Neotanais armiger Wolff 1956

Neotanais armiger Wolff, 1956

Neotanais armiger Wolff, 1956c:47, fig. 3, pl. 2: figs. 13–16.

DIAGNOSES.—Stages Other Than Copulatory Male: Pleonal epimeres often drawn out into blunt spurs or rounded laterally (see “Intraspecific Variation,” below); *sternites projecting downward, forming long, attenuated midventral spurs. *Chela very large relative to remainder of cheliped; dorsal carpal setae of cheliped scattered, hairlike; ventral carpal setae slender. *Carapace seeming almost triangular in dorsal view, about as long as wide, and very narrow anteriorly. Pleotelson short, often with obtuse angles in margins anterior and posterior to uropods. *First antenna with long slender first article, about 5 times longer than wide and 1.4 times longer than carapace; *article 4 very long, over twice as long as articles 5–7 combined. *Second antenna very slender. Pereopods apparently longer relative to body length than in many other species; *short, terminal propodal spine of pereopods II–IV characteristic: strongly arched and often projecting prominently distally and dorsally in anterior or posterior view; propodal and carpal setae of same legs numerous, slender, and with exceedingly fine setules. Pereonites considerably wider than elsewhere in area over pereopods in dorsal view; *surface generally raised in this area; tapering gradually forward, often being somewhat bell-shaped in dorsal view, especially pereonites 5–7 (see “Intraspecific Variation”).

Copulatory Males (see also “Intraspecific Variation,” below): *Pleonites (epimeres and sternites), pleotelson, second antenna, and pereopods much the same as in other stages. *First article of first antenna slightly longer than carapace. Carapace with prominent rostrum with markedly concave sides; oblique furrows, respiratory chambers, and chelipedal coxae markedly developed in dorsal view; a relatively deep, transverse furrow lying between chelipedal coxae dorsally. *Chelipedal carpus with a few very slender, hairlike setae dorsally and 2 such setae ventrally (for details of chelae see description of allotype and “Intraspecific Variation,” below). *Pereonites 4–6 similar to, but appearing somewhat longer with respect to width than, those of other stages.

DESCRIPTION OF COPULATORY FEMALE (No. 33, Vema Sta. 15–10).—Body (Figure 51A): 9.3 mm long and 5.8 times longer than wide.

Carapace: Short, only 1.1 times longer than wide. Rostrum moderately well developed with markedly concave sides. One anterolateral seta and 1 posterolateral seta present on each side. Anterolateral keels not well developed. Oblique furrows relatively deep. Respiratory chambers and chelipedal coxae well developed in dorsal view, giving carapace a triangular appearance.

Pereonites (Figure 51E): Pereonites 4–6 wider than long and somewhat “bell-shaped” in dorsal view. Areas over pereopods prominently expanded laterally and swollen dorsally.

Pleonites (Figures 51F, 52A): Pleonite 1 a little wider than pleonite 7. Epimeres greatly expanded and tapered laterally. Sternites extended midventrally into long, sharply. pointed spurs, some being slightly posteriorly directed. Bearing occasional long, dorsal epimeral setae, some of which are feathered (all probably feathered originally).

Pleotelson (Figures 51F, 52A): Short, 1.8 times wider than long, and much narrower than pleonite 5. Shape characteristic (but different from animals with short pereonal epimeres—see “Intraspecific Variation,” below).

First Antenna (Figure 52E): First article 4.9 times longer than wide, 1.4 times longer than carapace, and bearing a number of very long lateral setae. Fourth article over twice as long as articles 5–7 combined.

Second Antenna (Figure 52F): Very slender. Second article 4.3 times longer than the third.

Right Mandible (Figure 53K): Third incisive spine naked, slightly irregular at tip, and not swollen basally. Second spine with only a few scattered setules on distal half. First spine fully setulated on both sides.

Left Mandible (Figure 54O): Second incisive spine serrate along entire inner side and distal half of the other. First spine serrate on both margins. Lacinia mobilis with 3 prominent teeth and 1 large irregular posterior lobe.

Second Maxilla: Fixed endite with 2 large, stout bifid spines. Medial setal row composed of 16 (left) and 17 (right) feathered setae and 2 (left) and 3 (right) unfeathered, stout spines.

Maxilliped: Setal formula of palp, (0,0,4+ 1,7,13). Endite with 6 (left) and 7 (right) medial setae.

