Zelinkaderes floridensis Higgins 1990

Zelinkaderes floridensis

DIAGNOSIS.—Zelinkaderes, adult trunk length 300–435 μm, trunk width 42–60 μm, about 14 percent of trunk length, with middorsal spines on segments 6, 8, 10–13, length of each nearly equal to that of segment of origin; cuspidate spines present laterally on segments 7, 10, 11; aciculate spines present laterally on segments 1–13; middorsal gland (cuticular scar) on segment 3, none evident on segment 4, subdorsal glands (cuticular scars) on segment 12; Lateral terminal spines shorter than lateral terminal accessory spines.

DESCRIPTION.—Trunk: Adult (Figures 1–68) trunk length 355–420 μm; x 17 (mean of 17 measurements) = 392.1 ± 20.7 μm. The maximum sternal width is indeterminable because the lateral tergal-sternal junctions are not evident; however, an estimate of this width is 42–60 μm, about 14 percent of the trunk length. The standard width, normally defined as the distance between the anterolateral margins of the sternal plates of segment 12, cannot be determined for the same reason given above. A substitute standard width measurement, based on the distance between the lateral margins of the cuspidate spines of segment 11, is 46–58 μm, x 17 = 52.0 ± 3.5 μm, 12.4–14.5 percent of the trunk length.

Segment 2 measurements are difficult to assess by light microscopy because of the segment's apparent basal fusion with segment 3. Estimates of the length of this segment are 16–24 μm, x 14 = 21.4 ± 2.0 μm. The midventral placid (Figures 1, 18) is about twice as wide as each of the remaining 15 placids.

Segment 3 is 22–30 μm in length, x 16 = 25.8 ± 2.6 μm. The anterior margin, adjacent to the placids, lacks cuticular hairs; the posterior two-thirds of the segment is evenly hirsute. When the cuticle is viewed with phase contrast optics, there is a distinctive internal striate pattern (see Figure 77). Cuticular hairs at the posterior margin of the segment extend beyond the intersegmental junction as a pectinate fringe. The arthrocorium, as in all of the following segments, often is expanded, more widely separating the adjacent segments (Figures 1, 2). The surface of the arthrocorium typically has transverse rows of minute tubercles (Figure 23). A distinct pachycyclus is absent; the cuticle appears to be uniformly thin. An exception to this is the thickened anteroventral margin of segment 13 in the female (see description of segment 13).

Segment 4 is 24–30 μm in length, x 16 = 27.4 ± 1.9 μm. A prominent middorsal cuticular scar (pore leading to a dorsal gland) is present (Figures 2, 21). Laterally, two in-line, less hirsute patches of cuticle appear as interruptions in the otherwise uniformly hirsute cuticle (Figure 14).

Segment 5 is 24–32 μm in length, x 16 = 26.7 ± 2.8 μm. The middorsal cuticular scar is absent, and only a single patch of less hirsute cuticle is present laterally. Beginning with this segment, and continuing through segment 13, there is a midventral fissure where the morphological lateral edges of the tergal plate meet. The cuticle in this area appears slightly thicker than elsewhere (Figure 1).

Segment 6 is 24–30 μm in length, x 16 = 27.5 ± 2.0 μm. A transverse row of three paired patches of less hirsute cuticle are situated anterodorsally. As in segment 5, a single patch is present laterally at midlength, and an additional sensory spot is present slightly more posteroventrally (Figure 14). A middorsal spine 20–29 μm in length, x 17 = 24.4 ± 2.4 μm, extends from the incised posterior margin of the segment. A sensory spot is present on each side of this spine (Figures 22, 23) and all other middorsal spines. As in all other spines, the cuticular surface is covered basally with minute tubercles (Figure 23) and distally with imbricate, short cuticular hairs (Figures 22, 23, 28–31).

