Paradexamine frinsdorfi Sheard 1938

Paradexamine frinsdorfi Sheard, 1938:182–185, figs. 6T, 8A–L, 9

DESCRIPTION (of medium female, about 4.5-5.0 mm). — Lateral cephalic lobe rounded anteriorly and very tumid and thick side to side, head well defined at base of antenna 2, rostrum medium blunt; article I of antenna 1 with ventral spines thick and arranged in 1 group of 2 (with pair of proximal setae), article 2 about 1.3 times as long as article 1, apically simple and with 1 set of strong spines ventrally, flagellum about 0.9 times as long as peduncle; flagellum of antenna 2 only 0.6 times as long as peduncle, multiarticulate; mandibles bearing 2 large spines on right, 2 on left, molar strongly ridged, ragged seta each side, regular setae both sides, slightly longer on right, accessory bulge small, sharp, outer lobe of lower lip bearing 2-4 large cones; mandibular lobes straight, blunt; palp of maxilla 1 of medium width, not reaching apex of outer plate, bearing apical and medial setae, no apical cone, inner plate very large, naked, nearly reaching apex of outer plate; inner plate of maxilla 2 narrower than outer, both appressed, inner with apex evenly tapering, outer not curved, inner reaching 90 percent along outer; inner plate of maxilliped attenuate, large, long, bearing 2-3 long apical spinules, and 3 short laterals, outer plate of ordinary size, spines of medium size, slightly bi-trifid, palp of medium robustness, slightly exceeding outer plate, article 4 especially elongate; coxa 1 slightly tapering apically, with weak anterior acclivity, strongly setose anteriorly and ventrally, well scalloped, coxa 2 slightly rounded below, coxa 3 rectangular and slightly extended posteroventrally, coxa 4 also sharply but weakly extended, all moderately setose, coxae 2-3 with posterior spine, coxae 5-6 moderately setose-spinose ventrally; gnathopod 1 with article 6 about 0.74 times as long as article 5, on gnathopod 2 about the same (0.71), gnathopods of ordinary stoutness, hands widely expanded apically and palms oblique, hands thus subtriangular, palms weakly serrate, medial faces of hands with oblique setal row composed of 1-2 simple setae and 2-3 stout pectinate setae, anterior setal row on face single, dactyls smooth proximal to main inner tooth, latter highly distad; pereopods 1-2 slightly stout, with blunt spines, ratio of articles 4-7 about 16:15:22:12, dactylar ornaments moderately distad; article 2 of pereopod 3 of ordinary stoutness, posteroventral lobe deep and narrow, article 2 of pereopod 4 pyriform, posteroventral lobe obsolescent but spinose; article 2 of pereopod 5 broadly quadropyriform, expansion mainly proximal, posterior margin deeply serrate and sparsely spinose, ratio of articles 4-7 about 19:40:25:13, pereopods 3-5 otherwise thin distad of article 2; pleonal epimera 1-2 with lateral ridge, each with small-medium sharp tooth, epimeron 3 with medium sharp tooth, posterior margins of epimera very weakly and irregularly serrocastellate, epimeron 1 ventrally with about 5 setules near middle, epimeron 2 with 2 spinules in tandem, epimeron 3 with about 5 ventral spinules; pereonite 7 with small dorsal tooth and side tooth and setae (occasionally side teeth absent), pleonites 1-4 with sharp dorsal tooth and sharp side tooth, dorsal tooth of pleonite 3 slightly anteriad and decumbant, dorsal tooth of pleonite 4 projecting nearly vertically and with weak anterior shoulder, lateral ridge of pleonite 4 with spine, pleonites 5-6 (fused) with 2 dorsolateral spines each side; dorsal margin of peduncle on uropod 1 evenly spinose; inner rami of uropod 3 with short setae proximally; telson uncrested, apices tapered, of medium width, each bearing small spine in main notch and with medial protrusion blunt, lateral margin of each lobe with 4-5 medium-to-long spines in tandem; cuticle on posterior body segments heavily spiculate.



MALE (terminal, 4:1-5.2 mm). — Ocular lobe not evenly rounded but with weakly quadrate protrusion (like P. churinga), rostrum thick and blunt, eyes very large, antennae elongate and normally setulose, article 5 of antenna 2 not especially shortened relative to known males of other species, article 3 of antenna 2 with mediodorsal tooth; each lobe of lower lip bearing 2 large cones; inner plate of maxilla 2 bearing distinctly truncate apex; inner plate of maxilliped elongate, slightly attenuate, bearing 4 long apical spines and 2 laterals (or 3 apical and 3 laterals, depending on interpretation); spines on outer plate bifid; coxa 1 slightly like that in female, with very weak indication of anterior protrusion, coxa 2 lacking posterior spine, coxa 3 with very short ventral setae and 1 thick posterior spine; gnathopod 1 of ordinary kind in genus, thin and unlike that of female, hand scarcely expanded, article 5 elongate, article 6 only 0.77 times as long as article 5; gnathopod 2 also with article 5 very elongate, article 6 only 0.73 times as long as 5, but hand slightly expanded as in female, palms of gnathopods more oblique than in female; pereopods 1-2 much like those of female, dactyls each bearing 4 extra setae in tandem on outer margin; pereopod 3 like that of female; article 2 of pereopod 4, however, becoming more like pereopod 5, more quadrate and with posteroventral margin nearly horizontal; lobe on article 2 of pereopod 5 weak, article 5 very elongate; ratio of articles 4-7 on pereopod 5 about 28:54:35:18; crests on telson weak; spines on urosome small, dorsal teeth otherwise like those of female, apparently no lag in development of anterior teeth; urosomite 1 lacking anteroventral setae; uropod 3 unknown; epimeron 1 with 9-14 ventral setae of various sizes, epimeron 2 with 3 ventral spines, 1 facial seta, epimeron 3 with 7 ventral spines, 1 facial spine, 1 anteroventral seta; basolateral face of peduncle on uropod 1 with 3 spines.