Cheliped (Figure 52G,H): Carpus with only about 3 very short, fine dorsal setae. Chela noticeably larger in comparison to rest of appendage than in most species, carpus being only 0.7 times as long as propodus (Figure 51D). Dorsal propodal keel moderately well developed. Five large distal teeth on fixed finger brown and rounded; about 40 to 45 small denticles located proximally. Dactylus bearing 4 low, partially fused, and distally directed teeth on cutting surface.

Pereopods II–VII (Figure 55A,E). Propodal and carpal setae numerous, long, slender, and with extremely fine setules visible only with difficulty. Setal formulae of pereopods II and III, (15,12,18,17) and (19,15,19,17). Two long, heavily toothed propodal spines present on pereopod II, whereas pereopods III and IV bear only 1 each. Short, subterminal carpal spine of pereopod II slightly curved and very faintly setulated. Short, terminal propodal spine of pereopods II–IV very stout, strongly curved, bearing numerous strong teeth, and arched upward. Fifteen short, prominently setulated, subterminal spines present on the propodus of pereopod VII.

Pleopods (Figure 55G): Rami long and slender. Protopod bearing 4 small setae. Lateral setae of first exopodal article relatively long and stout. Setal formula, (2,2) (3,9,7) (0,3;0,11,6). Endopodal setae noticeably longer (1.4 times) than article and 11 in number.

Uropods: Slender and longer than pleon. Endopod with 10 and 11 articles on left and right sides, respectively. First article of endopod longer and wider with respect to the succeeding ones than in some species. Exopod about 0.9 times as long as first endopodal article on left side (longer than in many specimens).

DESCRIPTION OF SECONDARY COPULATORY MALE ALLOTYPE (Galathea Sta. 726).—Body (Figure 51B): 10.8 mm long and 5.8 times longer than wide.

Carapace: Bears pronounced and pointed rostrum with strongly concave sides. A single anterolateral and posterolateral seta present on the left side. Ocular lobes prominently visible from above. Anterolateral keels shallow and short. Oblique furrows prominent and a marked transverse crease or furrow present posterior to these. Respiratory chambers and chelipedal coxae strongly developed laterally in dorsal view.

Pereonites (Figure 51G): Very wide in area over pereopods. Sides of pereonites 4–7 sloping gradually posterolaterally with a slight convexity anterior to pereopods.

Pleonites (Figures 51H, 52B): Very similar to those of other stages. Lateral setae not observed (possibly broken).

Pleotelson (Figures 51H, 52B): Similar to that of other stages but posterior margin generally rounded due to fusion of anal area.

First Antenna (Figure 51B): First article 8.7 times longer than wide and about as long as carapace.

Cheliped (chela type B; Figure 54A): Carpus almost straight, only very slightly bent; very swollen centrally; bearing about 6 very slender, hairlike setae dorsally and 2 similar but longer setae ventrally. Dorsal propodal crest finely serrate distally. Fixed finger with 2 rounded teeth on a single eminence proximally, another single tooth slightly distally followed by a very small tooth, and 1 larger tooth distally just before claw. Dactylus with 2 posteriorly directed teeth proximally, followed by 3 small, evenly spaced convexities of decreasing size distally.

Pereopods II–VII: Setae similar to those of other stages. Setal formula of pereopod II, (15,10,17,17). Short, terminal propodal spine of pereopods II–IV similar to that of other stages, strongly curved and serrate on both sides (Figure 55D). Long, terminal propodal spines of same legs bearing prominent teeth on pereopod II (Figure 55D), absent from pereopod III, and bearing finer teeth on pereopod IV. Pereopod VII bearing 14 short, smooth spines subterminally on propodus (Figure 55F).

Uropods. With 10 and 9 endopodal articles on left and right sides, respectively.

INTRASPECIFIC VARIATION.—Variation in Body Length (numbers of individuals considered are in parentheses): Galathea Sta. 726 (Gulf of Panama): preparatory female 1 (1), 6.6 mm; preparatory female 2 (1), 8.8 mm; copulatory female (6), 9.0 to 9.6 mm; copulatory male, chela type A (1), 9.1 mm; copulatory male, chela type A (5), 9.7 to 10.8 mm. Vema Sta. 17–7 (off Chile): Juvenile? (1), 5.8 mm; preparatory female 2 (1), 7.2 mm; copulatory female (1), 8.3 mm; copulatory male (1), 9.0 mm.

Animals collected off Oregon (except for the copulatory female from OSU Sta. 155) were about half as large as equivalent stages of more southerly populations (see below). Copulatory males (6) from Peru and Chile varied from 6.1 to 9.1 mm in length. Specimens from the Atlantic and Gulf of Mexico were smaller than those from the Gulf of Panama (see below).