Segment 7 is 26–32 μm long, x 16 = 28.9 ± 2.9 μm. It is similar to segment 6 but with two, in-line, sensory spots and no lateral sensory spot (Figure 14). A cuspidate spine, 21–28 μm long, x 17 = 24.5 ± 2.0 μm, is present ventrolaterally (Figures 1, 2, 14, 18). The basal half of a cuspidate spine is broad, narrowly oval in cross-section, and hirsute; the distal portion is narrow, round in cross-section, and terminates with a pore similar to that shown in Figure 29. Similar spines are present on segments 10 and 11.

Segment 8 is 28–33 μm long, x 16 = 30.1 ± 1.5 μm. As in segment 6, there is a middorsal spine, which is 27–35 μm long, x 17 = 31.2 ± 1.5 μm. Also, in all other respects it is similar to segment 6.

Segment 9 is 30–36 μm long, x 16 = 32.0 ± 1.9 μm. This segment lacks a middorsal spine, but otherwise is like segment 8.

Segment 10 is 28–36 μm long, x 16 = 32.6 ± 2.4 μm. It is similar to segments 6 and 8 in having a middorsal spine, which is 32–40 μm long, x 16 = 22.5 ± 2.2 μm. A transverse row of three paired-patches of less hirsute cuticle are situated anterodorsally, and there is a lateral patch as on segment 9, but no sensory spot is present: two lateral spines are situated in its place. The dorsalmost of the two spines is cuspidate, similar to those of segment 7 and 11, and measures 26–34 μm, x 17 = 29.3 ± 2.7 μm. Ventral to the cuspidate spine is an acicular spine, 18–28 μm long, x 17 = 22.5 ± 2.2 μm. Although in ventral aspect, these two spines appear to be in positions equivalent to those of the following segment, they clearly are more elevated as can be seen in lateral view (Figures 14, 27). In ventral aspect, females have paired single pores situated anteromesial to the ventrolateral acicular spine.

Segment 11 is 32–42 μm long, x 16 = 37.0 ± 2.9 μm. It also has a middorsal spine 40–50 μm long, x 17 = 43.5 ± 2.8 μm. The anterodorsal margin of this segment is similar to those preceding it, but unlike segment 10, there are two, in-line, patches as in segments 4 and 7 (Figure 14, 27), and a sensory spot (Figures 14, 27, 30) ventral to the posteriormost lateral patch. This sensory spot appears to be in the same relative position as the cuspidate spine of the preceding segment. Below and slightly posterior to this sensory spot are two lateral spines. The most dorsal of the two spines is acicular, measuring 24–28 μm, x 17 = 26.3 ± 1.2 μm. The most ventral of the two spines is cuspidate, measuring 26–37 μm, x 17 = 30.1 ± 2.5 μm. As in the preceding segment, the ventral aspect shows paired single pores positioned anteromesial to the spines in the female (Figure 1).

Segment 12 is 30–40 μm long, x 16 = 34.9 ± 3.1 μm. As in segments 6–11 three patches of less hirsute cuticle are present in a transverse row anterodorsally. A lateral patch is posterior to the ventralmost of the former patches and a sensory spot is located both dorsally and ventrally to the lateral patch (Figure 14). This segment has a middorsal spine 33–44 μm long, x 17 = 37.4 ± 3.6 μm. In the male this and the 2 lateral spines on the segment, are flexible (Figures 3, 4, 14, 38), and distally segmented or moniliform in appearance. The middorsal spine also may be slightly shorter in males, 32–40 μm, x 12 = 36.1 ± 2.5 μm, than in females, 34–44 μm, x 5 = 40.6 ± 4.0 μm. The lateral spine on segment 12 is slightly elevated to nearly a midlateral position (Figure 14) and its length is 24–38 μm, x 17 = 33.2 ± 3.0 μm. Although this spine may tend to be slightly longer (and flexible, as noted previously) in the male 30–38 μm, x 12 = 33.8 ± 2.3 μm, than in the female 24–34 μm, x 5 = 31.8 ± 4.4 μm, the differences are not significant. Subdorsally, near the posterior margin, on each side of the middorsal spine of both males and females, there is a unique cuticular scar. No evidence of any surface structure could be seen by scanning electron microscopy, but light microscopy revealed a series of four pores within this scar (Figures 2, 4).

