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Comprehensive Description

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General Description

The integument thin is, shining, and is minutely punctate. The rostrum is almost straight, and is imperceptibly elevated above horizontal in the distal half, with the sharply pointed tip usually reaching the proximal level of the second peduncular article of the antennule, but sometimes to the proximal part of the third peduncular article. The dorsal margin is raised into a thin serrate crest that contains 12-17 teeth, the strongest in the central sector of the row, with about one-half the length of crest continued onto the carapace. The ventral margin is less prominent, and is armed with 1 or no subterminal teeth. Sample tooth formulas from specimens are 11/1, 12/0, 14/1, and 17/1. The lateral carina are broadened proximally and are confluent with the orbital margin. The carapace has a distinct buttressed acuminate antennal spine. The pterygostomian spine is acuminate and prominent. There is a prominent anterior antennal carina that curves posteroventrally to intersect obliquely with the carina that extends from the pterygostomial spine at about the midlength of the carapace, and an associated groove continues indistinctly posteriad.

The abdomen of both males and females is broadly arched dorsally, and gradually tapering distally. The narrowest part of the sixth somite is less than one-half (0.44) the width of the first somite. The pleura of the 3 anterior somites are broadly rounded, whilst that of the fourth somite is drawn posterolaterally into an acuminate spine that is flanked dorsally by 0-3 spines, which are much smaller and more slender. The posterolateral corner of the fifth pleuron varies from strongly acuminate to nearly rectangular and is flanked dorsally by 2-5 spines that are analogous to those on somite 4. The sixth somite has a middorsal length about 1.8 times that of the fifth, and there is a broad-based midlateral spine that overlaps the base of the telson, and a smaller acute posterolateral spine. The fourth and fifth somites each have a strong, posteriorly directed spine on the sternite. The telson is an elongate subrectangular shape, with a length of about 2.8 times the anterior width, 5.2 times the posterior width, and about 1.7 times the length of the sixth somite (not including the posterior spines). The telson is armed with 5-8 dorsolateral spines that are nearly uniform in size, but occasionally unequal in number on either side. The posterior margin is convex, and is armed with 2 principal spines at each corner. On the distal margin between the spines there are 8-12 feathered strong setae.

The eyes have an imperfectly developed cornea that is unfaceted though diffusely pigmented in the adults. Smaller individuals have an internal facet-like pattern. The cornea is ovate in outline, though fused to each other mesially. Each has an upturned spine on the anterodorsal surface.

The antennular peduncle reaches beyond the end of the antennal scale. The basal article measures 1.3 times the length of second and about 2.2 times the length of the third (all measured on the dorsal margin). The stylocerite is well separated from the peduncle, and tapers to a slender elongate tip that variably reaches as far as the midlength of the second article. The basal article has a distodorsal margin that is exceeded by the rostral tip. The distodorsal margin extends into a strong lateral spine that reaches a level equal to that of the stylocerite, and is closely appressed to the second article. There is a much smaller distomesial spine that is slightly divergent. The second article is shorter tah the first, and has a stronger mesiodistal spine. The dorsolateral flagellum is about twice the length of the carapace, and is thickened in the basal half. The ventromesial flagellum is somewhat shorter than the dorsolateral falgellum.

The antennal scale is about twice as long as it is wide, and has a strong distolateral tooth that falls short of the broadly rounded distal margin of the blade. The basal article has a small distal spine ventrally. The flagellum slightly exceeds the length of body.

The mandibles are similar, having a 2-segmented palp, a broad incisor process, and being armed with 7 marginal teeth. There is also a simple slender molar process that is divergent and has a minutely setose narrowly rounded tip.

The first maxilla has a proximal endite, which is asymmetrically oval-triangular in shape with a distal margin that bears about 25 long setae. The distal endite has a narrowed base but is broadened distally, and is armed with many short spines on the mesial margin. In addition there are scattered longer spinules submarginally and marginally beyond either end of the spine row. The palp is scarcely bifurcated, with a long distal spine on the obsolescent proximomesial branch, while the distal branch has a shorter adjacent submarginal spine and some tangled setae.

