Marmenuera tillyardi, Dean & Forteath & Osborn, 2008

Dean, J. C., Forteath, G. N. R. & Osborn, A. W., 2008, Marmenuera, a new genus of leptophlebiid mayfly (Insecta: Ephemeroptera) endemic to Tasmania., Memoirs of Museum Victoria 65, pp. 43-50 : 44-47

Marmenuera tillyardi sp.nov.

Figures 1–16

Genus W sp.AV1 Dean 1999, p. 86, figs 239–41.

Types. Holotype: Male imago (reared from nymph), Tasmania, un-named creek flowing into Lake Pedder (Tasmap 1:25 000 series, Serpentine 4026, Grid reference 55G 4184 52606), collected 28 Jan 2006, emerged 30 Jan 2006, A. Osborn and N. Forteath ( MV, T-20000) . Paratypes: Male imago and female imago (both reared from nymph), same location as holotype, collected 28 Jan 2006, emerged 19 Mar 2006 and 23 Feb 2006 respectively, A.Osborn & N.Forteath ( MV, T-20001 and T-20002 respectively); male imago and female imago (both reared from nymph), same location as holotype, collected 5 Jan 2006 and 28 Jan 2006 respectively, emerged 14 Jan 2006 and 13 Feb 2006 respectively, A.Osborn and N.Forteath ( ANIC) .

Material examined. Tasmania. 6 MI, 12 FI (all reared from nymphs), un-named creek flowing into Lake Pedder (type locality), 28 Jan 2006, emerged various dates, A. Osborn and N. Forteath; 3 MI, 1 FI (all reared from nymphs), same location, 25 Jan 1998, N. Forteath; 1 FI (reared from nymph), same location, 23 Feb 1998, N. Forteath; 1 MI, 1 FI (both reared from nymphs), same location, 4 Mar 1998, N. Forteath; 2 MI, 2 FI (all reared from nymphs), same location, 5 Jan 2006, A. Osborn and N. Forteath; 1 MS, 1 FS (both reared from nymphs), 4 N, same location, 27 Dec 1997, N.Forteath; 2 N, Piney Creek, Heamskirk Rd, 27 Oct 1994, MRHI; 1 FI, 1 FS (both reared from nymphs), Lake Pedder , Trappes Bay , 4 Mar 1998, N. Forteath; 1 MI, 2FI (all reared from nymphs), Lake Pedder , Serpentine Arm, Apr 2005, N.Forteath .

Description. Male imago: Length: body 8.8–10.2 mm., forewing 8.8–10.1 mm., caudal filaments 12.4–14.2 mm. Eyes: upper lobes pale pink/brown, separated mesally by a distance approximately 1/8 of the diameter of the upper lobe in dorsal view; lower lobes grey. Thorax: medium-dark brown; pronotum with narrow raised carina along median line, dark brown markings medially on posterior half of segment, dark brown along lateral margins and curved dark brown band parallel to lateral margin approximately midway between margin and medial carina. Legs: predominantly medium brown, tending to paler in apical half of tibiae and tarsi; all femora with two broad dark brown bands, one just beyond midlength and the other sub-apical; tarsal claws similar, each claw with terminal sclerotised hook and opposing ventral process. Forewing (fig. 1): membrane hyaline, stigmatic region opaque, white; costal crossveins in basal half of wing heavily suffused with dark brown, subcostal and R 1 – R 2 crossveins in basal half of wing less strongly suffused with dark brown, crossveins near MA fork not suffused with brown. Abdomen: terga generally reddish-brown with dark brown markings, tergum 6 with four conspicuous dark brown longitudinal bands extending over most of the segment (fig. 5), segment 7 with similar bands but restricted to anterior half of the segment, segment 8 with dark markings only adjacent to the anterior margin; sterna reddish brown, inconspicuous paler markings on segments 2-5 (fig. 6), darker brown markings poorly defined. Genitalia (figs 7, 8): penes lobes fused basally, widely separated apically; each lobe relatively broad and approximately parallel-sided, apically truncate, outer margin somewhat angular just before apex; three moderate sized ventral spines close to inner margin posterior to where the lobes separate.

Female imago. Length: body 10.1–12.2 mm; forewing 10.0– 11.8 mm; caudal filaments 13.4–16.4 mm. General colour similar to male imago. Forewing: membrane slightly opaque; costal, subcostal and R 1 – R 2 crossveins all surrounded by suffusion of dark brown, more strongly developed than in male. Abdomen: medium reddish-brown, terga with darker brown markings, sterna medium reddish-brown, no strong markings; sternum nine deeply cleft (fig. 10). Subimago. Wings pale fawn/yellow, brown blotches and/or suffusions similar in distribution and intensity to corresponding imago. Mature nymph. Body length ranging from about 10 to 13 mm.; antennae about half length of body; cerci about 1½ times length of body, terminal filament a little longer. General colour yellow with dark brown markings; abdomen with conspicuous pattern of dark brown and yellow, abdominal segments 6 and 9 darker than remaining segments (fig. 11); all legs with dark banding. Mouthparts: labrum (fig. 12) a little broader than clypeus; maximum width 1.7–1.9 times length along median line; maximum width at about 3/4 labrum length, basal to this the lateral margins relatively straight and diverging; anterior margin shallowly concave, with five well developed medial denticles; single row of setae close to frontal edge of labrum, sub-apical setal fringe also consisting of a single row set back from anterior margin at about 0.9 labrum length. Legs relatively slender; forefemora length 3½–4 times width ( Fig. 13 ), outer margin with moderate number of short, spine-like setae and also longer, hair-like setae; foretarsus (fig. 14) with 30–40 ventral spines; tarsal claws smooth, without ventral teeth. Postero-lateral spines on abdominal segments 7 (small) and 8-9 (relatively large); posterior margins of abdominal terga with series of large, conspicuous spines interspersed with the occasional shorter spine (fig. 15). Gills lanceolate, lateral tracheae moderately developed (fig. 16).

Etymology: The species is named for R.J.Tillyard, who first recognised that this was probably an undescribed species (see below).

Remarks. When describing Atalophlebia ida, Tillyard (1936) referred to specimens from Cradle Mountain which were smaller and less spotted than the type series. It now seems likely that these belong to the species herein described as M. tillyardi , and Tillyard’s decision not to describe the male imago of A. ida based on the Cradle Mountain material has been proven taxonomically astute.

Scholes (1961) recommended that the imago and subimago of A. ida should be referred to as the “Large Speckled Spinner” and “Large Speckled Dun” respectively, and we suggest that “Lesser Speckled Spinner” and “Lesser Speckled Dun” are appropriate common names for the imago and subimago of Marmenuera tillyardi . This reflects both the smaller size of the new species and the reduced wing pigmentation.

Figures

Figures 1–4. Marmenuera tillyardi. Male imago: 1, forewing; 2, hind wing. Female imago: 3, forewing; 4, hind wing.

Figures 5–10. Marmenuera tillyardi. Male imago: 5, abdomen, dorsal; 6, abdomen, ventral; 7, penes, dorsal; 8, penes, ventral, slide preparation; 9, foretarsal claw. Female imago: 10, sternum nine.

Figures 11–16. Marmenuera tillyardi. Nymph: 11, abdomen, dorsal; 12, labrum; 13, forefemur; 14, foretarsus; 15, posterior margin of abdominal segment four; 16, gill, abdominal segment four.