Segment 13, the terminal segment, is 30–35 μm long, x 16 = 32.6 ± 1.8 μm and strongly tapers to the base of the midterminal spine 230–290 μm long, x 16 = 262.4 ± 18.3 μm. The length of the midterminal spine tends to be larger in males, 240–290 μm, x 11 = 270.7 ± 14.8 μm, than in females, 230–255 μm, x 5 = 244 ± 9.6 μm. The MTS/TL (ratio of midterminal spine length to trunk length expressed as percent) is 55.4–77.0 percent, x 16 = 67.4 ± 7.4 percent. A middorsal spine 64–80 μm long, x 17 = 72.1 ± 4.0 μm is present, extending well beyond the margin of the terminal segment. Lateral terminal spines are 44–54 μm long, x 17 = 48.4 ± 2.9 μm. The LTS/TL (ratio of lateral terminal spine length to trunk length expressed as percent) is 11.1–13.8 percent, x 17 = 12.4 ± 0.7 percent. Prominent sensory spots are present mesial to each lateral terminal spine (Figures 14, 31). Lateral terminal accessory spines, are slightly longer than, and lie dorsally adjacent to, the lateral terminal spines, 64–76 μm long, x 17 = 68.1 ± 3.4 μm. The LTAS/LTS (ratio of lateral terminal accessory spines to length of lateral terminal spines expressed in percent) is 124.5–155.1 percent. Although there still appears to be no separation between the tergal and sternal plates, there is a distinct ventral margin separated from the remainder of the segment's cuticle (Figures 1, 3), giving the appearance of sternal plates much shorter than the presumptive tergal plate.

The cuticle at the anteroventral margin of segment 12 in the female is thickened as a pachycyclus and has a distinctive morphology (Figure 1). Near the lateral margins, there is an arched region (Figures 33–35), which appears to form the anterior margin of a flap of cuticle covering an opening presumed to be a gonopore. A sensory spot lies lateral to each flap (Figures 34, 35). In the male (Figure 3), the cuticle is not thickened to form a distinctive structure, which can be seen in light microscopy; but SEM photographs (Figures 36, 37) reveal a modification of the cuticular surface in the position comparable to the cuticular flap of the female. A gonopore is assumed present in this area of cuticle in the male.

Head: Segment 1 is not always described in taxonomic publications, but in the case of Zelinkaderes floridensis sufficient material is available to present the following information. The kinorhynch head consists of two parts: an evertable, spherical region bearing up to 7 rings of scalids, and a mouth cone centered within the spherical head from which it is protruded anteriorly through the everted head in order to feed. The determination of the ring in which the scalid is located is complicated, at least in Zelinkaderes, by the extent of the attachment area. If, for example, the ring assignment is based on the anteriormost point of a scalid's origin, this may not be commensurate with the ring assignment based on the posteriormost point of the scalid's attachment, where it becomes free from the head, and usually where the second of the two elements begins. In this paper, the assignment of scalids to a ring has been determined by the point at which the posterior margin of the basal segment attaches to the article of the head or introvert.

As in all members of the phylum Kinorhyncha, the primary scalids are the largest scalids. Insofar as they are the organizers of the scalid pattern, they are the directive scalids, and with reference to the diagram (Figures 5, 6) constitute the first row of spinoscalids (indicated by solid triangles pointed radially to indicate their posteriorly directed orientation when the head is everted). Scalid arrangement is organized into 5 odd (shaded) and 5 even (unshaded) sectors as shown in Figures 5, 6. Each sector is divided into radii designated A,B,C, and D. D-radii are the directive radii established by each of the 10 primary scalids and which delimit each sector. The middle radius of each sector is referred to as the B (basal)-radius. On the sides of the basal radius are the A- and C-radii. As just noted, scalid ring 1 contains the 10 largest scalids. Their polar-coordinate position is “1–1–D through 10–1–D” which indicates first, the sector number (1–10), second, the ring number (1), and last, the radius (D). Sometimes the radius designation(s) may be replaced by the terms “odd” or “even.” The directive (position of primary scalid) D-radius follows the C-radius of a given sector (on the clock-wise sequence of the four letters (A-B-C-D).