Pacific Populations: The pleonal sternites vary in length but usually are long. Occasionally short examples have been noted (Figure 52C,D).

The long, terminal propodal spines of pereopod II usually are two in number; however, occasionally only one is found and, in some populations (e.g. at Anton Bruun Sta. 111), one-third to one-half of the animals have three, and occasionally four are found (Figure 55B). The long spines of pereopods II and III usually are present only singly or are absent. No correlation was observed between the number of these spines and the types of pleonal epimeres or other characters described below.

A major difference among the animals was in the shape of the pleonal epimeres in dorsal view. This difference was first noted among the animals from Oregon, one of which, a copulatory female from OSU AD 155, was very large (10.4 mm), heavily calcified, and bearing long epimeral extensions similar to those of the holotype (Figure 53A). The others were shorter (AD 33, copulatory female, 4.4 mm; AD 164, copulatory female, 5.4 mm; AD 118, ?juvenile, 5.8 mm; AD 163, manca 1, 1.8 mm, five juveniles, 2.9 to 3.3 mm, and a copulatory female, 5.2 mm). They also had much shorter pleonal epimeres (Figure 53C) and differently shaped pleotelsons. The setal formulae for pereopods II and VII are as follows: large copulatory female from AD 155, (15,12,20,22) and (6,14,13,11); small copulatory female from AD 33, (10,8,10,13) and (5,8,6,5); and copulatory female from AD 164, (8,6,10,10) and (7,7,6,4). The large female had a single anterolateral seta on either side of its carapace, whereas the others often had two such setae.

A similar difference in pleonal epimeral shape was noted all along the Pacific coast, some stations containing only animals with long epimeres, others with all short epimeres, and still others were mixed. Generally, the animals with short epimeres also were considerably smaller than the others, were less well calcified, and had slightly differently shaped pleotelson and pereonites (cf. Figures 51D–H, 52A–I). The dorsal relief of their pereonites was less pronounced, possibly due to differences in size and/or calcification. Two very large animals were noted with these characters differently shaped and with shorter pleonal sternites as well (copulatory female, 11.3 mm, and copulatory male, 11.4 mm, Galathea Sta. 716—Figures 52C; 53D,E).

The chelae of the copulatory males fell into three categories: (1) those of the largest males (body lengths 9.7 to 11.0 mm—Figure 54A,B); (2) those of smaller males (Galathea Sta. 726, length 9.1 mm, and Vema Sta. 15–39, length 7.1 mm—Figure 54D,E) with chelae types B and A of secondary and primary males respectively and found on males with long pleonal epimeres; and (3) those found on males with short epimeres. The latter type is assumed to be unique to such males (Vema Sta. 15–67, Anton Bruun Sta. 111, and Eltanin Stas. 40 and 75—Figure 54C). These males usually were small in comparison with the other males; however, one male with short epimeres had chela type B described above (body length 9.0 mm, from Vema Sta. 17–7 off Chile).

At first it seemed appropriate to erect a new species for those animals with short pleonal epimeres, short body length, and pereonites and pleotelsons differing from those of the holotype and allotype; however, in view of the very close similarity of other characters among these individuals—the decalcified and broken condition of many important specimens, the presence of one copulatory male with short pleonal epimeres but with chela type B, and the presence of the two very large animals (copulatory female, 11.3 mm, and copulatory male, 11..4 mm, both from Galathea Sta. 716) with short pleonal epimeres and sternites and other slight morphological differences—the situation has become so confused that even after a very extensive study it seems best for the present to retain them all within Neotanais armiger.

With the collection of additional materials, the situation may be clarified. That the animals with short pleonal epimeres are not variants in which the epimeral tips have been eroded is indicated by the presence of dorsolateral epimeral setae (which would have been lost in any such erosion, cf. Figure 53A,C) and by what appears to be a significant difference in the body sizes of the two groups when animals of equivalent age (stage) are compared. The argument that they are not geographic variants is based on the close proximity of the two types off Oregon and their sympatric occurrence at Central American stations.

In chela type A (primary copulatory males—Figure 54D,E) the propodal crest is finely serrate as in chela type B. The fixed finger bears only two teeth: one small tooth proximally and a much larger one distally. The dactylus has a small proximal tooth followed by a much larger one which is followed, in turn, by two or three very small convexities (body lengths: Galathea Sta. 726, 9.1 mm, and Vema Sta. 15–39, 7.1 mm).

