B). 3.1–3.5 mm.

Head. Ant 792–872 µm; Fl 1–12, 320–360 µm, Fl 13, 456–520 µm. A.R. 1.3–1.6. Palp 340–430 µm. Fr 0, Po 3–5, Clyp sparsely to moderately setose.

Thorax. Sct pale brown to near hyaline, with mid-brown border; otherwise mid-brown, sometimes with reticulate pattern. Other sclerites mid- to dark brown. Laps 3–7, Ac 12–25, Dc 20–40, Pa 3–5, Scts 6–12.

Wing. 1.5–1.9 mm. Sq 4–8, R 0–1.

Legs. All femora mid-brown, sometimes with paler proximal third: all tibiae very pale with distal 1/10 pale to mid-brown: foreleg tarsomeres mid- to pale brown, darker than those on other legs; tarsomeres of mid- and hind legs very pale.

Abdomen. TI and IV pale, TII mid-brown with pale anterior band, TV and VII mid-brown with pale posterior bands, remainder mid- to dark brown.

Hypopygium ( Fig. 2 B). Gcx 180–200 µm, iv elongated, pointed and curved towards posterior. Gst 74–86 µm, about 2/5 (0.39–0.43) Gcx, wide, and blunt apically; crista dorsalis absent.

FEMALE. As male except: 3.1–3.5 mm.

Head. Ant 234–272 µm. Palp 348–488 µm.

Wing. 1.4–2.0 mm. Sq 3–10, R 2–6; R4+5 3–6.

Genitalia. Spermathecae comprising mid-brown, spheroid capsules with long, wide "neck"; and straight or recurved ducts ( Fig. 4 B).

PUPA. 2.5–4.1 mm, pale brown to very pale, almost hyaline; if pale brown may have faint reticulate markings on abdomen.

Cephalothorax ( Fig. 6 B). Slightly rugose dorsally. Th 130–200 µm; width 36–54 µm, broad, flattened, hyaline; scales absent, sometimes granular. Fs long, prominent on frons.

Abdomen. PSB on Il and Ill. Hook row on TII about 1/2 width of segment (0.45–0.61). Small sparse spinule field may be present anterior to hook row. Ls on VIII short, Ls3 no more than 1/10 width of segment (0.08–0.10) ( Fig. 5 E). Ms 120–150 µm, about 1/20 (0.042–0.065) length of abdomen.

4TH INSTAR LARVA. 2.5–4.0 mm. H.l. 450–550 µm pale to mid-brown, with pigmented areas sometimes patchy, and with darker posterior margin; abdomen hyaline; procercus hyaline, sometimes with mid-brown marking.

Head ( Fig. 10 B). Ant 66–76 µm; 1st 40–46 µm; 2–5 26–30 µm; A.R. 1.60–1.85. Md 130–176 µm with smooth inner and more or less crenulate outer margin, pale to mid-brown with distal 1/3 darker. Mentum 104–128 µm, pale brown posteriorly, mid-to dark brown anteriorly; with 6 pairs lateral teeth, 2nd slightly reduced.

Abdomen. Pc 14–20 µm wide, A.s. 300–460 µm.

Etymology. Although Hergstrom (1974) provided no derivation, we infer that the characteristic near-white tarsomeres, especially of the mid- and hind legs, gave rise to the epithet albitarsis . A spelling as albitarsus has been used, including on the labels of Hergstrom’s type series: we consider this a lapsus.

Remarks. Adults of this species can be distinguished from all other Australian Cricotopus by leg colour, with dark femora, pale tibiae, and pale tarsomeres on mid- and hind legs. Pupae can be recognised by the frontal setae on the frons, the hyaline and non-spinose thoracic horn and regular anal macrosetae. Larvae cannot be recognised by a single feature, but by a combination of mandible with crenulate outer and smooth inner surface, mentum with 6 pairs of lateral teeth and the apices of the first lateral mental teeth posterior to the apex of the median tooth, plus the dark pigment restricted to the apical mandible only.

From Freeman's (1961) description of pinned Australian specimens, this species appears to be his C. albitibia , although his description differs in having the AR as 1, i.e., much lower than the range of specimens measured in this study. Calculations of the antennal ratio from dried material is notoriously error-prone and we do not consider it significant. One male from Lake Monger, WA, labelled " Cricotopus albitibia , det. P. Freeman", from the British Museum (B.M.1955-478, slide-mounted by P. S. Cranston) was studied. This, one of the six male specimens from the location given in Freeman's description, fits the description of C. albitarsis above, with an AR of 1.5, as does the colour of five pinned specimens from the same locality also in A.N.I.C..