The 10 primary spinoscalids of the first ring (anteriormost) (Figure 7) (shown as solid triangles in Figures 5 and 6) are about 55–65 μm long, a multi-element basal fringe (Figures 5, 7, 16) extends as much as one third the spinoscalid length. The distal portion of the spinoscalid appears partially septate along its inner margin and terminate in a blunt tip with a pore (Figure 7). These and at least some other spinoscalids consist of a basal unit and an articulating distal unit. The basal unit is provided with a pectinate fringe at its origin.

Superficially, there appear to be 10 spinoscalids in the second ring. Five of these, located on the B-radii of odd sectors (1, 3, 5, 7, 9), are indicated by solid circles, assigned to the second ring (Figures 5, 6), have short attachment planes (Figure 8), and extend freely from the head more anteriorly than do those of a second set. The second set of 5, located on the B-radii of even sectors (2, 4, 6, 8, 10), are indicated by solid ovals, have longer attachment planes (Figure 11), and extend freely from the head more posteriorly (at the same level as the A- and C-radii scalids of the odd sectors); therefore, they are assigned to the fourth ring along with the A- and C-radii spines of the odd sectors. Both sets of 5 scalids are extremely similar (Figures 8, 11), appear to originate immediately posterior to the primary scalids of the first row, have a prominent 3–element basal fringe (Figures 5, 8, 11, 19), and smooth distal elements with pointed tips. The length of the odd-sector scalids is about 35–40 μm, the even-sector scalids are slightly shorter, 30–35 μm.

The 10 spinoscalids (Figure 11) of the third ring (shown as solid squares in Figures 5 and 6) are located on the A- and C-radii of even sectors (2, 4, 6, 8, 10). These spinoscalids are about 30–35 μm long, have a single-element basal fringe and fringed inner margins (Figures 5, 11, 16) as in A- and C-radii, odd-sector scalids of the fourth ring. Like the scalids of the second ring, the third-ring scalids are pointed at the tip.

The 15 spinoscalids of the fourth ring (shown as solid ovals in Figures 5 and 6) consist of 5 spinoscalids located on the B-radii of even-numbered sectors (see the paragraph concerning the second ring), and 10 additional spinoscalids occupying positions on the A- and C-radii of odd sectors. The latter 10 spinoscalids (Figure 12) are extremely similar to the 10 spinoscalids of the A- and C-radii, even-sector spinoscalids of ring 3 (Figure 11).

In those genera (Pycnophyes, Kinorhynchus, and Echinoderes) more carefully studied, 7 rings appear to be present in adults and as few as 4 rings in the earliest juvenile stage. Trichoscalids, typically 14 in number, occupy the posteriormost ring (ring 7) in kinorhynchs. Although classically (Zelinka, 1928:23) these sensory structures are hirsute, juvenile-stage trichoscalids typically lack this character, remaining simply smooth and highly flexible. The 14 simple, smooth, highly flexible scalids (Figures 10, 12) in the posteriormost ring of Zelinkaderes floridensis (indicated by open circles with short radii in Figures 5 and 6), are assumed to be homologous with the juvenile protrichoscalids and, therefore, are assigned to ring 7. Nine of the 14 trichoscalids (one on each of the A- and C-radii of sectors 2, 4, 8, and 10, and a single trichoscalid on the B-radius of sector 6 (Figure 13) are slightly elevated from the remaining 5 trichoscalids on the B-radii of sectors 1, 3, 5, 7, and 9 (Figure 10). The 9 even-sector trichoscalids are about 20 μm in length, have a modest amount of basal fringe, and an elongate, flexible distal element, which is pointed. The 5 odd-sector trichoscalids are slightly longer and more robust. Thus, the general appearance of the scalid pattern in Z. floridensis is (1) an anteriormost (ring 1) series of 10 primary spinoscalids, which define 10 sectors; (2) each sector with a (median) secondary and two (lateral) tertiary spinoscalids centered between the primary scalids apparently successive rows; and (3) a quaternary ring of 14 juvenile-like protrichoscalids, 9 of them elevated slightly with respect to the remaining 5. Superficially, if not actually, there appears to be only 4 rings of scalids in this genus.