The third type of chela (animals with short pleonal epimeres—Figure 54C) is similar to that of the secondary male with long epimeres, but the midsection of the fixed finger is without distinct teeth and is irregular. The dactylus bears a single large, triangular tooth centrally, replacing the three small convexities found in the type A chela. This third type of chela would represent chela type B (secondary male) of the animals with short pleonal epimeres if these animals do in fact represent a distinct species. The body lengths of these males are as follows: Anion Braun Sta. III, 7.4 and 8.5 mm; Eltanin Sta. 40, 9.1 mm; and Eltanin Sta. 75, 6.1 mm.

Atlantic Specimens: Four specimens were examined from the Atlantic Ocean and ancillary waters: a copulatory female (7.6 mm) from CMS Sta. 1597. east of the Florida Keys at 598 m; a copulatory female (6.9 mm) from Alaminos Sta. 5, south of Alabama at 1550 to 1740 m; and a preparatory male (3.9 mm) and a copulatory male (5.7 mm) from Vema Sta. 15–21, on the Caribbean Slope of Panama at 938 m.

All of these individuals have short pleonal epimeres and their body lengths also are appropriately short compared to the holotype and allotype. The animals collected off Florida and Alabama share dorsal pereonite shape with most of the Pacific animals and have long pleonal sternal spines. The Panamanian animals more closely resemble the unusual animals at Galathea Sta. 716 (Figure 53D) in these characters but are, of course, much smaller.

The Florida and Alabama animals have three long, feathered setae on each pleonal epimere (Figure 53J). The Panamanian animals do not have these setae, but they may have been broken off. The female from Florida has the longest anterolateral keels on its carapace of any specimen examined, and it has three long anterolateral setae on each side of the carapace (Figure 51D). The other specimens have the following anterolateral setation on the left and right sides respectively: Alaminos, 2,1; preparatory male from Panama, 1.0; and copulatory male at the same station, 1.1.

The chelae of the Alabama animal and the preparatory male from Panama have a slight convexity midway along the proximal area of the fixed finger, and proximal denticles are absent. The fixed finger of the Florida specimen is straight proximally and lacks such a convexity.

The depths at which these animals are found are relatively shallow, about 600 to 1700 m. In fact, this range includes one of the shallowest records for the family (see “Vertical Distribution” under “Ecology“). In addition, all of these collections of Neotanais armiget are shallower than any Pacific collection; however, other specimens—not available for examination but identified by Dr. Gilbert T. Rowe of the Woods Hole Oceanographic Institution—apparently were collected at 3375 m in the Gulf of Mexico west of Cuba.

Because these animals show such striking similarities to the Pacific populations and because of the impossibility of dividing the Pacific collections into more than one species, these specimens are here assigned to Neotanais armiger.

POSTMARSUPIAL DEVELOPMENT.—Uropods: The endopods contain four articles in mancas 1, seven in juveniles, and nine in preparatory and copulatory females and copulatory males. Occasionally 11 or 12 articles are present in the copulatory stages.

Pleopods: The terminal endopodal setae reach their full length, relative to article length, by the juvenile stage.

Male Gonopore Anlagen: Of 19 recognizable copulatory females with pereonite 7 present, only one specimen had visible gonopore anlagen, and these were very faint. This situation is in marked contrast to this instar in some species where the anlagen frequently are visible, or are visible on other female stages as well.

Male Oostegites: In addition to one juvenile from Anton Bruun Sta. 111 that bore a tiny oostegite on its left pereopod V, both copulatory males at that station bore small rudimentary oostegites on all pereopods II-V. The plates were about the size of those found on preparatory females 1. This is a very unusual circumstance (see p. 225 under “Development”).

DISTRIBUTION.—Neotanais armiger has been collected from Oregon (45°N.) to Chile (40°S.) along the Pacific coasts of North and South America and in the Gulf of Mexico-Caribbean Sea area. Its known depth range in the former is from less than 2000 to over 6100 m and in the latter is from about 600 to 1740 m. More than one species may be included in this material (see above under “Intraspecific Variation” and “Remarks”).

MATERIAL.—See Table 8.

LOCATION OF MATERIAL.—UCZM: Galathea collections including holotype. AMNH: Vema 15–21 (AMNH 14976); Vema 15–39 (AMNH 14977); Vema 15–40 (AMNH 14978); Vema 15–41 (AMNH 14979); Vema 15–46 (AMNH 14980); Vema 15–67 (AMNH 14981); Vema 17–2 (AMNH 14982); Vema 17–7 (AMNH 14983). NMNH: Alaminos 5 (USNM 143205); Anton Brunn 111 (USNM 143200); Anton Bruun 157 (USNM 143201); CMS 1597 (USNM 143206); Eltanin 40 (USNM 143207); Eltanin 75 (USNM 143208); OSU 33 (USNM 143202); OSU 155 (USNM 143203); OSU 163 (USNM 143204).

