Paradexamine churinga J. L. Barnard 1972

Paradexamine churinga

DESCRIPTION (of female). — Lateral cephalic lobe rounded-quadrate anteriorly, often with flange, head with scarce anteroventral definition at base of antenna 2, rostrum sharp, attenuate; article 1 of antenna 1 with weak ventral protrusion, spines thin and arranged in 2-3 groups of 2-5 each, article 2 about 1.2 times as long as article 1, apically simple and lacking thick spines ventroproximally, flagellum about 1.8 times as long as peduncle; flagellum of antenna 2 twice as long as peduncle, multiarticulate; mandibles bearing 2 large spines on right, 3 on left, molar moderately to strongly ridged, ragged seta each side, weaker on left, regular setae only on right, accessory bulge weak, rounded; outer lobe of lower lip bearing 1 long, 1 medium cone plus accessory facial cusp at base of long cusp, mandibular lobes thin, apically upturned; palp of maxilla 1 large, broad, or medium, exceeding or surpassing spine bases on outer plate, bearing 1 small apical cone and medial and terminal setae, inner plate of normal size and naked; inner plate of maxilla 2 narrower than outer, both appressed, inner with apex strongly oblique, outer scarcely curved, inner reaching 75 percent along outer, bearing facial setae; inner plate of maxilliped small, bearing 2 apical spines and 3 facial setae, outer plate of ordinary size, spines small, simple, palp of medium robustness, slightly exceeding outer plate; coxa 1 slightly expanded apically, naked anteriorly, weakly setose ventrally, scarcely scalloped, bearing 2 thin posterior setal-spines, coxae 2-3 rectangular, poorly setose ventrally but with strong subventral setal row medially, scarcely scalloped, each bearing 1 posterior spine, coxae 5-6 with thin posteroventral spines; gnathopod 1 with article 6 about 0.74 times as long as article 5, on gnathopod 2 about the same, gnathopods slightly thin, palm oblique, weakly castellate, medial faces of hands with 7-9 pectinate setae, apical member especially attenuate, anterior face with 3 rows of setae, dactyls bearing 1-2 serrations proximal to main inner tooth; pereopods 1-5 thin, with sharp spines, ratio of articles 4-7 on pereopods 1-2 about 21:18:22:13, dactylar ornaments especially distad; article 2 of pereopod 3 of ordinary stoutness, posteroventral lobe broad but not very deep, article 2 of pereopod 4 pyriform, posteroventral lobe obsolescent but spinose; article 2 of pereopod 5 thin, rectangular, scarcely tapering, posterior margin serrate and posteroventral corner spinose, ratio of articles 4-7 about 24:38:35:18, pereopods 4-5 unusually elongate; pleonal epimera 1-2 with lateral ridge, each with medium sharp tooth, epimeron 3 with small sharp tooth, posterior margins of epimera smooth, setules weak, epimeron 1 with facial row of about 7-8 spines and 1 other ventral spine, epimeron 2 with facial row of 3-5 spines, and 3 spine sets anteroventrally (with 1-2 spines each), epimeron 3 with facial row of 5 spines and 3-4 anteroventral sets of 1-2 spines each (rarely paired); pleonite 1 dorsally smooth, pleonites 2-3 with sharp dorsal tooth and sharp side tooth, pleonite 4 with large, sharp, recumbant dorsal tooth, no lateral; lateral spine present on weak ridge, pleonites 5-6 (fused) with 2 dorsolateral spines on each side; dorsal margin of peduncle on uropod 1 evenly spinose or with weak gap near apex; rami of uropod 3 lacking setae; peduncle with apical pair of spines (unusual); telson flat, not fully cleft, apices of medium width, telsonic taper of high degree terminally, apex with 6-9 sharp cusps, 1 large spine in notch space, lateral margins of each lobe with 5-6 large to small spines, first side spine very close to apex, with lateral serrations occurring apically on lateral telsonic margin, one aberrant specimen with 1 spine position paired; cuticle of posterior body segments smooth or weakly spiculate, but body and coxae covered sparsely with weak setules.



MALE. — With ordinary male characters in antennae such as elongate article 2, ventral brushes of article 1, short article 5 of antenna 2, and setules on article 4 of antenna 2, eyes enlarged, spines of urosome, uropod 3, and telson very short, pereopods 4-5 especially elongate (see Figure 26), article 2 of pereopods 3-5 thinner than in female, coxae and article 2 of pereopods 3-5 much less setose than in female, inner plate of maxilla 1 apparently bearing 1 small medial seta (difficult to observe in two males because of amberization); gnathopods not significantly more elongate than in female.

