Tethygeneia tulkara J. L. Barnard 1972

Tethygeneia tulkara

DESCRIPTION (of female).—Rostrum large, long, curved down, apically blunt, lateral cephalic lobe broad, shallow, quadriform, defined below by weak but sharp incision, anteroventral margin bulbous, rounded; antenna 2 about half as long as body, antenna 1 only about 60 percent as long as antenna 2; eye of medium size, purple core surrounded by 1–2 layers of clear ommatidia in alcohol; flagellum of antenna 1 twice as long as peduncle but flagellum of antenna 2 thrice as long as its peduncle, flagella thin; accessory flagellum articulate, broader than long, sharply trapezoidal; middle of primary flagellum on antenna 1 with alternate articles slightly swollen and bearing 1 or 2 aesthetascs; articles of flagellum on antenna 2 even; mandibular molars triturative, each with ragged seta, spine row on right with 3 main spines, a fourth smaller spine toward molar (in male 2 main spines, a third smaller spine toward molar, a fourth even thinner spine between 1 and 2), left with 4 main spines, pair of smaller spines between 1–2, and 1 smaller spine between 2 and 3 (male, 4 main spines, pair of smaller spines between 1–2 and 2 smaller spines past spine 4 toward molar), left lacinia mobilis serrate and clearly distinct, right composed of 2 serrate spines, 1 bearing cusp and appearing as membrane; mandibular palp with article 2 about twice as broad as 3, latter falcate and only 55 percent as long as 2, bearing 2 apical spines, 2 slightly larger, then 3 more proximal spines, no basofacial seta, article 2 with about 5 spines near apex; lower lip lacking inner lobes, mandibular lobes subtruncate and apically fringed; inner plate of maxilla 1 bearing 1 giant apical seta and 3 smaller medial setae on distal half; inner plate of maxilla 2 apically and subapically fringed with small setae, midmedial margin with 2 enlarged setae in tandem; inner plate of maxilliped with apicolateral spine separated from 2 medioapical spines by gap and hollow (medialmost spine much smaller than in T. elanora), outer plate with facial setules in 1 row and a few scattered, article 2 of maxillipedal palp especially broad; coxae 1–4 lacking posterior setules, posterior lobe of coxa 4 softly rounded (coxae 1–4 more shallow than in T. elanora and lobe of coxa 4 thus somewhat extended); article 2 of gnathopods 1–2 scarcely setose posteroventrally, hands of gnathopods long, thin, subrectangular, palms evenly oblique, article 5 of gnathopod 1 about 55 percent the length of article 6, about 50 percent on gnathopod 2, posterior margin of article 5 on gnathopod 1 narrowly triangulate but softly, on gnathopod 2 produced to long lobe guarding posterior proximal third of hand (differing from T. elanora in presence of posterior spine on hand instead of seta, comb rows on article 5 of gnathopod 2 sparse); locking spines of pereopods 1–2 composed of 2 heavy spines slightly truncate apically (with triggers) and 2 short setae, dactyls each with distal constriction, nail, long sharp seta, and shorter sharp facial seta guarding constriction, inner margin of dactyl smooth; locking spines of pereopods 3–5 similar; article 6 apically smooth on pereopods 3–5; coxa 5 almost evenly lobate, coxa 6 with large quadriform posterior lobe; article 2 of pereopods 3–5 broadly expanded, articles 4–7 slender, article 2 on pereopod 5 bearing facial setules-spinules only anterior to main anterofacial ridge; epimeron 1 softly rounded behind, with weak declivity at posteroventral corner, epimeron 2 with sharp shallow tooth and protruding posteromiddle margin, epimeron 3 similar but protrusion deeper and tooth smaller, ventral margins of epimera lined with spines in sets of singles (epimeron 1 with 5 spines, 2 with 4, 3 with 5); no dorsal teeth; uropod 3 lacking any stout peduncular spine; pleonite 6 with row of tiny denticles anterodorsal to base of uropod 3 (and pleonites 1–5 with pair of dorsal longitudinal rows of these); telson flat, broad, cleft more than halfway, apices slightly rounded, broad, smooth, lateral margins of lobes with 2 pairs of partial sets of setules; cuticle with rare setule.

MALE.—Like female but antennae more elongate and no male yet discovered bearing calceoli; eyes slightly larger than in female; accessory flagellum with main elongate spine reduced to size similar to other setae; antennal peduncles developing groups of setules; formula for aesthetascs and swollen articles generally similar to female; gnathopods slightly enlarged, hands slightly more elongate and ovate than in female and lobes on article 5 of both gnathopods slightly more protuberant; posterior setae of article 6 on pereopods 1–2 not plumose (no terminal male apparently found); epimeron 1 bearing only 2 ventral spines.

EXAMPLES OF FLAGELLAR FORMULAE (of males and females; see symbols in T. elanora).—Flagellum of female antenna 1: (1–2):2:3:0:2:0:2:0:1:0:1:0:1:0:1:0:0:0:0 (terminus). Male, left: 2:2:2:0:2:0:2:0:2:0:2:0:2:0:2:0:3:0:0:0: (broken); right:2: 3:3:0:2:0:2:0:2:0:2:0 (broken).

ILLUSTRATIONS.—The strong similarity of most attributes of this species to T. elanora has obviated repeating most of the drawings.

HOLOTYPE.—WAM, female, 4.5 mm.

TYPE-LOCALITY.—JLB Australia 3, Sugarloaf Rock, Cape Naturaliste, Western Australia, intertidal, wash of common seaweeds, 1 September 1968.

RELATIONSHIP.—This species differs from the three species T. elanora, T. nalgo, and T. waminda in the presence of stout spines in the locking set on pereopods 1–2. Though T. tulkara may be distinguished from T. nalgo and T. waminda by the plain cuticle, I have not found any other character to distinguish T. waminda and T. tulkara except the locking spines on pereopods 1–2; specimens missing the apices of these pereopods have remained unidentified if the cuticle is unpitted.

Tethygeneia tulkara bears a gradational resemblance to G. microdeuteropa (Haswell) because of the stout locking spines on pereopods 1–2, but, otherwise, it differs by the smaller, more even gnathopods 1–2, the long rostrum, the smooth cuticle, and the fairly simple flagella and pereopodal dactyls. Juveniles of the two species are difficult to separate grossly without checking the rostrum and gnathopods, but the eyes of G. microdeuteropa are much more densely pigmented and more circular than those of T. tulkara, and this appears to be a possible way to separate large quantities of specimens rapidly.

MATERIAL.—JLB Australia 3 (17), 5 (14), 6 (3), 11 (13), 13 (18), 14 (9).

DISTRIBUTION.—Southwestern Australia, intertidal.