There are 9 anteriorly directed, oral styles surrounding the mouth cone, the terminus of which is the mouth (Figures 5, 14, 16, 39–43). In the polar-coordinate diagram of the head (Figure 6), the positions of the 9 oral styles are indicated by the short, broad arrows, pointing toward the center of the circle, located on all B-radii except that of sector 1 (the middorsal oral style is missing); thus, they alternate with the positions of the 10 primary scalids located on all D-radii. Each oral style of Zelinkaderes floridensis has two segments, a basal element, about 25 μm long and a distal element about 5 μm long. The basal element of the style bears a pectinate fringe similar to the basal element of a spinoscalid (Figures 7–13), and the pectinate fringe typical of the posterior margin of most trunk segments. Near the base, each style is oval in transverse section; at about midlength the lateral edge forms what appears to be a hollow flange leading to the distal element (Figures 5, 16, 17). Since there is a pore (Figure 17) at the terminus of the distal element, these lateral flanges may be ducts leading to the pore.

Within the mouth cone are 20 pharyngeal styles arranged in 3 (possibly 4) rings. The innermost ring (ring 1) consists of 5 long, strongly cuticularized, longitudinally ridged pharyngeal styles (Figures 39–41, ps1) that may be partially extruded during the protrusion of the mouth cone. These originate in the epithelium of the pharynx near the cuticularized oral crown at the anterior end of the pharyngeal bulb. The midventral pharyngeal style of ring 1 appears to oppose an oral style (Figures 6, 40); therefore, it is assumed to be on the B-radius of sector 6, and the remaining 4 pharyngeal styles of ring 1 occupy B-radii positions on other even sectors. This assumption is supported by TEM studies of Echinoderes aquilonius Higgins and Kristensen, 1988, and Pycnophyes greenlandicus Higgins and Kristensen, 1988 (Kristensen and Higgins, in press). First ring pharyngeal styles are indicated on the first ring mouth cone (Figure 6) by asterisks.

Alternating with the first ring are 5 weakly cuticularized pharyngeal styles (Figure 39, ps2) of ring 2. These apparently are on B-radii of odd sectors, and are indicated in the diagram (Figure 6) by larger arrowheads.

The remaining 10 pharyngeal styles (ps3) occur in pairs, each pair originates between the pharyngeal styles of ring 2 (ps2) and are indicated by narrow arrowheads. One of each pair has its origin closer to the origin of ring-2 pharyngeal style, the other originates farther away. The result is a slight off-set of these paired oral styles so that they appear to be in separate rows (which is a possibility, but they appear to be morphologically identical). Hence, when the pharyngeal epithelium is hyper-extended, pharyngeal styles of the ps3 units are on either side of each ps2 unit (Figure 39), one appearing slightly posterior to the other.

JUVENILE STAGES.—Juvenile stages are rarely described in taxonomic publications. The quality and quantity of material of Zelinkaderes floridensis, however, permits an analysis of the entire life history of this species. A total of 62 juvenile specimens were studied, and among them were at least one representative of each of six stages (J-1 through J-6, Figures 45–62), which are included below as a part of the species description.

J-1 Stage: The first stage in the life history of Zelinkaderes floridensis (Figures 45, 46, 57–59) juvenile development is represented by a specimen 165 μm long (RH 1561.21, USNM 235451). Its estimated standard width is 40 μm, the SW/TL 21.1 percent. Middorsal spines (Figures 46, 59) are present on segment 6 (42 μm long), segment 8 (41 μm long), segment 10 (40 μm long), and segment 11 (110 μm long); the midterminal spine is 170 μm long, 73.9 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (20 μm long) and acicular lateral spines on segment 10 (42 μm long). The slightly protruding spines at the lateral margins of segment 11 may be the anlagen of the lateral terminal accessory spines, based on the observation that these, the more dorsally displaced lateral spines of the terminal segment, are also the most prominent throughout the life history, including the adult stage. The only other distinguishing feature of this stage is the presence of a cuticular scar middorsally on segment 4. Placids are apparent and commensurate with their distribution in the adult. Four rings of spinoscalids are present (Figure 57) although the disposition of the fourth row is not clear. Oral styles appear to begin as two types (Figure 57, os1, os2). The first and most prominent are 5 moderately large and distinct oral styles (os1) alternating with 4 smaller, less distinct oral styles (os2). The middorsal os2 style is missing.

