Paradexamine lanacoura J. L. Barnard 1972

Paradexamine lanacoura

DESCRIPTION (of female). — Lateral cephalic lobe rounded, protruding, thick side to side, head with distinct anteroventral definition, rostrum extremely thin and attenuate; article 1 of antenna 1 with 1 set of ventral spine(s), 1 set of setae, strong ventrodistal tooth with setae, article 2 about 1.5 times as long as article 1, apically simple but with strong spine set ventroproximally, flagellimi about equal in length to peduncle; flagellum of antenna 2 only 3-4 articulate, not as long as article 4 of peduncle (see “Aberrations”); mandibles with large spines, 2 on right, 3 on left, molar heavily triturative, both sides with ragged seta and ordinary setae, accessory bulges rounded, bearing thick sparse setules, these doubled setules also on upper smooth portion of molar and several very thin setules mixed among spines of spine row; outer lobe of lower lip with 3-4 medium-to-long cones, mandibular projections thick and blunt; palp of maxilla 1 of ordinary breadth, much shorter than outer plate, bearing 2 apical setae, 2 medial setae, no apical cones, inner plate large, naked; inner plate of maxilla 2 narrower than outer, reaching only 67 percent along outer, latter with curved outer margin, plates not appressed, inner with no distinct apex and several medial setae; inner plates of maxilliped very small, each bearing 1 small spinule, palp slightly exceeding outer plate, latter ordinary, with simple medium spines, palp article 4 elongate; coxa 1 narrow, tapering, anteriorly and ventrally setose and weakly serrate, coxa 2 also tapering, bearing 2 long and large spines posteriorly and attached medially, ventral setae long, coxa 3 slightly prolonged, scarcely serrate, setae of medium length, no posterior spine but 1 weak posterior seta present, coxa 4 with long setae, coxae 5-6 with numerous thin spines and setae; gnathopods stout, gnathopod 1 with article 6 about 1.25 times as long as article 5, about 1.12 times on gnathopod 2, article 5 broad, expanding apically, palm slightly oblique, extremely finely serrate, dactyl with apical ornaments highly distad, not pectinate proximal to main inner tooth, oblique setal row on medial face of hand with 5 thin setae, distal 1-2 setae weakly pectinate, 3 and 2 anterior setal rows on faces of gnathopods 1 and 2 respectively; pereopods 1-5 of regular stoutness, with numerous blunt spines, ratio of articles 4-7 on pereopods 1-2 about 17:18:21:14; article 2 of pereopod 3 moderately narrow, with regular posteroventral lobe; article 2 of pereopod 4 pyriform, posteroventral lobe obsolete, bearing spine, posterior margin setose; article 2 of pereopod 5 quadropyriform, posterior margin serrate, posteroventral margin with weak, spinose lobe, article 5 slightly elongate, ratio of articles 4-7 about 17:37:21:17; pleonal epimera 1-2 with weak lateral ridge, epimeron 1 with small, sharp posteroventral tooth, epimera 2-3 with medium tooth, epimera smooth posteriorly but with numerous long setae, irregularly or very regularly spaced, epimeron 1 with 2-3 ventral spines and 5-6 setae, epimeron 2 with 5-6 ventral spines and 4-5 anteroventral setae, epimeron 3 with 8-9 ventral spines and 2-4 anteroventral setae, anteroventral margin of urosomite 1 with 2-3 setae; pereonite 7 with sharp dorsal tooth; pleonites 1-4 each with sharp dorsal and sharp side tooth, pleonite 4 with spine on side ridge, pleonites 5-6 (fused) with 2 dorsolateral spines on each side; dorsal margin on peduncle of uropod 1 evenly spinose; inner ramus of uropod 3 with setae; telson with high longitudinal crests, apices broad, nearly truncate or weakly serrate, each bearing small apicolateral spine, sides of each lobe with 4-6 thin spines and 3 setae; cuticle of posterodorsal body segments scarcely spiculate but bearing large setules.