The hastiger Group of Species

This group comprises only two species, Neotanais hastiger and N. tricarinatus.

STAGES OTHER THAN COPULATORY MALE.—The cheliped is unique: the chela is shorter than usual, thus having a “fist-shaped” appearance. The propodal and dactylar teeth are rounded, variable in size and shape, and brown in coloration. The cheliped is borne generally perpendicular to the axis of the body when preserved, with the animal resembling a cross from above. A notch is present on either side of the carapace between the ocular lobe and the anterolateral keel.

Neotanais tricarinatus differs from N. hastiger in being only about half as large, in having its chelipedal coxae extending posterior to the rear margin of the carapace, and in having relatively long, feathered hairs on each pleonal epimere.

COPULATORY MALES.—Only one type of male is known for each species. The single male known for Neotanais hastiger is from the Bermuda slope, and there is reason to believe that this male may represent a third species in the group; therefore, only the most general characters can be of use in distinguishing this group.

These males differ from other males in the nondimorphic characters listed above for other stages. In addition, the medial side of the chelipedal carpus bears one or more low, rounded protuberances and the ventral chelipedal carpal setae are slender and widely separated in contrast to every other copulatory male known.

The males of Neotanais tricarinatus differ from those of N. hastiger in the following characters: the carapace bears a single middorsal ridge and a midlateral ridge on either side running anteroposteriorly along the anterior half of the carapace. The chelipedal carpus is gradually and evenly curved rather than being bent at right angles. The dorsal propodal margin of the cheliped is turned upward distally rather than being straight.

Neotanais hastiger (Norman and Stebbing, 1886)

Alaotanais hastiger Norman and Stebbing. 1886:113, pl. 23(2).

Neotanais Edwardsi Dollfus, 1898:77, fig. 1 [in part, figured specimen only].

DIAGNOSES.—Stages Other Than Copulatory Male: *Chela “fist-shaped,” very unusual; *carpus, propodus, and dactylus all very short and “stubby” in appearance; carpus with row of 7 to 12 dorsal setae in postjuvenile stages; *position of cheliped when preserved is characteristic, animal resembling a cross when viewed dorsally, chelipeds being held more or less perpendicular to long axis of body. *Pereonites 4–6 generally square or rectangular in dorsal view. *Pleonal epimeres rounded or slightly acute laterally; *sternites with prominent midventral spurs appearing triangular in lateral view. *Pleotelson relatively longer than in many species. *Carapace bearing a notch laterally on either side at forward end of anterolateral keels; 2 to 4 anterolateral setae present.

Copulatory Males: See “Description of Copulatory Male O,” below.

DESCRIPTION OF PREPARATORY FEMALE 1 A (Gay Head-Bermuda Transect; WHOI B. Sta. 95).—Body (Figure 56A): 7.6 mm long and 6.8 times longer than wide.

Carapace (Figure 56A,D): 1.3 times longer than wide. Anterolateral keels and oblique furrows both prominent. Two anterolateral setae and one posterolateral seta present. Notch present in keel on each side of carapace over setae. Anterior margins of carapace on each side of rostrum concave in dorsal view; rostrum prominent.


Pereonites (Figure 56A,I): Pereonites 5 and 6 generally quadrangular with moderate expansions above pereopods. Pereonite 5, 1.2 times wider than long.

Pleonites (Figures 56A,G,H, 57A): Rounded and somewhat flared laterally; each epimere bearing 2 or 3 slender hairs of moderate length dorsally. Hairs apparently not feathered as in Bermudan female but with at least a few irregular setules visible under high magnification. Sternites expanded into blunt, posteriorly directed, midventral spurs. Sternites separated ventrally by relatively deep furrows.

Pleotelson (Figure 56A,G,H): Long in comparison to many species; width-length ratio, 1.4. Edges anterior to and posterior to uropods convex, a relatively prominent concavity lying on either side of median posterior prominence. A long, very fine hair located posteriorly on either side over these concavities.

First Antenna (Figure 57D): First article 4.2 times longer than wide.

Second Antenna: As in Figure 57E,F.

Right Mandible (Figure 57G): Third incisive spine sharply pointed, second spine only serrate for a short distance distally along inner side, and first spine similarly toothed on outer side but serrate along entire inner margin.

