Eusarsiella nodimarginis (Darby 1965)

Eusarsiella nodimarginis 1 present paper (p. 101)

Familial Relationships

Kornicker and Sohn (1976:4) concluded that the order Myodocopida formed a monophyletic group having as a sister group the order Halocyprida containing suborders Cladocopina and Halocypridina. The character state in the sister group has been used herein to interpret directionality of character states in families within the Myodocopia.

Autapomorphic character states identify monophyletic groups but do not show relationships between the groups. The Cylindroleberididae have many autapomorphic character states, including the “baleen-comb” on the maxilla, and a flat distal comb on the fifth limb. The Cypridinidae have at least one strong autapomorphic character state: the c- and f-bristles of the adult male bear discs used by the male for grasping the female during copulation (the discs could be sense organs). The Rutidermatidae have chelalike claws on the mandible of the adult female and juveniles of both sexes (the claw on the second endopodial joint forms a pincer with the main claw of the end joint). The Sarsiellidae have a stout claw on the first endopodial joint of adult females and juveniles of both sexes. The upper lip of the Philomedidae tapers anteriorly and bears anterior tubular glandular openings in addition to more proximal lateral slit-like glandular openings. The directionality of this character state is uncertain, and the lip is not in my opinion strong evidence that the Philomedidae is a monophyletic group; however, I have assumed it to be a monophyletic group in this analysis.

Synapomorphies indicate relationships between groups. I have interpreted the following character states to be synapomorphies.

1. Strong adult sexual dimorphism of the sensory bristle of the fifth joint of the fifth antenna. This indicates a possible synapomorphy in the Cylindroleberididae, Philomedidae, Sarsiellidae, and Rutidermatidae.

2. Strong adult sexual dimorphism of the maxilla and fifth limb. This indicates a probable synapomorphy in the Philomedidae, Sarsiellidae, and Rutidermatidae.

3. Extreme reduction of the fifth joint of the first antenna of the adult male. This indicates a probable synapomorphy in the Philomedidae, Rutidermatidae, and Sarsiellidae.

4. Large tooth on second exopodial joint of fifth limb of adult females and juveniles of both sexes. This indicates a probable synapomorphy in the Philomedidae, Rutidermatidae, and in the genus Dantya of the Sarsiellidae (see below).

5. Absence of glands in the upper lip. This indicates a probable synapomorphy in the Rutidermatidae and Sarsiellidae, and possibly in some Cylindroleberididae.

6. Presence of slit-like glandular openings in the upper lip. This indicates a possible synapomorphy in the Cypridinidae and Philomedidae, but was probably a convergence.

7. Stout claw on first endopodial joint of the mandible of adult females and juveniles of both sexes. This indicates a probable synapomorphy in the subfamiles Dantyinae and Sarsiellinae. This character state is autapomorphic for the Sarsiellidae.

A classification based on only a few synapomorphies must be considered tentative. The Cylindroleberididae is a divergent type clearly separated from other familes and has been recognized as such by most investigators. If this family is excluded from the analysis, then synapomorphic character states 1, 2, 3 suggest a close relationship of the Philomedidae, Rutidermatidae, and Sarsiellidae. This relationship produces 1 convergence (character 6). In contrast, if character state 6 is considered synapomorphic it would suggest a close relationship of Cypridinidae and Philomedidae. That relationship produces 3 convergences (characters 1, 2, 3). Clearly the first relationship is parsimonious. Synapomorphic character state 5 suggests a close relationship of Rutidermatidae and Sarsiellidae. This presents no convergences except possibly in character 4. Character 4 concerns a large tooth on the fifth limb of Philomedidae and Rutidermatidae, which also is present in the genus Dantya of the Sarsiellidae. Because other genera of Sarsiellidae have only bristles on the fifth limb, they are convergent with the Cypridinidae (the cypridinids have claws not bristles). I interpret the absence of the tooth on most sarsiellids to be an apomorphic condition, having evolved after the lineage containing the genus Dantya had diverged from the Rutidermatidae. If this interpretation is correct character 4 could be an additional synapomorphy suggesting a close relationship of Philomedidae, Rutidermatidae, and Sarsiellidae.