TRANSFORMING MALE (Shepherd 15, 6.4 mm). — Scarcely different from female, eyes slightly enlarged, article 1 of antenna 2 with medium lobe, cones on lower lip 4 and 3 on either side, pereonite 6 lacking tooth, 3 teeth of pereonite 7 weak; telson and maxillipeds normal; gnathopod 1 with 2 dorsomedial facial rows of setae of 6 and 1 each. This specimen is possibly a monster intersex or a sexually retarded giant.

DEVELOPMENT AND VARIABLES. — The 7.5 mm female from Shepherd 16 differs from 4-5 mm females in the presence of 2 short setae in tandem on the outer curved margin of the dactyls of pereopods 1-2, 4-5, and 3 setae on pereopod 3, in the presence of 2 well-developed sets of spines on each of articles 1 and 2 ot antenna 1, in the weak development of cusps on the medial protrusion of the telson, in the presence of 6 setae on the oblique row of the hand of gnathopod 1 and of 6 setae in the anterior row, in the stronger seto-spinosity of the epimera, epimeron 1 with 8 setae and 1 spine ventrally, epimeron 2 with 3 ventral and 1 facial spinules, epimeron 3 with 8 ventral and no facial spinules; the outer lobes of the lower lip are similar in having 2 cones on one side and 4 on the other.

The first gerontic female of WAM Bunbury, 12.1 mm long, has the following characters differing from the 7.5 mm and 4.5 mm stages: brood plates slightly vestigial and lacking setae, article 2 of antenna 1 about 1.5 times as long as article 1, flagellum 1.7 times as long as peduncle, flagellum of antenna 2 about 0.7 times as long as peduncle, article 1 of antenna 2 with extended lobe; gland cone vestigial; mandible with 3 spines on left side, outer lobes of lower lip with 9-11 cones on accessory lobe, inner plate of maxilla 2 about 80 percent as long as outer: inner plate of maxilliped short, broad, obliquely truncate, with about 4 very small spines; acclivity of coxa 1 strong, setae weak, sparse, ventral scallops weak, article 6 of gnathopod 1 about 0.83 times as long as article 5, hands highly triangular; pereopods 1-2 slightly stouter, ratio of articles 4-7 about 24:25:33:20, lobe on article 2 of pereopod 3 broad, article 2 of pereopod 5 broadly pyriform, resembling pereopod 4, articles 4-7 with length ratio of 24:40:21:14; epimeron 1 with 2 ventral spinules, 9 setules in middle, 3 setules posteroventrally, epimeron 2 with 3 ventral spinules, 1 facial; pereonite 5 with dorsal setae, pereonite 6 with dorsal tooth and side setae, pereonite 7 with 3 teeth like those on pleonites, shoulder of dorsal tooth on pleonite 4 well developed, medial protrusion of telsonic apex with 3 sharp cusps; cuticle scaliform.

The second gerontic female of WAM Bunbury, 11.3 mm, differs radically from the 12.1 mm female in the reduction or loss of ventral spines on article 2 of antenna 1, their reduction or loss on antenna 1 (right and left sides vary), in the lack of a lobe on article 1 of antenna 2, in the medium-sized inner plate of the maxilliped showing some rudiments of truncation but bearing I long apical spine and several lateral and medial spines, in the long setae of the anterior coxae, the development of a second dorsal row of setae on the hand faces of the gnathopods, in the far better developed facial spines of article 2 on pereopod 3, more like the 4.5 mm stage than the 12.1 mm female, in the broad article 2 of pereopod 5 bearing a horizontal ventral margin, the elongate article 5 of pereopod 5 (more like youthful stages), in the subcircular article 2 of pereopod 5, the presence of 2 spines each on the posterior margins of coxae 2-3, the absence of dorsal ornamentation on pleonites 5 and 6, the highly enlarged dorsal crest, tooth, and shoulder of pleonite 4, and, finally, in the lateral pairing of spines on the telson and the extremely widened and spinose apices.