Left Mandible (Figure 57H): Incisive spines as on right side. Lacinia mobilis composed basically of 2 large teeth and a long, pointed posterior lobe.

Labium: As in Figure 58A.

First Maxilla: As in Figure 58D.

Second Maxilla (Figure 58B): Fixed endite with 2 bifid terminal spines. Medial setal row with 21 apparently naked setae and 3 smooth, stout, pointed spines.

Maxilliped (Figure 59B): Setal formula of palp, (1,0,5+1,6,10). Five medial filter setae present on endite.

Epignath: As in Figure 58C.

Cheliped (Figure 58E,F): Carpus very short relative to propodus, only 0.6 times the length of the latter; bearing 8 dorsal setae. Fixed finger of chela with 5 low, rounded, brown teeth; proximal denticles absent, teeth taking up most of the length of the cutting edge; claw short, blunt, and brown. A cluster of 4 setae present ventrally; dorsolateral setae grouped together to form a cluster of 3. Dorsomedial propodal seta at articulation of dactylus unusually long. Medial dactylar seta with fine setules. Dactylus with 3 low, rounded, and smooth teeth; shorter than fixed finger. Chela resembles a clenched fist and is generally held more or less perpendicular to body when preserved.

Pereopods II–IV (Figure 59C,D): Short, terminal propodal spine slightly curved, very stout, and with 3 large teeth on one side and 9 smaller ones on the other. Long, terminal propodal spines not present. Setae moderately stout, tapered to fine points, and bearing fine but prominent setules. Setal formulae of pereopods II–IV, (4,4,8,7), (9,10,8,10), and (10,10,10,10). Proximal end of propodus of at least pereopods II and IV bearing a few large, ventrolateral serrations. Short, subterminal carpal spine slender, straight, and devoid of any armament (see Figure 59E).

Pereopods V–VII: Setal formulae, (9,7,7,9), (8,8,8,8), and (8,8,6,6) respectively. Dactyli of all 3 appendages fringed with very small terminal teeth (Figure 60D) continuing proximally and merging imperceptibly with more proximal lateral rows of denticles. Distal dactylar cleft very wide. Propodus of pereopod VII lacking short subterminal spines.

Pleopods (Figure 59L): With 8 terminal endopodal setae; seta length 1.7 times that of endopod. Setal formula, (2,1) (3,8,7) (0,2;0,8,8). Endopod with a distinct row of terminal setae.

Uropods (Figure 56A,H): Each with 9 endopodal articles. Exopods of left and right sides l.l and 0.9 times longer, respectively, than first endopodal article.

DESCRIPTION OF COPULATORY MALE O (Bermuda Slope; WHOI B. Sta. Ber. 7).—This is the only known copulatory male of the species. Caution should be exercised in using this description for comparative purposes because the Bermuda female differs from North American populations (as well as from others), and it can be assumed that the male varies as well (see “Intraspecific Variation,” below).

Body (Figure 56B): 8.1 mm long; width-length ratio, 6.0.

Carapace (Figure 56B,C): Rostrum blunt and anterior border almost straight on either side. Keels straight and parallel, leading into deep oblique furrows posteromedially. Anterolateral setae 5 in number, posterolateral seta single. Respiratory chambers and chelipedal coxae greatly inflated laterally in dorsal view.

Pereonites: Pereonites 3–7 rectangular in dorsal view.

Pleonites (Figures 56A, 57C): Generally rounded laterally and bearing one or two setae without setules. Sternites similar to described female midventrally.

Pleotelson (Figures 56A,M, 57C): Appearing considerably shorter and more angular than that of described female and bearing a low midventral prominence anteriorly.

First Antenna: First article 4.8 times longer than wide.

Cheliped (Figures 56B, 59A): Carpus strongly bent proximally and bearing a row of about 9 very small dorsal setae, 2 slender and very widely separated ventral setae, and a sizable medial protuberance at level of bend. Propodus straight dorsally with proximal two-thirds forming an irregularly edged keel. Fixed finger about as long as dactylus and bearing a large tooth proximally and several low irregularities on grasping surface beyond. Dactylus with a very small, proximal tooth and an extremely large, triangular distal tooth. Fingers neither twisted nor bent.