MALE (5.2 mm, VicFish 43, probably subterminal). — Eye enormously enlarged, reaching dorsally to level of dorsal edge of antenna 1; article 1 of antenna 1 bearing distoventral lobe like that of female, article 2 lacking ventral spines, setulation of antennae typical, article 4 of antenna 2 elongate but with lateral spine sets, 4 spines at mark 35, 1 spine at mark 60, article 4 slightly elongate and article 5 also elongate, ratio of 5 to 4 about 47:100, article 5 with slight apicoventral tooth; medial setae on coxae 1-4 fewer and longer than in female; medial oblique row on hands of gnathopods 1-2 composed of 4-5 setae, varying (right-left) from 2-4 pectinate and 0-3 simple on gnathopod 1, 4 pectinate and 2 simple on gnathopod 2, anterior hand setae on face of gnathopod 1 in sets from distal to proximal of 5-4-5 setae each, on gnathopod 2 of 5-3-2; article 5 of gnathopods slightly elongate compared with female; epimeron 1 with posteroventral tooth obsolescent; following characters unknown: distal articles of pereopods 4-7, telson and uropod 3 (all missing); following characters like those of female: rostrum, all mouthparts, pereopods, uropods 1-2, epimera 2-3, dorsal pleonal teeth, and posterior armaments of coxae 1-4.

TRANSFORMING MALE (VicFish 78, 5.0 mm.).—Apparently males do not necessarily transform from female-like morphology as early as 4.0 mm; this specimen combines characters of the female and terminal male to demonstrate the proper identification of the terminal male. The following characters are like those of the female: rostrum, epimera, inner plate of maxilliped (but with 2 spines each), spines on outer plate of maxilliped (but scarcely bifid), mandibular setules, setose molars, lower lip, 2 spines of coxa 2, gnathopods, shape of coxa 1, lobe on pereopod 5, and strong terminal anteroventral lobe on article 1 of antenna 1, despite setulation normal to male. These characters are like the terminal male: ventral setulation of article 1 on antenna 1 but only basally on article 2, setulation fully developed dorsally on articles 4-5 of antenna 2; pereopod 4 fully developed; tooth on article 3 of antenna 2 of medium size, shaped like a hump basally; urosomal spines small.

Another transforming male (VicFish 35, 4.3 mm) is generally like the female but bears penial processes, antenna 2 with 9-articulate flagellum, and inner plates of maxillipeds slightly enlarged.

JUVENILES (2.8-3.0 mm.) — Female-like with following characters adequately similar to adult female for purposes of identification: antenna 2 (flagellum 3-4 articulate), article 1 of antenna 1, rostrum, bulging ocular lobe, mandibles, lower lip, maxilliped, coxae 1-2, pereopods 4-5, epimeral setae (posterior edges), and the tooth formula of the pleon, with dorsal teeth on pleonites 1-2 relatively larger than in most adult females and side teeth of pleonite 4 difficult to see unless pleonites 5-6 extirpated; telsonic crests large, inner ramus of uropod 3 with inner margin bearing setae and spines in formula PSSPPP proximal to distal (P=spine, S=seta); ventral margin of epimeron 1 with 1 spine, 1 seta, 1 setule; epimeron 2 with 2 spines, no facials; epimeron 3 with 3 ventral spines; lateral base of peduncle on uropod 1 with 2 spines; gnathopods like adult but oblique facial row with only 3 simple setae, anterodorsal facial setae of gnathopod 1: 2, 1, on gnathopod 2: 1 only; palp of maxilla 1 with only 2 apical setae, no medials, and 1 short cone; maxilla 2 like adult but outer margin of outer plate with 4 setae, apex with 7, inner margin of inner plate with 3 setae, apex with 3. Generally in younger specimens article 2 of pereopod 5 has the posteroventral margin truncate like P. ronggi, but gnathopods remain like P. lanacoura.

ABERRATIONS. — One specimen of VicFish 107 lacks setae on epimeron 3 on both sides of the animal but bears normal setae on epimeron 2; the dorsal segmental teeth are very small. One female (5.4 mm, VicFish 27) has the flagellum of antenna 2 about 11-articulate and 1.4 times as long as article 4 of the peduncle.