At first it was believed that the two Bunbury specimens represented different species, but an intergrading stage was found in a 7.2 mm female from Shepherd 13, with an intermediate telsonic stage. Apparently aberrations occur in giant specimens of this species, but they are not synchronous nor consistent: in some specimens the telson remaining normal, in others having the apices broadened and spinose; in some specimens having only 1 anterior face row of setae on the hands of the gnathopods, in others having an extra row; in some specimens article 2 of pereopod 5 developing normally in breadth and spinosity, whereas in others becoming pyriform like pereopod 4, with the distal portion strongly narrowed; in some specimens article 5 of pereopod 5 not becoming elongate or becoming shortened in senility; and, finally, in some specimens having the facial spinosity of article 2 on pereopod 3 reduced. The specimen from Shepherd 13 and the 11.3 mm specimen from Bunbury show the stages between the normal inner plates of the maxilliped and the aberrant terminal condition of the 12.1 mm specimen from Bunbury, in which the plate becomes shorter, broader, loses the attenuation, and loses the long apical spines or has them reduced in length.

The odd gland cone of the giant specimens from Bunbury, Western Australia, has not been found in specimens from South Australia, though none from South Australia is as large as those from the west.

The female from Shepherd 13 with intermediate telson has no tooth on pereonite 6, the cones on the lower lip are 6 and 5 on either lobe, the gland cone is of medium size, and article 2 of antenna 1 has only 1 short ventral spine. The telson has 2 terminal spines, and one spine position on one lateral margin has 2 spines.

Specimens as small as 3.0 mm from Western Port, Victoria (e.g., VicFish 62) have extra setae on the outer margins of the pereopodal dactyls, 1 seta on pereopods 1-2, and 2 setae on pereopods 3-5. The left mandible has 3 spines, the medial edge of the palp of maxilla 1 has only 1 seta, the lower lip has 3 cones on each lobe, and the gnathopods have only 3 setae in the oblique row.

A male, 4.6 mm, from VicFish 102, has a sharp dorsal tooth on pereonite 7, but the dorsal tooth on pleonites 1-2 is obsolescent and the side teeth of pleonite 1 are very small.

One aberrant male, 5.1 mm from Vic Fish 13, has a poorly spinose epimeron 3 bearing a grossly enlarged and distorted posteroventral tooth (Figure 52xE3).

REMARKS (on the original description). — Sheard pointed out the heavily folded gills of this species, seen especially well in the specimens nearly 12.0 mm long but clearly apparent in those of 7.5 mm length. Sheard’s citation of figure “7J” is erroneous, as he means “8J” for the brood lamella. His figure 8 is cited as showing the type male, but the pereopods have vestigial brood lamellae (he does mention the problem of intersexes). He shows the long inner plate of the maxilliped and he describes this plate as small, but the spines are unclear. The lower lip lacks any cones in his figure and description; the outer plate of maxilla 2 is more flabellate than in material at hand. He has the form with narrow telsonic apices, but his gnathopods are of the form seen only in my specimens nearly 12.0 mm long, whereas his specimens are 6-8 mm long. He shows 4 (or 3, depending on interpretation) anterior setal rows on the gnathopodal hand faces. The rostrum is acute only from dorsal view. Since I have one specimen with more than one anterior row of setae on the gnathopodal hands, this point can be dismissed. The other discrepancies are probably interpretive; apparently Sheard overlooked the cones on the lower lip of other species, such as P. pacifica, though he used them elsewhere taxonomically.

RELATIONSHIP. — This species differs from P. flindersi, P. ronggi, and P. otichi especially in the triangular hands of the gnathopods (the three latter species have transverse palms). Paradexamine windarra and P. narluke have a posteroventral lobe on article 2 of pereopod 5 plus normal gnathopods or those nearly like P. flindersi. Paradexamine goomai comes close to P. frìnsdorfi in telson, coxae, and pereopod 5, but the extension of coxa 3 is much more exaggerated (in a much smaller range of body length); otherwise, one might visualize P. goomai, a small species, as simply representing juveniles of P. frinsdorfi, but it lacks dorsal teeth anterior to pleonite 2.

Neozelanican P. muriwai also has some elements that suggest it is a normal growth stage of P. frinsdorfi, but, because it is fairly unusual in having 2 apical spines on each lobe of the telson and a rectoquadrate article 2 of pereopod 5, it resembles more nearly the aberrant 11.3 mm specimen of P. frinsdorfi.

Males of P. frinsdorfi differ from females in several characters typical of P. lanacoura: the epimera on small males, 4.2-5.0 mm, have setae nearly as dense as in P. lanacoura, but in males larger than about 5.5 mm the epimera become serrulate as in the normal adult female and the setae are fewer or not so prominent; the telsonic apices have the widened medial truncation, but it is slightly serrate (2-3 serrations) and thus does not fully conform to P. lanacoura females. Small males also have a distinct posteroventral lobe on article 2 of pereopod 5 like P. lanacoura, but males exceeding 5.5 mm in length have pereopod 5 much like that of females.

MATERIAL. — Shepherd 6 (1), 13 (1), 14 (1), 15 (1), 16 (1), 17 (1), 23 (2), 25 (1), 26 (1), 30 (1), 52 (1); VicFish 1-105, 11 samples (25); WAM, Bunbury (2).

DISTRIBUTION. — Warm-temperate Australia, sublittoral.