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Comprehensive Description

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Description

"On March 19th, 1929, I had the honour to receive a letter, dated February 9th, from Professor R. Speight, of the Canterbury Museum, Christchurch, New Zealand, in which he informed me that he would send me for identification a species of shrimp, specimens of which had been presented to that museum. These shrimps were taken from the stomach of a groper (Polyprion prognathus), captured in two fathoms of water off Kaikoura, on the east coast of the South Island of New Zealand, a well-known fishing ground with lines, where the deep water comes to within a short distance of the shore. Four full-grown speci­mens, one of which is provided with eggs, were received, but unfortunately all are more or less damaged and broken.

 

After a thorough examination they proved to belong to a new species of the genus Hoplophorus H. M.-Edw., distinguished probably from all the known species of this genus by the outer margin of the antennal scale being smooth and unarmed—I say probably, because this margin is perhaps also smooth in H. spinicauda A. M.-Edw., a species collected by the ‘Travailleur,' July 1882, at a depth of 636 m., according to the figure in the ‘Recueil de Figures de Crustacés nouveaux ou peu connus,' published by A. Milne-Edwards in 1883. H. spinicauda, however, of which unfortunately a description does not exist, differs at first sight from H. novæ-zeelandiæ by the termination of the 2nd segment of the abdomen in a spine.

 

In no one of the four specimens is the rostrum complete, so that the exact length could not be indicated with certainty. In one specimen the carapace, measured in the mid-line from the posterior border to the orbital margin, proves to be 17 mm. long, the still existing part of the rostrum 28 mm.; the rostrum of this species is therefore probably twice as long as the carapace. This specimen is broken and much damaged. In another, a male, which is the best preserved and therefore the specimen which will be described, the carapace is also 17 mm. long, the abdomen 44 mm., so that the whole length may be estimated at 95 mm. Of the ova-bearing specimen, of which the carapace is broken, the abdomen is 40 mm. long, so that the female appears but little shorter. In its outer appear­ance (fig. 1) this species much resembles H. longirostris Bate (Report ‘Challenger,' Macrura, pl. cxxvii, fig. 2). The much compressed carapace, 17 mm. long as already mentioned, shows its greatest height of 12.5 mm. a little before the posterior border, and, the height decreasing forward, is 8 mm. high at the level of the antero-lateral angle; from the posterior border to the hardly perceptible cervical groove, viz. nearly along its posterior third part, the upper border of the carapace is obtusely carinate, even a little flattened, and on either side of the carina the surfaces of the cardiac region appear somewhat uneven. From this point forwards the carina is sharp and continued into the upper border of the rostrum; from about the middle of the carapace the upper border slopes downward, turning obliquely upwards again at the level of the 2nd antennular segment. The rostrum is narrow, straight or slightly curved, its upper border, as far as one can judge, armed probably with 15 or 16 teeth (figs. 1 and 2) (in fig. 1 there are drawn perhaps 4 or 5 teeth too many); of these teeth the 2nd is placed above the orbital margin, the first 5 or 6 grow gradually a little longer, the following teeth become gradually smaller; the lower border bears a few less teeth, and on either border the distances between the teeth become anteriorly a little longer. From just before the eyes, at either side of the rostral carina, a sharp crest proceeds backward, parallel with the rostrum almost to the middle of the carapace, as in H. typus H. M.-Edw., of which the ova-bearing female from Stat. 46a and the male from Stat. 17 ‘Siboga’ Expedition are lying before me. As regards the sharp crest above the eye, the spines on the anterior border of the carapace, the longitudinal groove posterior to the antennal spine, the shape of the posterior border and of the lower border, this species agrees with H. typus, except that there is no tooth or spine on the postero­lateral angle of the carapace, as in H. spinicauda A. M.-Edw., H. grimaldii Cout., and H. foliaceus Rathb.

 

As in H. typus H. M.-Edw. and H. grimaldii, the 3rd, 4th, and 5th abdominal segments terminate in a spine; the spine of the 3rd, which is slightly curved upward, proves to extend to the posterior margin of the 5th segment; this segment is pressed against it and is sharply carinate; the spines of the 4th and 5th are of equal length, rounded above and little more than half as long as the 3rd. The 1st abdominal segment is carinate on its posterior half; the 2nd, measured on its upper border, is twice as long and obtusely carinate, the tergum being slightly concave on either side of it; the three following segments are nearly of equal length; the 5th, one and a half times as long as the 2nd, is one and a half times as broad with the upper surfaces rounded. Telson (fig. 3) nearly twice as long as the 6th segment, elongate-triangular, tapering, 5 times as long as broad at base, probably terminating in an acute point; its upper surface is flattened, faintly grooved anteriorly, and bears three pairs of small spinules on its pos­terior half, of which the anterior pair is situated just behind the middle and the middle pair nearly as far from the anterior as from the posterior. Uropods a little shorter than telson; inner uropod a little shorter than the outer.