Pereopods II–VII: Setal formula of pereopod II, (5,3,7,5). Long, terminal propodal spines of pereopods II–IV absent. Short, terminal propodal spine of pereopods II–IV and short, subterminal carpal spine of pereopod II both short, slender, and apparently naked or with only very fine setules. Propodus of pereopod VII bearing row of 8 short, prominently serrate, subterminal spines. Dactylar spines of pereopods II–IV long, slender, and bent at tips. Dactyli of pereopods V–VII all bearing very fine terminal teeth (see Figure 60C).

Uropods: Each with 9 endopodal articles.

INTRASPECIFIC VARIATION.—Stages Other Than Copulatory Male: In addition to the usual intrapopulational variations expected in Neotanais, noticeable and consistent differences were observed among the six populations of which representatives were available for study. These differences are described and intraspecific relationships are summarized here.

Holotype, Preparatory Female 2 (Labrador Sea): This animal is almost identical with the described female A from the Gay Head-Bermuda Transect. The pleotelson (Figure 56K) and the dental arrangement on the chelipedal propodus (Figure 58G) are slightly different.

The following are additions or corrections to the description given by Norman and Stebbing (1886). The body length from rostrum to tip of pleotelson is 7.8 mm and not 5 mm as published. The carapace is illustrated very poorly in the original description and closely resembles Figure 56A except that there are three anterolateral setae on either side. Norman and Stebbing correctly observed that the large, toothed terminal spines are absent on the propodi of pereopods II–IV. Short terminal spines on the same articles are similar to Figure 59D (enlargement) and the subterminal carpal spine of pereopod II resembles Figure 59E.

Norman and Stebbing do not mention a row of short propodal spines on pereopod VII, and these legs could not be examined. The dactyli of the posterior pereopods are not unique as suggested by these workers but are typical of the genus.

Other Populations: Following are representative body lengths (number of animals considered indicated in parentheses). WHOI B. Sta. 95: juveniles (2), 4.7 and 5.2 mm; copulatory female (1), 9.6 mm. WHOI B. Sta. 85: preparatory female 1 (1), 6.7 mm. Sarsia Sta. 44: manca 2 (2), 3.9 and 4.0 mm; preparatory female 1 (1), 4.9 mm; preparatory female 2 (2), 7.3 and 7.6 mm; copulatory female (2), 7.1 and 7.4 mm. WHOI B. Sta. Ber. 7: preparatory female 2 (1), 7.1 mm; copulatory male (1), 8.1 mm.

The long anterolateral and posterolateral setae on the carapace are, respectively, 4 or 5 and 1 in number in the Bermudan specimens (Figure 56B,E) as contrasted with 2 and 1 for North American Slope populations (Figure 56A). The specimen collected by the Noratlante in the Bay of Biscay exactly resembles the Bermudan population in this character.

The pereonites (Figure 56I,J) of the animals collected off North America and Bermuda were more nearly quadrangular in dorsal view than those from Europe and Africa. The latter appeared to be relatively wider. This difference, not reflected in width-length ratio, is due to the configuration of the anterior and posterior areas of the pereonites.

The pleonites of some European specimens (Bay of Biscay) have more expanded and flared epimeres in dorsal view than do western North Atlantic populations (Figure 56H,N,O). The Bermudan female has at least three strikingly long and heavily feathered hairs or setae on each epimere (Figure 56F), whereas in North American specimens they appear shorter and have few setules (Figure 56H; but see Bermudan male, Figure 56B). The midventral spurs vary, some being relatively blunt and others pointed (Figure 57A,B). One specimen from the Bay of Biscay has midventral spines of appreciable length.

The pleotelson (Figure 56H,K,L) usually appears shorter with respect to width in dorsal view in specimens from European populations than in those animals from the North American Slope and Bermuda.

In female C (North America) the two proximal incisive spines of the right mandible are serrate on both sides of the tip only (Figure 57G,L,M); female F (Bay of Biscay) has a slightly irregularly tipped second spine and the first spine bears teeth only proximally on the inner side.

The number of setae in the medial row of the second maxilla varies from 18 to 22 in three individuals examined, but the number was 33 in female F (Bay of Biscay), a remarkable difference. In no case were setules observed on these setae. Stout spines associated with this row were two or three in number, sometimes on the same animal.

See Figure 58F–J for the variation in number, size, shape, location, and color of propodal and dactylar teeth on the chela. The variation illustrated is the maximum encountered and many animals showed much less variation. The dactylus is slightly longer than the propodus in the female from Bermuda.

