Paradexamine narluke J. L. Barnard 1972

Paradexamine narluke

DESCRIPTION (of male; female unknown). — Lateral cephalic lobe rounded, head with distinct anteroventral definition at base of antenna 2, rostrum of medium length and apically blunt; article 1 of antenna 1 ventrally setose, otherwise simple, article 2 about 1.3 times as long as article 1, apically simple and scarcely setose ventrally, flagellum about 1.8 times as long as peduncle, flagellum of antenna 2 about 1.7 times as long as peduncle, article 4 of peduncle elongate and anteriorly setose, with 3 sets of lateral spines, article 5 about half as long as 4; article 3 especially produced ventrally; mandibles with large spines, 2 on right, 3 on left plus setule, molar heavily triturative, accessory bulges numerous and sharp, both molars with ordinary setae and 1 ragged seta; outer lobe of lower lip with 3-4 long cones, mandibular lobes blunt when flattened, otherwise axially curled so as to appear tapering; palp of maxilla 1 small, much shorter than outer plate, very narrow, bearing 2 apical setae, no cones; inner plate of ordinary size, naked; plates of maxilla 2 narrow, appressed, inner reaching about 70 percent along outer, inner with definite truncate apex and 2 setae, then 2 subterminal embevelments each with seta; inner plates of maxilliped vestigial, each bearing spinule, outer plate of ordinary to slightly tumid dimensions, bearing simple spines, palp thin, scarcely exceeding outer plate, palp article 4 of medium elongation; coxa 1 expanding slightly apically, anteriorly naked, with weak indication of anterior acclivity highly distad, ventral setae of coxae 1-4 sparse and short, posterior margins of 1-4 naked, coxae 2-3 softly rectangular, coxae 5-6 ventrally spinose; gnathopods stout, gnathopod 1 with article 6 about 0.84 times as long as article 5, about 0.90 times on gnathopod 2, fifth articles broad, expanding apically, palms oblique, extremely finely castellate, dactyls smooth proximal to main inner tooth, palmar faces on gnathopod 1 with oblique row of 2 pectinate and 2-3 simple setae, anteriorly with sets of 6 and 3 setae, on gnathopod 2 oblique row with 2 pectinate and 2 simple setae, anterior sets with 5 and 2 setae each; pereopods 1-5 of regular stoutness, with numerous blunt spines, ratio of articles 4-7 on pereopods 1-2 about 24:27:36:20, article 2 of pereopod 3 of medium breadth, with regular posteroventral lobe; article 2 of pereopod 4 circulopyriform, posteroventral lobe weak but distinct, bearing spine, posterior margin weakly setulose; article 2 of pereopod 5 ovatorectangular, posterior margin strongly serrate and bearing thick short spines, posteroventral region slightly tumid but lobe not distinctly projecting, also spinose, ratio of articles 4-7 about 24:36:34:15; pleonal epimera 1-2 with lateral ridge, epimeron 1 with tiny posteroventral tooth, 2-3 with medium sharp tooth, epimeron 3 especially serrate posteriorly and bearing 5-6 weak posterior setae, epimera 1-2 with increasingly weaker serrations and fewer setae, epimeron 1 anteroventrally with 1 seta, 1 spinule, 1 facial spinule, epimeron 2 with 1-2 ventral spines, broadly spread row or group of 3-4 facial spines, epimeron 3 with 4 ventral spines; pereonite 7 dorsally smooth; pleonite 1 with extremely weak dorsal tooth, pleonites 2-4 with sharp and low dorsal tooth, sharp side tooth, pleonite 4 with spine on lateral ridge, pleonites 5-6 (fused) with 2 short spines in tandem; dorsal margin on peduncle of uropod 1 evenly spinose, lateral base of peduncle with 1 stout spine, rami of uropod 3 with several setae; telson flat, apices narrow, bearing 3-5 weak, diverse serrations and 1 small apicolateral spine, lateral margins with 5-6 medium spines in tandem, none paired; cuticle of epimera and urosome covered densely with crescent slits lacking setules, cuticle of coxa 5 and article 2 of pereopod 3 covered densely with setules apparently arising from slit-pits, pits and setules rare to absent elsewhere.

HOLOTYPE. — WAM, male, 3.3 mm. Unique.

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

RELATIONSHIPS. — Paradexamine narluke has a superficial resemblance to P. thadalee, because of the presence of either slit-pits or numerous setules on the cuticle in several places, but otherwise the two species are in completely different species flocks because of the absence of a lateral tooth on pleonite 4 in P. thadalee. Paradexamine narluke further differs from P. thadalee in the well-defined head at the base of antenna 2, the blunt mandibular lobe of the lower lip, the posteriorly naked coxae 1-3, the broad ovatopyriform article 2 of pereopod 5, the lack of tightly bundled rows of facial spines on epimera 2-3, and the flat telson.

Paradexamine narluke appears to have more characters in common with P. muriwai from New Zealand than with any other known species. The Australian species differs from P. muriwai in the absence of teeth on pleonite 1, the much smaller body, the slightly smaller inner plate of the maxilliped, the presence of only 1 terminal spine on each lobe of the telson, the short palp of maxilla 1, the shorter inner plate of maxilla 2, the posteriorly naked coxae 1-3, and the anteriorly naked coxa 1.

Paradexamine windarra has some resemblance to P. narluke, but the latter has blunter dorsal teeth, none on pereonite 7 and pleonite 1, stout epimeral spines and facial spines on epimeron 2, anteriorly naked coxa 1, more oblique palms of the gnathopods, nonfeathered, nonstriate locking spines on pereopods 1-2, and blunt spines otherwise on article 6, poorly setose coxae 2-4, no distinct lobe on article 2 of pereopod 5, and several other minor differences.

Paradexamine narluke differs from P. frinsdorfi in the short inner plates of the maxillipeds, the anteriorly naked coxa 1 with the vestigial acclivity moved highly distad, no posterior spines on coxae 2-3, the broadness and nearly lobate article 2 of pereopod 5, the facial spines of epimeron 2, and the absence of dorsal teeth on pereonite 7 and pleonite 1.

Paradexamine lanacoura has some resemblances to P. narluke, but the latter differs from P. lanacoura in the blunt rostrum, the absence of setules on the accessory bulges of the mandible, the anteriorly naked coxa 1, no posterior spines on coxa 2, the poorly developed posterior setae of the epimera and the castelloserrate margins, the facial spines on epimeron 2, the flat telson, the simple article 1 of antenna 1 (even in the male of P. lanacoura a process occurs on article 1), and the absence of teeth on pereonite 7 and pleonite 1.

Paradexamine narluke differs from P. goomai in the presence of facial spines on epimeron 2, the better-developed article 2 of pereopod 5, the unextended coxa 3 and weak setae of coxae 2-4, the distinct locking spines of pereopods 1-2, the more distad ornaments on the pereopodal dactyls, the small inner plate of the maxilliped, the distally expanded coxa 1, the thin plates of maxilla 2, and the thin and short palp of maxilla 1.

MATERIAL. — The type-locality (1).

DISTRIBUTION.—Southwestern Australia, intertidal.