J-2 Stage: The second stage (Figures 47, 48) of juvenile development is represented by a specimen 205 μm long (RH 1661.26, USNM 235460). Its estimated standard width is 34 μm, the SW/TL 16.5 percent. Middorsal spines (Figure 48) are present on segment 6 (30 μm long), segment 8 (40 μm long), segment 10 (36 μm long), segment 11 (56 μm long), and a newly added segment 12 (132 μm long; the midterminal spine is 146 μm long, 71.2 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (21 μm long); acicular lateral spines are on segment 10 (22 μm long) with cuspidate lateral accessory spines (24 μm long) dorsally adjacent. Acicular lateral spines (20 μm long) are now present on segment 11 and the newly added segment 12 (49 μm long). Lateral terminal accessory spines (20 μm long) appear at the lateral margins of the terminal segment, and lateral terminal spines are represented by very small (4 μm long) protuberances mesial to the lateral terminal accessory spines. The LTS/TL is 1.9 percent, the LTAS/TL is 9.7 percent, and the LTAS/LTS is 500 percent. The cuticular scar noted in the first stage remains middorsally on segment 4. Placids are proportionally larger.

J-3 Stage: The third juvenile stage (Figures 49, 50, 60–62) is represented by a specimen 225 μm long (RH 1661.25, USNM 235460). Its estimated standard width is 37 μm, the SW/TL 16.4 percent. Middorsal spines (Figures 50, 62) are present on segment 6 (30 μm long), segment 8 (38 μm long), segment 10 (34 μm long), segment 11 (42 μm long), and segment 12 (96 μm long); although segment 13 now appears to be at least partly differentiated, there is no evidence of a middorsal spine on this segment. The midterminal spine is 170 μm long, 75.5 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (20 μm long); acicular lateral spines are on segment 10 (24 μm long) with cuspidate lateral accessory spines (22 μm long) dorsally adjacent. Acicular lateral spines (21 μm long) are present on segment 11 and cuspidate lateral accessory spines (24 μm long) have been added. Segment 12 has a single acicular lateral spine (36 μm long). Lateral terminal accessory spines (40 μm long) appear at the lateral margins of the now more distinct terminal segment; lateral terminal spines (12 μm long) are present mesial to the lateral terminal accessory spines. The LTS/TL is 5.3 percent, the LTAS/TL is 17.7 percent, and the LTAS/LTS is 333 percent. The cuticular scar (dorsal gland) noted in the first and second stages remains middorsally on segment 4. Placids are proportionately larger.

J-4 Stage: The fourth juvenile stage (Figures 51, 52) is represented by a specimen 255 μm long (RH 1661.33, USNM 235460). Its estimated standard width is 44 μm, the SW/TL 17.2 percent. Middorsal spines (Figure 52) are present on segment 6 (24 μm long), segment 8 (30 μm long), segment 10 (32 μm long), segment 11 (40 μm long), segment 12 (60 μm long), and for the first time on segment 13 (126 μm long). The midterminal spine is 116 μm long, 62.7 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (20 μm long). Acicular lateral spines are on segment 10 (20 μm long) and the adjacent cuspidate lateral accessory spines are 22 μm long. Acicular lateral spines on segment 11 (20 μm long) are accompanied by cuspidate lateral accessory spines (21 μm long). Segment 12 has a single lateral spine (30 μm long). Lateral terminal accessory spines (42 μm long) of segment 13 are dorsally adjacent to lateral terminal spines (40 μm long). The LTS/TL is 15.6 percent, the LTAS/TL is 16.4 percent, and the LTAS/LTS is 105 percent. The cuticular scar (dorsal gland) noted in the first three stages remains middorsally on segment 4. Placids are proportionately larger.