The second maxilla has a proximal endite that is represented by 2 similar lobes. The distal endite is subtriangular, but is expanded mesiodistally. The endite is paralleled laterally by a narrow and somewhat twisted palp. The scaphognathite has a rectangulo-ovate anterior lobe, which is fringed with uniformly long, silky setae on the anterior and mesial borders. There are uniformly shorter setae along the entire lateral margin. The posterior lobe is narrow and acuminate. It is fringed on the blunt tip and the adjacent mesial margin by strong setae that are strikingly long and tangled. These setae are preceded proximally by shorter setae, which are similar to those on the lateral margin.

The first maxilliped has an irregularly fusiform endite, and a short palp that is concealed and much exceeded in length and size by a leaf-like exopod. The epipod is obscurely bilobed. An indistinct mesial lobule is present on the exopod, possibly representing the incipient lash.

The second maxilliped is somewhat pediform but flattened, with the mesial margin of the articles bearing long, feathered setae. The mesial surface of the terminal article is densely setose, and the exopod barely exceeding the leaf-like epipod.

The third maxilliped is slender, and 5-segmented, reaching beyond the antennular peduncle. The terminal article is trigonal in cross section, and is tapered distally. It bears 3 spines, with transverse tracts of dense setae along the mesial surface. There is a similar tract of setae on the carpus and another less conspicuous group on the merus-ischium. The latter has a stout distolateral spine at the articulation with the carpus. The exopod is much reduced, and subtriangular is shape, but is without a lash.

The first pereopods are chelate, subequal and sexually dimorphic (at least in fully mature individuals). The fingers are curved ventrally and slightly laterad. The dactyl is more slender than the fixed finger, and the tips varying slightly in their relative length. The mesial surface of each finger is convex, while the lateral surface is concave. The prehensile surfaces are uniformly offset, and close without a gape. Each prehensile surface is armed with a row of almost uniform teeth that are so closely set as to be almost contiguous. There is a line of sensory hairs mesial to the cutting edges, and the acute tip of the dactyl is slightly spooned by elongate teeth that are slanted distad and curve around the external edge. The palm is inflated in the holotype male, with a length 1.4 times the greatest height and is longer than the fingers. The palm is relatively shorter in the allotype female and the other individuals examined, measuring 0.3 times the length of the fingers. The carpus is shorter than the palm in the holotype, but is longer than the palm in the other specimens examined. The carpus bears an oblique ventral crest that ends in a strong distolateral spine, which is flanked mesially by a patch of setae on a polygonal raised area. There is a notch above the spine that is smoothly concave, and an opposing low ridge that ends in a small rounded spine on the heel of the palm. The shallowly concave anteromesial margin of the carpus leads dorsally to 2 low rounded lobes. The merus is somewhat swollen in the distal half, and is distinct from the ischium but fused to it. Neither the merus nor ischium is armed.

The second pereopod is shorter and more slender than the first, reaching to between the midlength and the end of the antennal peduncle. The fingers are slightly longer than the palm, and are similar in size and shape, with the opposed edges without a gape. Each opposed edge is pectinate with a single row of teeth in the distal half that are directed obliqueiy distad, but is spineless proximally. The row of teeth increase slightly in size towards the end, where a noticeably stronger tooth crosses the opposite member when the fingers are closed. The carpus is slender, and is about 1.2 times longer than the chela. The merus and ischium are unarmed.

The third to fifth pereopods are similar in length and structure. The third pereopod reaches beyond the antennal scale by about 0.3 times the length of the propodus. Each short dactyl is armed with about 6 corneous spines on the flexor surface, grading in size from small proximally to the longest and strongest distally. The carpus of each pereopod has a distodorsal extension that projects as a stop along the proximal part of the propodal extensor surface. The third leg is stronger, at least in the merus-ischium, than the fourth and fifth. The merus of third and fourth legs has a ventral spine at one- and two-thirds of the length. The distal spine is the strongest. The merus of the fifth pereopod is without spines. The ischium of the third pereopod has 2 spines in line with those on the merus, whilst the ischium of the fourth and fifth legs is spineless.

The pleopods are well developed. Pair 1 has endopods about half the length of the exopods in both sexes. The endopod of the male has an asymmetrical mesial extension, while that of the female tapers to an acute tip. Pair 2 has an appendix masculina of the male that bears a distal cluster of about 9 strong straight spinules, which extend beyond the level of the simple slender appendix interna.

The uropod has rami that are subequal in length, and which slightly exceed the distal end of the telson. The lateral ramus has a movable spine mesial to a smaller distolateral tooth. The diaeresis is sinuous.

(Williams, 1988).


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