 

In the full-grown male the anterior margin of the 1st pleuron runs from the triangular tooth or prominence at first straight downward, then curves to the lower border, which anteriorly is emarginate, concave, while the greater posterior part is truncate, straight; in the egg-bearing female the anterior margin is regularly curved, convex, the lower straight; the anterior margin of the 2nd pleura, which in the female are much broader than in the male, makes in the latter an obtuse angle with the truncate lower border, but in the female this angle is rounded; the pleura of the 3rd and 4th segments are lunate, excavated on the anterior and convex on the posterior margin, so that they are produced to a point at the infero-anterior angle, this point sharper in the 3rd than in the 4th; the 5th differs from these two segments in having a distinct, slightly concave lower border which makes an obtuse angle with the convex posterior margin, while the anterior angle is rounded; the 6th segment, a little shorter that the 5th, is one and a half times as long as it is deep or high, its lower margin is straight.

 

The eye peduncles and the inner antennæ agree with those of H. typus; the 2nd joint of the antennular peduncle is twice as broad as long. The basal spine of the outer antennæ, which is not visible when the animal is looked at from above, being directed inward and covered by the scaphocerite, reaches almost to the middle of the terminal joint of the antennal peduncle; it is elongate-triangular and produced to an acute point. Not only the outer surface of the spine, but also that of the basal segment is distinctly concave. In H. typus, however, it is only the outer surface of the spine that is concave, not that of the article itself, and while in H. novae-zeelandiæ the lateral margins of the spine are straight, the upper appears in H. typus concave, the lower convex and more prominent. The antennal peduncle reaches barely beyond that of the upper antennæ; the terminal joint is stout, not quite twice as long as broad in the middle on the outer side; the scaphocerite (fig. 4), 14.5 mm. long in the full-grown male, is but little shorter than the carapace and five times as long as broad; it consists of the scale, the inner margin of which is fringed with hairs, and the acuminate spine, which measures almost one-third of the whole length and is distinctly separated from the scale on the inner margin; the outer margin of the scaphocerite is quite smooth, devoid of teeth or spines.

 

The red-coloured incisor and molar processes of the unequal mandibles are distinct, but almost confluent, the molar process much smaller than the other; in one mandible the incisor process is armed between the molar process and the central tooth with 8 acute teeth that gradually grow larger toward the central tooth, and with 10 teeth beyond it, of which the first, contiguous to the central tooth, is the smallest, the second the largest, the six others gradually decreasing in size; in the other mandible (fig. 5) there are only 6 teeth between the molar process and the central tooth and 8 beyond it; the little tooth adjacent to the central tooth is here wanting and the last tooth, with the very small penul­timate on its inner border, appears almost as large as the first; the free borders of the molar process are armed with uncoloured spines that present 2-4 small denticulations on their margin (fig. 6); palp 3-jointed, the terminal joint shorter, but broader than the preceding, and fringed with feathered setæ.

 

The two paragnaths that together form the metastome (fig. 7) are equal, gradually widening forward, with their antero-internal angle broadly rounded, the anterior border S-shaped, with the antero-external angle somewhat angular. Of the two endites of the maxillulæ (fig. 8) the inner is broad, nearly as broad as long, with the outer border covered with spiniform and other setæ that are all feathered, and with microscopical spinules on the outer surface; the other endite is claviform, the smooth convex outer margin bears three setae of unequal length, the distal half of the inner margin is armed with about a dozen strong acute spines and with nearly as many smaller ones, while the proximal half is fringed with feathered setæ; the palp, little shorter than the outer endite and the tip of which is obtuse, is glabrous, except for two setæ inserted on a triangular prominence a little beyond the middle; the longer, anterior seta reaches to the tip of the palp, the other is only half as long; a third spiniform short seta occurs near that prominence on the outer surface.