J-5 Stage: The fifth juvenile stage (Figures 53, 54) is represented by a specimen 320 μm long (RH 1661.28, USNM 235469). Its estimated standard width is 50 μm, the SW/TL 15.6 percent. Middorsal spines (Figure 54) are present on segment 6 (22 μm long), segment 8 (28 μm long), segment 10 (34 μm long), segment 11 (40 μm long), segment 12 (42 μm long), and segment 13 (76 μm long). The midterminal spine is 214 μm long, 66.8 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (20 μm long). Acicular lateral spines (20 μm long) and cuspidate lateral accessory spines (20 μm long) are on segment 10. Acicular lateral spines on segment 11 (26 μm long) are accompanied by cuspidate lateral accessory spines (23 μm long). Segment 12 has a single lateral spine (30 μm long). Lateral terminal accessory spines (60 μm long) of segment 13 are dorsally adjacent to lateral terminal spines (48 μm long). The LTS/TL is 15.0 percent, the LTAS/TL is 18.7 percent, and the LTAS/LTS is 125 percent. The cuticular scar noted in the first four stages remains middorsally on segment 4. Placids are proportionately larger.

J-6 Stage: The sixth juvenile stage or pre-adult stage (Figures 55, 56) is represented by a specimen 350 μm long (RH 1661.34, USNM 235460). Its estimated standard width is 50 μm, the SW/TL 14.2 percent. Middorsal spines (Figure 56) are present on segment 6 (22 μm long), segment 8 (33 μm long), segment 10 (39 μm long), segment 11 (41 μm long), segment 12 (42 μm long), and segment 13 (72 μm long). The midterminal spine is 210 μm long, 60.0 percent of the trunk length. Cuspidate lateral spines occur on segment 7 (21 μm long). Acicular lateral spines are on segment 10 (22 μm long) adjacent to cuspidate lateral accessory spines (26 μm long). Acicular lateral spines on segment 11 (24 μm long) are accompanied by cuspidate lateral accessory spines (24 μm long). Segment 12 has a single lateral spine 30 μm long. Lateral terminal accessory spines of segment 13 are 60 μm long, lateral terminal spines are 50 μm long. The LTS/TL is 14.2 percent, the LTAS/TL is 17.1 percent, and the LTAS/LTS is 120 percent. The cuticular scar noted in all the earlier stages is still present middorsally on segment 4. Placids remain as in the adult.

HOLOTYPE.—Adult female, TL 400 μm (Figures 1, 2, 25 26), from muddy sand, 140 m depth, 33 km east of Fort Pierce, Florida, Southeastern Atlantic Ocean. Collected 2 Aug 82 by R. Higgins, RH 1626.10, USNM 235456.

ALLOTYPE.—Adult male, TL 395 μm (Figures 3, 4), same data as for holotype, RH 1626.12, USNM 235457.

PARATYPES.—All remaining paratypes with same data as for holotype, except for dates collected and include: 15 adult males, 8 adult females, and 18 juveniles, collected 5 Apr 82, RH 1561, USNM 235451; 9 adult males, 2 adult females, and 9 juveniles, collected 5 Apr 82, RH1562, USNM 235453; 9 adult males, 8 adult females, and 3 juveniles, collected 2 Jun 82, RH 1598, USNM 235454; 11 adult males, 4 adult females, and 6 juveniles, collected 2 Aug 82, RH 1626, USNM 235455. 10 adult males, 7 adult females, and 3 juveniles, collected 4 Oct 82, RH 1630, USNM 235458; 10 adult males, 6 adult females, and 11 juveniles, collected 6 Dec 1982, RH 1653, USNM 235459; 20 adult males, 2 adult females, and 12 juveniles, collected 31 Jan 83, RH 1661, USNM 235460.