ALLOPATRIC COMPARISON. — The diagnosis is drawn mainly from the material from Western Australia; material from Victoria, mainly Western Port, differs in small ways but possibly not sufficiently for subspecific distinction; flagellum of female antenna 1 nearly 4 times as long as peduncle; palp of maxilla 1 slightly shorter than outer plate in female but normal in male; ratio of articles 4-7 on pereopods 1-2 about 20:17:18:13, on pereopod 5 about 36:55:42:19, pereopods 4-5 unusually elongate; well-developed females with epimeral formula (s= setule on ventral margin, all other spines considered facial, formula quoted rear to front): epimeron 1: s-2-2-7-1-1, epimeron 2: 4-1-2-1, epimeron 3: 4-2-2-1; pleonite 1 with or without dorsal tooth, generally developing after length of 2.5 mm reached, but in male, tooth developing very late, side tooth always absent in male but often developing after dorsal tooth in female.

ABERRATIONS. — One female, 3.9 mm long, from VicFish 56 has 3 long spines, instead of 1 spine, in the left anteroventral position on pleonites 5-6.

Two well-developed females from VicFish 86 have the ocular lobe almost pointed and have a dorsal tooth on pleonite 1. A male, 4.1 mm long, from VicFish 17 and another specimen from VicFish 96 have have an aberrant telson as shown in Figure 27Tn. Four main setae on the inner plate of maxilla 2 in one male illustrated herein are amberized and appear strap shaped, but apparently they normally are minutely and tightly pectinate or serrate. The secondary medial cusp on the lower lip is occasionally absent on one side.

HOLOTYPE. — WAM, female, 3.4 mm.

TYPE-LOCALITY. — JLB Australia 2, Jervois Bay, Cockburn Sound, Western Australia, on groin 1.6 miles southeast of Woodman Point, 1 meter, algae on rocks, collected by Dr. Barry R. Wilson, 10 June 1968.

RELATIONSHIP. — The cephalocular lobe of this species is intermediate between the two main classes of species in this genus in that it is not perfectly rounded nor is the quadrate cusp (or flange) sharply pointed. This lobe resembles the ocular lobe of P. muriwai J. L. Barnard (in press) from New Zealand, but otherwise P. churinga differs from that species in many characters, especially in the absence of a side tooth on pleonite 4 and in the lack of anterolateral cephalic definition at the base of antenna 2.

If this species is considered to be related to others with a rounded ocular lobe, the absence of side teeth on pleonite 4 suggests a relationship with P. churinga, P. thadalee, and P. dandaloo. This species has close affinities with P thadalee (q. v., for remarks on differences). The aberrant telson of one female of P. churinga, in which one spine position is paired, is a measure of the close relationship, but P. churinga does not have telsonic crests among many other small differences. Both P. thadalee and P. dandaloo differ from P. churinga, as both have no apicolateral serrations and no proximate spine on the telson, and both have a seta on the inner plate of maxilla 1; P. thadalee has multispinose telsonic positions, a short rostrum, and pectinate dactyls on the gnathopods; P. dandaloo has multifid dorsal processes and an enlarged inner plate on the maxilliped.

Though P. churinga is very close to P. marlie, P. linga, and P. moorhousei, its sympatriots, the absence of a cusp on the ocular lobe places P. churinga in the species group containing P. fissicauda, P. nana, P. sexdentata, and P. dandaloo, which, like P. marlie, have no side tooth on pleonite 4. Paradexamine churinga differs from P. fissicauda in the slightly stouter article 2 of pereopod 5, the broader telsonic apices, the weak inner plate of the maxilliped, the thinner mandibular lobes of the lower lip, the absence of teeth anterior to pleonite 2, the recumbant dorsal tooth of pleonite 4, and the attenuate rostrum.

By lacking side teeth on pleonite 2, P. sexdentata has a tooth formula weakly similar to P. churinga, but P. sexdentata has a dorsal tooth on pleonite 1, and the side teeth of pleonite 3 are sharp. Paradexamine fissicauda has a simple telsonic apex with 1 main notch and spine.

Paradexamine nana apparently has the same tooth formula as P. churinga, but presumably the side teeth of pleonite 3 are sharp; very little else is known of P. nana from the Falkland Islands.

In the group of species with a fully developed, sharp cephocular cusp, P churinga appears similar to P. marlie, P. moorhousei, P. linga, P. houtete, and P. pacifica. The latter two species have a combination of 2 setae on the inner plate of maxilla 1, a large inner plate on the maxilliped, and no apicolateral telsonic serrations. Paradexamine linga and P. moorhousei have weak to vestigial mandibular spines, pectinate dactyls on the gnathopods, and large inner plates on the maxillipeds. Paradexamine marlie has no mandibular spines, a seta on the inner plate of maxilla 1, no apicolateral serrations on the telson, and pectinate gnathopodal dactyls.

The following characters have been relied on to identify this species in the enormous VicFish collections (because each specimen has not been dissected, there may be cryptosiblings overlooked): lateral cephalic lobe, pleonite 4, rostrum.

MATERIAL. — JLB Australia 2 (8); VicFish 1-105, 21 samples (20); Shepherd 30 (1).

DISTRIBUTION. — Warm-temperate Australia, sublittoral, bays.