 

The anterior endite of the maxilla (fig. 9) is divided by a narrow incision into a rounded larger anterior and a smaller posterior part, the posterior endite by a short triangular notch into a very small anterior and a much larger posterior part; palp almost rectangularly bent, glabrous, except for a tuft of long feathered setæ on the rounded tip of the cylindrical distal part; scaphognathite with both extremities rounded, the posterior part shorter than the anterior.

 

The 1st maxillipeds (fig. 10) much resemble those of H. typus (H. Balss, ‘Macrura der Deutschen Tiefsee Expedition,’ 2. Natantia, Teil A, Jena, 1925, p. 248, fig. 22), but the prominence at the antero-internal angle of the falciform exopodite is very short, rudimentary, not segmented; basipodite twice as long as the coxopodite, terminal joint (fig. 11) of the endopodite three times as long as broad at its base; epipodite well developed. The 2nd maxillipeds (fig. 12) resemble also those of H. typus (H. Balss, l. c. fig. 23), but the dactylus that articulates with the distal end of the propodus is but little longer than broad, and thus broader than in that species; its inner (morphologically outer) margin is armed with 8 larger and 5 or 6 smaller spines, while on the outer surface setæ are implanted the inner margin of the propodus bears 5 larger and about a dozen smaller spines; the outer surface is also setose; epipodite well developed. The external maxillipeds (fig. 13) are slender, and project with half the terminal joint beyond the antennal peduncle; the tapering terminal joint, 5.1 mm. long and ten times as long as broad at its base, is thickly covered with pectinated stiff bristles that are arranged in transverse rows; the penultimate joint is 2.7 mm. long, five times as long as broad in the middle and little more than half as long as the terminal, its outer surface covered on the inner half with long setæ; the antero-external angle of the antepenultimate joint bears two spines behind one another, the anterior 0.5 mm. long, the posterior 0.4 mm. The foliaceous exopodite extends almost to the middle of the penultimate joint of the endopodite.

 

The legs of the 1st pair (fig. 14) reach almost to the distal extremities of the antennal peduncle; those of the 2nd are but little shorter, those of the 3rd extend to the same distance, the 4th reach to the distal margin of the 2nd antennal segment, the 5th a little shorter than the 4th. The palm of the 1st legs is a little more than half as broad as long and about 1/8 shorter than the fingers; the lower border of the chela is ridged, and another ridge runs on the inner surface of the palm obliquely from the carpal articulation on to the immobile finger; these ridges are fringed at the inner side with setæ, while the rest of the palm is smooth and glabrous. The carpus bears a short tooth on the distal border at the lower side; exopodite foliaceous, reaching to the middle of the carpus. The chela of the 2nd leg (fig. 17) is one-third that of the 1st; the finger is nearly as long as the palm, which has a much slenderer form than that of the 1st, being 3.6 times as long as broad; the prehensile edges are armed, like those of the 1st legs, with numerous movable spines that are 0.1 mm. long, 12 to 14 on each finger (fig. 18); the carpus appears also longer in proportion to its breadth than in the 1st legs, and the merus is armed at a short distance from its distal extremity with a stout spine 0.3 mm. long. Exopodite not foliaceous, reaching to the middle of the merus.

 

Dactylus of 3rd and 4th legs styliform, half as long as their propodi, termi­nating in a slender, tapering, slightly curved claw, measuring one-fifth the whole length of the dactylus; propodi eight or nine times as long as broad in the middle, slightly narrowing distally.

 

Propodus of 5th legs fifteen times as long as broad; dactylus about one-ninth of propodus, sugar-loaf-shaped, not quite twice as long as broad, clothed on the distal half with many long setæ of different length, some of which are pectinated, others feathered.

 

Endopodite and exopodite of the pleopods rather narrow; of the pleopods of the 2nd pair of the male the stylamblys is 1.2 mm. long, foliaceous (figs. 19 and 20), lamelliform, rounded, twice as long as broad, one margin—not the other—bearing three long setæ, the outer surface near the tip provided with a cluster of small cincinnuli. Appendix masculina (fig. 19) styliform, implanted a little in front of the stylamblys (figs. 19, 20) on a claviform part of the endopodite and 2.25 mm. long, almost twice as long as the stylamblys, and provided on and near the distal extremity with 4 or 5 long, spiniform setæ, of which the longest measures 1.65 mm., three-fourths the length of the appendix; these setæ are pubescent, covered with microscopical hairs."

 

 

(De Man, 1931)

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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