The type location of C. albitibia is Sierra Leone in west Africa (Walker, 1848), but the species was redescribed by Lehmann (1979) from specimens from east Zaire (=D.R. Congo). Lehmann's species as re-described differs from our Australian material in the following: adult leg pattern, with C. albitibia having pale bands on all legs; adult thorax pattern, with C. albitibia having brown vittae or "mesonotal stripes" and the pupal thoracic horn, that of C. albitibia being long and narrow. The larva of C. albitibia is undescribed. For our study 3 unreared larvae, 1 pharate male, 1 adult male and 3 adult females of C. albitibia from Ethiopia, collected and identified by Prof. A. Harrison were examined. The specimens were uncleared before mounting, and thus several features were not visible. The larvae are larger than those of C. albitarsis , one having antennal length 210 µm with AR = 2.10, which is outside the range of all Australian Cricotopus (1.29–2.00), and appear to differ also from C. albitarsis in the complex ‘chunky’ development of a darkened mola resembling a broken tooth. The single Ethiopian pupa has a hyaline, blade-shaped thoracic horn, tapering towards the apex, spinules on TIII and IV densely covering the tergite and the hook row is very broad, 70% the width of TII, again outside the range of all Australian species (0.30–0.63). Adults appear very similar, including in the shape of the inferior volsella. However, the larva and especially the pupa appear incompatible with C. albitarsis . Thus we consider C. albitibia from Australia to have been misidentified by Freeman.

Examination of Hergstrom's proposed holotype and 2 paratypes of " C. albitarsis sp.nov ", now in the A.N.I.C., showed that the legs have pigmented femora, the distal ends of the tibiae also are pigmented, and the tarsomeres of the forelegs are mid-brown (as on the specimens described here), although Hergstrom describes the legs as "all legs pale yellow", and the key states "Tibiae and tarsi completely without dark pigment", without mentioning the colour of the femora. She does not describe the pupa and larva. Other character states fit this species, and it appears to be Hergstrom's manuscript name C. albitarsis , which is validated here with her authorship.

Molecular evidence for the identity of ‘albitarsis’ comes from mature pupae from s.e. Queensland and Victoria close to identical to unreared larvae from across the eastern Australian range of the morphospecies. The situation regarding 2 specimens from Kambolgie Ck in southern Kakadu N.P. is uncertain. The female pupa (Mv- NT14.5.P2) conforms to the diagnoses here for C. albitarsis . The sole larva (Mv-NT14.5.3), is near identical to the pupa on molecular evidence, and keys to C. albitarsis but differs in the darker head capsule, the distinct Lauterborn organs and dark apex to the mandible less contrasting to a brown basal part. Unfortunately neither specimen is perfect – the pupa appears to have only 2 macrosetae on one side and on the other they are broken at the base and the larva has a worn/damaged median mentum. No additional candidates exist in older morphological material from the Alligator River Region. Molecular data indicate that these two specimens are divergent from C. albitarsis and lie as sister to the clade ‘ albitarsis + wangi’ (Krosch et al., submitted), much as implied by the morphology. Probably this constitutes a cryptic species but without further material with DNA associated, we will term the taxon ‘divergent N.T. albitarsis’.

C. albitarsis is a widespread species across the continent, absent only from Tasmania . It tolerates elevated water temperatures and eutrophic to mine-contaminated standing and running waters, including the country’s largest rivers and those salinated. This species occurs also in relatively unimpacted waters, as evidenced by some molecular collection sites.

Figures

FIGURE 1. Cricotopus adult males. Columns (left to right): legs, anterior to posterior; thorax; dorsal abdomen. A. C. acornis, B. C. albitarsis, C. C. annuliventris, D. C. brevicornis, E. C. conicornis, F. C. hillmani, G. C. parbicinctus, H. C. tasmania, I. C. varicornis.

FIGURE 2. Cricotopus male genitalia, part, (inset variations in inferior volsella above, gonostylus below). A. C. acornis, B. C. albitarsis, C. C. annuliventris, D. C. brevicornis, E. C. conicornis, F. C. hillmani.

FIGURE 4. Cricotopus female. Spermathecae. A. C. acornis, B. C. albitarsis, C. C. annuliventris, D. C. brevicornis, E. C. conicornis, F. C. hillmani, G. C. parbicinctus, H. C. tasmania, I. C. varicornis.

FIGURE 5. Cricotopus pupa. Frons: A. C. wangi, B. C. howensis, C. C. parbicinctus. Lateral segment VIII: D. C. wangi, E. C. annuliventris, F. C. tasmania. Anal lobe: G. C. wangi. Anterior tergites: H. C. brevicornis, I. C. varicornis.

FIGURE 6. Cricotopus pupa, thorax and thoracic horns. A. C. albitarsis, B. C. annuliventris, C. C. brevicornis, D. C. conicornis, E. C. hillmani, F. C. howensis, G. C. parbicinctus, H. C. tasmania.

FIGURE 10. Cricotopus larva, mentum, mandible, antenna. A. C. acornis, B. C. albitarsis, C. C. annuliventris, D. C. brevicornis.