No notable variations in numbers of carpal and propodal setae were observed for pereopods II–VII. The short, terminal propodal spines of pereopods II–IV vary considerably in shape (Figure 59D,I,J) but are always prominently toothed. The row of short, subterminal propodal spines on pereopod VII is absent from North American populations but present in populations from the Bay of Biscay (Figure 59K) and Bermuda. Long, terminal propodal spines are missing from all populations investigated. Short, subterminal carpal spines of pereopods II are always naked; however, in the European populations they are more slender than in others (Figure 59E,F). The anterior propodal setae of pereopods II–IV were considerably more bluntly tipped in the Bermudan female than in any other population (Figure 59G,H).

The dactyli of pereopods V–VII exhibit interesting differences. In all animals examined from North American populations, the dentition is the same as for female A above: all three dactyli have very fine teeth (Figure 60D). Specimens from the Bay of Biscay have relatively large teeth on all three pereopods with some variation among them (Figure 60E,F). Female N from Bermuda has coarse teeth on the dactyli of pereopods V and VI, whereas fine teeth are present on pereopod VII (Figure 60A–C). (Copulatory male O from Bermuda, however, has fine teeth on all of these dactyli.)

In summary, there are various combinations of characters shared among the six populations sampled. The Bermuda Slope and Biscay populations shared the presence of a row of short propodal spines on pereopod VII. North American animals and Neotanais tricarinatus (q.v.) lack such a row. All animals from the western North Atlantic have relatively square pereonites in dorsal view, whereas the more anteriorly tapered shape is shared by Biscay and West African populations (and Neotanais tricarinatus). Western Atlantic populations have truly blunt pleonal epimeres, whereas in Biscay and African animals these structures are slightly attenuated.

The presence of these overlapping combinations of morphologic features shared among the populations and the limited sample size make it difficult to recognize specific differences, if present, among these populations.

The Bermudan female differs from North American speicmens mainly in the dentition of its chelae; the presence of a row of short, subterminal propodal spines on pereopod VII; the number and length of anterolateral setae on the carapace; and the feathering of its pleonal epimeral setae. The anterior propodal setae of pereopods II–IV are bluntly tipped in the Bermudan female, whereas they are pointed in North American animals (and all others). These are considerable differences for populations separated by only a few hundred miles, and the Bermudan population eventually may be determined to be distinct.

The single animal from West Africa is almost certainly conspecific with the European populations with which it was most similar in examinable characters: pereonite and pleonite shape and midventral configuration of the pleotelson; the dactylus of the chela bears four round teeth; and the propodus has five low, slightly raised, round teeth. In dorsal view, however, the pleotelson was most similar to the North American populations. The dactyli on pereopods V and VI had coarse teeth. The carapace and the pereopods VII were missing, preventing comparison of these structures.

The European specimens differ from North American populations most significantly in the presence of a row of short, subterminal propodal spines on pereopod VII. The populations on the North American Continental Slope are almost identical with the holotype population near Greenland. If the eastern Atlantic populations are later determined to represent a distinct species, the name Neotanais edwardsi will be reinstated for them with the Travailleur specimen as the holotype.

POSTMARSUPIAL DEVELOPMENT.—Male Gonopore Anlagen: Of the 13 specimens of this species examined (excluding mancas and copulatory males), three had evidence of male gonopore anlagen as clear, decalcified spots. These were a copulatory female, a preparatory female 1, and a preparatory female 2. In Neotanais, preparatory females infrequently display these anlagen so clearly.

Uropods: Mancas 1 have four endopodal articles; mancas 2, six; juveniles, seven; and copulatory males and females, nine.

Pleopods: The pleopods continue to increase in number of terminal endopodal setae from five in the juveniles (B and C, WHOI B. Sta. 95) to eight in the preparatory females 1 (A, same station), to 12 in the copulatory female (D, same station), the largest number observed. The ratio of terminal setal length to endopodal length remains about the same through development (juveniles B and C, 1.7 and 2.0 respectively; preparatory female 1 A, 1.7; copulatory female D, 1.7). The ratios of preparatory female 2 N and copulatory male O, WHOI B. Sta. Ber. 7, were 1.9 and 1.7 respectively.

MATERIAL.—See Table 9.

LOCATION OF MATERIAL.—BMNH: holotype, Valorous. FNMNH: Travailleur collection. NMNH: Noratlante 019, E003 (USNM 143212); Noratlante 026, E0004 (USNM 143213); Noratlante 042, E006, (USNM 143214); Noratlante 109, B015 (USNM 143215); Sarsia 33 (USNM 143216); Sarsia 44 (USNM 143217); WHOI 95 (USNM 143209; WHOI Ber. 7 (USNM 143210); WHOI 146 (USNM 143211).