NOTES. — The majority of specimens of this species in the VicFish collections from Western Port have perfectly transverse palms on the gnathopods. On occasional specimens one can turn articles 2 and 3 of antenna 1 in such a way as to create a point on article 2 like that described by Stebbing (1910a) for P. flindersi.

HOLOTYPE. — NMV, female, 5.6 mm.

TYPE-LOCALITY. — VicFish 69, Western Port, Victoria, Station 22N-2-1 and 2.

RELATIONSHIP.—Paradexamine lanacoura appears to have the fewest of differences from P. windarra, differing from that species in the evenness of spination on the peduncle of uropod 1, in the short flagellum of antenna 2, in the more acute rostrum, in the unserrate epimera, in the absence of seta on the inner plate of maxilla 1, and in the smoother apices of the telson. The two species are very similar in coxae 1-2 spination, pereopods 4-5, mandibles, gnathopods, maxillae, and maxillipeds.

The female of Paradexamine lanacoura differs from P. ronggi in the lobation of pereopod 5, the spines of coxa 2, the small inner plate of the maxilliped, the broader hands of the gnathopods with more oblique palms, the unserrate epimera, the better trituration and setosity of mandibular molars, the better development of spines on the left mandible (but only 3 spines instead of 4), and the broader apices of the telson. Paradexamine lanacoura also differs from females of P. ronggi in pereopod 5, epimera, molars, and telson, but no male of P. ronggi is known.

A close relationship occurs with P. flindersi, an open-sea sympatriot of P. lanacoura, but more differences occur than with P. ronggi and P. windarra. Paradexamine lanacoura differs from P. flindersi in the lobe of pereopod 5, the 3-4 articulate flagellum of antenna 2 (these articles apparently coalesced in P. flindersi), the absence of a tooth on article 2 of antenna 1, the small inner plate of the maxilliped, the shape of coxa 1 bearing anterior setae, probably the shape and spination of coxa 2 (not fully known in P. flindersi), the unserrate epimera, the more apically expanded hands of the gnathopods with slightly oblique palms, and the broad apices of the telson. The male fits these differences in pereopod 5, coxa 1, and the telson and, moreover, has thin gnathopods with very oblique palms.

Paradexamine lanacoura differs from P. goomai in the broad smooth telsonic apices, the small inner plate of the maxilliped, the normal coxa 3, lobation on pereopod 5, the short flagellum of antenna 2, the tooth on article 1 of antenna 1, the short inner plate of maxilla 2, the narrow coxa 4, and the poorly serrate coxae. The male of P. lanacoura fits the differences stated in telson, coxa 3, pereopod 5, coxa 4, and coxal serrations.

Paradexamine lanacoura differs from P. frinsdorfi in the lack of a protrusion on coxa 1, the lobation of pereopod 5, the broad telsonic apices, the small inner plate of the maxilliped, the short flagellum of antenna 2, the unserrate epimera (apparently only some specimens of P. frinsdorfi have serrations), the more than one set of anterior setae on the faces of the gnathopodal hands, the sharp rostrum, the tooth on article 1 of antenna 1, the short inner plate of maxilla 2, the double spines of coxa 2, and the lack of spines on coxa 3. The male of P. lanacoura fits the differences in coxa 1 only weakly, pereopod 5 weakly, but fits strongly on telson, epimeral serrations, and gnathopodal hand setal formulae plus the thin gnathopods, and especially gnathopod 1.

Finally, P. lanacoura differs from P. otichi in many strong characters such as the enlarged spines of the mandibles, the triturative molar with setae, the large cones on the lower lip, the less rectangular inner plate of maxilla 2, the tapering coxa 1, the unextended coxa 3, the smaller inner plate of the maxilliped, the spines of coxa 2, the lobe on pereopod 5, and the broad apices of the telson.

The elongate article 4 of the maxillipedal palp is a character also found in the first five species mentioned above, but the rostrum of the female appears to be distinct from that of those species.

MATERIAL. — VicFish 1-105, 38 samples (252).

DISTRIBUTION. — Western Port, Victoria.