Goratelson woka (Barnard 1974)

Stenothoe woka

DESCRIPTION OF FEMALE.—Lateral cephalic lobe strongly projecting, mammilliform, rounded apically, anteroventral corner of head with double rugose projection; prcbuccal mass moderately bulky, protuberant, epistomal and labral parts weakly defined by notch, epistomal part forming blunt extension exceeding round hump of midcephalic keel; mediodistal part of article 1 on antenna 1 strongly extended; accessory flagellum apparently absent or represented by seta near subcuticular sclerites; lobes of upper lip ordinary, extending unequally; inner plate of maxilla 1 asymmetrically ovate, bearing one long seta, palp with five or six marginal spines extending less than halfway mediobasally, apicolateral margin of palp not beveled, article 1 not tumid; inner plate of maxilla 2 weakly subfalciform, bearing about three medial setae and one long apical seta, outer plate thin and elongate, slightly curved inward, setal spines long; inner plates of maxilliped of medium length and breadth, subrectangular, bearing four apical setae, outer plate of ordinary size, article bearing outer plate lacking facial setae; coxae 1–3 of ordinary dimensions, coxa 4 large and posterodorsally extended, ventral margin excavate; article 5 of gnathopod 1 with narrow posterior lobe, hand long, palm oblique, dactyl with one outer seta, inner margin lacking tooth, anteromedial margin with group of three transverse setae and one other seta; gnathopod 2 ordinary, article 4 with blunt posterodistal corner, palm oblique but well marked by shape from posterior margin of hand, dactyl lacking tooth and outer setae; pereopod 2 grossly stouter and shorter than pereopod 1, articles 5–6 with posterior granules, pereopod 3 resembling pereopod 1, pereopods 4–5 stout and granulate like pereopod 2, article 2 of pereopod 4 much narrower than that of pereopod 5 but broader than article 2 of pereopod 3, lacking anterolateral facial ridge, article 2 of pereopod 5 with anterofacial ridge diverging from anterior margin, locking spine pair of all pereopods distinct from adjacent marginal spines, small on pereopods 1 and 3, large on pereopods 2, 4, 5, blunt or sharp respectively, distal setule of pereopods variable, recumbent and membranous on pereopods 2 and 5, thin and erect on pereopod 4, thick and slightly erect on pereopods 1 and 3, but seta often erect on pereopods 2 and 5; peduncle of uropod 1 lacking ventral tooth, distolateral margin with one apical spine, outer ramus slightly shortened, bearing two spines, inner ramus naked, outer ramus of uropod 2 slightly shortened, bearing one spine, inner ramus naked; uropod 3 with one large distal spine on peduncle, one distal setule on article 1 of ramus; telson long, narrow, bearing two spines basolaterally, distally with four setules; epimera 1–3 each with softly subquadrate posteroventral corner, epimeron 1 with weak posterior serrations, no ventral setules; pleonite 4 especially elongate and bearing dorsolateral crest on each side.

Dactyls of pereopods have tiny, scarcely resolvable notches (oil immersion) on the inner margins.

MALE.—Eyes and gnathopod 2 slightly larger than in female, defining spines of gnathopod 2 laterally three in number, dactyl of gnathopod 1 lacking outer seta.

JUVENILE (1.1 mm).—Spines are absent on rami of uropods 1–2, on all of uropod 3 and on the telson; the granules on pereopods 2, 4, 5 are very weak.

VARIATION.—Juvenile, 1.8 mm, Shepherd 3: the telson has one spine on each side, only the outer ramus of uropod 1 has a spine and the other rami of uropods 1–2 are naked, but the main aberrancy is that the outer ramus of uropod 2 is 85 percent as long as the inner ramus.

HOLOTYPE.—WAM 133–71, female, ovigerous, 2.7 mm.

TYPE-LOCALITY.—JLB Australia 11, Middleton Beach, Albany, Western Australia, intertidal, wash of algae and rocks, 30 September 1968.

DISTRIBUTION.—Pearson Islands, South Australia, 5–12 m; Middleton Beach, Albany, Western Australia, intertidal.

Wallametopa, new genus

DIAGNOSIS.—Article 2 of pereopod 3 rectolinear, article 2 of pereopods 4 and 5 expanded; palp of maxilla 1 uniarticulate; mandible lacking palp; article 5 of gnathopod 1 highly elongate, hand short, narrow, palm absent, dactyl thick and short; gnathopod 2 much larger than gnathopod 1, hand ovate, palm oblique and fitting most of posterior margin of hand.

TYPE-SPECIES.—W. cabon, new species (here selected).

RELATIONSHIP.—The type-species of this genus fits Parametopa Chevreux in keys published by Shoemaker (1955) and J. L. Barnard (1969a) but differs in two important characters: the elongation of article 5 on gnathopod 1 and the enlarged gnathopod 2. Wallametopa appears to be more primitive than Parametopa in the possession of these characteristics and one might suggest that the warm-temperate Atlantic Parametopa is a descendant of organisms similar to Wallametopa.

Classification in Stenothoidae remains cloudy (J. L. Barnaid, 1969a). Only three classes of characters have been used in this century to divide the family into genera (prior to the inclusion of Thaumatelsonidae in Stenothoidae, see J. L. Barnard, 1972a). The classes of characters are the condition of the mandibular palp, first maxillary palp, and article 2 of pereopods 3–5. In the case of Wallametopa the keys of Shoemaker and Barnard usefully delineated the close relationship to Parametopa but did not show the observer that other genera, such as Metopa and Stenothoe have species with the odd gnathopod 1 seen in Parametopa and Wallametopa. The tendency to develop a linear gnathopod 1 is seen also in several other genera. The further relationships of Parametopa and Wallametopa await a monographic study of stenothoid genera in which an evaluation of the mouthpart structures in relationship to gnathopods and perhaps other characters can be made.