Tillyardophlebia dostinei, Dean & Suter, 2004

Dean, J. C. & Suter, P. J., 2004, Descriptions of new species and a new genus of leptophlebiid mayflies (Insecta: Ephemeroptera) from the Northern Territory, Australia, Memoirs of Museum Victoria 61 (1), pp. 111-118 : 116-117

Tillyardophlebia dostinei sp. nov.

Figures 35–47

Type material. Holotype: male imago (reared from nymph), Rockhole Mine Creek, Kakadu National Park , Northern Territory, 13˚30 ’ S 132˚30 ’ E, 24 Jun 1995, P. Dostine ( NMV T-18493).

Paratypes: male imago (reared from nymph; wings, legs and nymphal exuvia mounted on slide, labelled specimen 01), Rockhole Mine Creek, Kakadu National Park, Northern Territory, 13˚30'S 132˚30'E, 24 Jun 1995, P. Dostine ( NMV T-18494); male imago, 2 female imagos (all reared from nymphs), Rockhole Mine Creek , Kakadu National Park , Northern Territory, 13˚30'S 132˚30'E, 31 May 1995, P. Dostine ( NMV T-18495– T-18497) .

Other material examined. Northern Territory. 1MSI (reared from nymph), Rockhole Mine Creek, Kakadu National Park , Northern Territory, 13˚30'S 132˚30'E, 24 Jun 1995, P. Dostine; 3N, Rockhole Mine Ck, 2 May 1990, D. Cartwright .

Description. Imago. Length of male: body 5.6–6.5 mm, forewing 6.0– 6.6 mm; Length of female: body 5.5–5.6 mm, forewing 6.0– 6.4 mm. Eyes of male with upper lobes brownishpink, in contact dorsally, lower lobes black. Thorax orange-brown. Forewing with membrane hyaline (Fig. 35); costal and subcostal cells in apical third of wing translucent, whitish; length-width ratio 2.8–3.0; costal crossveins absent or weakly developed basal to the bulla, 10–15 distal to the bulla; MA forked at 0.37–0.39 wing length; MP 2 attached by crossvein to MP 1 at about 0.18 wing length; ICu 1 linked to CuA-CuP crossvein, ICu 1 and ICu 2 weakly diverging as wing margin approached. Hindwing 0.20–0.22 length of forewing; costal margin convex at about midlength, relatively straight basal and distal to midpoint (Fig. 36); vein Sc joining costal margin a little less than 0.9 wing length; hindwing with 3–5 costal crossveins and 5–6 subcostal crossveins, all weakly developed. Legs pale, not banded, but slightly darker brown at apex of femur and tibia; tarsal claws dissimilar, one claw with an apical hook and without an opposing ventral flange, the other large, pad-like (Fig. 39); forelegs of male with ratios of segment lengths 0.72–0.73; 1.00 (2.4 mm); 0.07–0.08; 0.31–0.32; 0.29–0.30; 0.22; 0.08–0.09. Abdomen predominantly pale yellow, restricted dark brown markings on segments 1–6, more strongly developed markings on segments 7–9 (Figs 37, 38). Male genitalia with claspers three-segmented, narrowing gradually at about one-third length (Fig. 40); penes extending beyond narrowing of claspers, lobes moderately broad, widely separated in apical two-thirds and fused in basal third; each lobe with a stout, inwardly directed subapical spine and a ventral longitudinal ridge (Figs 41–43). Female ninth sternum with posterior margin entire, strongly convex, protruding beyond apex of segment 10 (Fig. 44). Mature nymph. Head prognathous. Mouthparts: Clypeus with lateral margins slightly diverging to anterior. Labrum clearly broader than clypeus, width about 2.4 times length along median line; 2 setal fringes close to anterior margin, each fringe extending across more than half width of labrum; anterior margin with broad central notch, the base of which is concealed beneath an overhanging canopy (Fig. 45). Mandibles with incisors slender. Maxillae with subapical row of about 25 pectinate setae. Legs with tibiae and tarsi relatively slender (Fig. 46); tibiae with ventral spine-like setae relatively dense right to apex; tarsi with 10 or fewer ventral spine-like setae, relatively uniform in length; tarsal claws with ventral teeth, progressively larger apically. Abdominal segments without setae on lateral margins, strongly developed posterolateral spines on segments 2–9. Gills present on abdominal segments 1–7, each gill narrowly lanceolate without lateral tracheae (Fig. 47).

Etymology. The species is named for Peter Dostine, who collected the type material and associated nymphs with adults.

Remarks. This species was not included in the original keys to mayflies of the Alligator Rivers region presented by Suter (1992). The nymph has previously been designated Tillyardophlebia sp. AV8 ( Dean, 1999), albeit with a comment that the species should perhaps be placed in a new genus. While we have opted to retain the species in Tillyardophlebia pending completion of further study of two undescribed Queensland species and a detailed phylogenetic analysis, we are of the opinion that these three northern Australia species will eventually be transferred to a new genus. The nymphs of the species from northern and southern Australia are very similar, with no obvious characters to justify generic separation. In the imagos, however, there are clear differences in the structure of the male genitalia. The species from south-eastern Australia form a monophyletic group with long, narrow and widely separated penes lobes, each lobe bearing a large curved ventral spine ( Tillyardophlebia sensu stricto). Species from northern Australia have more robust penes lobes, which are fused either in the basal third or along most of their length, and each lobe has a single subapical spine.

Although confirmed material of this species has only been collected from the type locality, it is probably more widely distributed. We have examined nymphs from Manning Gorge in north-western Australia which we believe are conspecific .

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