The relationship of the Cylindroleberididae to other families is difficult to assess. Unlike members of other families it is a filter feeder and many of its appendages are adapted for that habit. Apomorphic character state 1 suggests a close relationship of Cylindroleberididae, Philomedidae, Rutidermatidae and Sarsiellidae. I could identify no synapomorphic character state showing a close relationship of the Cypridinidae, Philomedidae, Rutidermatidae, and Sarsiellidae. Therefore, I have portrayed the Philomedidae, Rutidermatidae, and Sarsiellidae as being more closely related to the Cylindroleberididae than to the Cypridinidae in the reconstructed phylogeny (Figure 113). This produces a possible convergence (character 5). Character 5 refers to the absence of glands in the upper lip. The upper lip of Cylindroleberididae has received little study and reports are conflicting. Skogsberg (1920:170) states that the Cylindroleberididae have a gland in the upper lip, whereas, Cannon (1933:758) states that labral glands in the cylindroleberidids are minute or absent.

My interpretation supports suspicions about myodocopine relationships raised previously by Poulsen (1965:483). If only Bauplane of the cylindroleberids is considered, the placement of the Cylindroleberididae and Cypridinidae on the cladogram (Figure 113) would be reversed. Inclusion of the cylindroleberids in the initial analysis would not have changed conclusions.

Based on the above considerations I propose that the 3 superfamilies established by McKenzie et al. (1983:38) comprise the following families.

Eusarsiella nodimarginis (Darby, 1965)

Sarsiella nodimarginis, Darby, 1965:33, pl. 21: figs. 1–8; pl. 22: figs. 1, 2.

HOLOTYPE.—UMMP 48803, female, carapace and appendages on 15 glass slides.

MATERIAL.—See “Station Data with Specimens Examined.”

DISTRIBUTION.—Continental shelf off North Carolina and Georgia. Collected from depth of 36 m off North Carolina and from about 30–114 m off Georgia (Figure 2, Table 1).

SUPPLEMENTARY DESCRIPTION OF ADULT FEMALE (Figure 58, 59).—Carapace with nodes along dorsal, anterior and ventral margins (about 27 total); caudal process well developed; posterior margin straight with 3 small processes; each valve with wide alar process with nodes along outer edge; area anterior and ventral to valve middle with large pits; surface of valve elsewhere smooth, unpitted (Figure 58).

Infold: Infold of caudal process with 4 small bristles (Figure 59a); additional smaller bristles on ventral infold just anterior to caudal process; posterior infold with 2 setal bristles dorsal to caudal process. (Bristles of infold difficult to see on mounted holotype.)

Size: UMMP 48803, length 1.68 mm, height 1.44 mm (from Darby, 1965:33). USNM 193108, length 1.70 mm, height including caudal process 1.62 mm, height without caudal process 1.37 mm; UMMP 48804, dry specimen, length ca. 1.2 mm.

First Antenna (Figure 59b): First joint bare. Second joint with 1 dorsal bristle with few short marginal hairs. Third and fourth joints fused; third joint with 1 short bare ventral bristle and 1 longer dorsal bristle with short marginal spines; fourth joint with 4 bristles (3 bare, ventral, 1 spinous, dorsal). Sensory bristle of fifth joint with 2 minute proximal filaments and 1 minute subterminal filament. Fused sixth joint with 1 short medial bristle near dorsal margin. Seventh joint: a-bristle about 3 times length of bristle of sixth joint with short, faint marginal spines; b-bristle bare, about twice length of a-bristle; c-bristle longer than sensory bristle of fifth joint, with 2 minute proximal filaments. Eighth joint: d- and e-bristles bare with blunt tips, both longer than b-bristle but shorter than sensory bristle of fifth joint (e-bristle slightly shorter than d-bristle); f-bristle shorter than sensory bristle, about same length as d-bristle, with minute subterminal filament; g-bristle about same length as sensory bristle, with minute subterminal filament.

Second Antenna (Figure 59c): Protopodite bare. Endopodite 1-jointed with 2 short proximal anterior bristles; distal end of joint either bare or with minute spine (holotype without terminal spine on right endopodite, and with spine on left endopodite). Exopodite: first joint with minute, medial, terminal bristle; bristle of second joint with proximal ventral spines and distal natatory hairs; bristles of joints 3–8 with natatory hairs, some with few proximal ventral spines; ninth joint with 2 bristles (1 long with natatory hairs and few proximal ventral spines, 1 short, with short marginal hairs).

Mandible (Figure 59d): Coxale endite consisting of stout spine-like process with few marginal spines. Ventral margin of coxale with slender hairs and spines. Basale: dorsal margin with 1 short bristle distal to middle and 2 short terminal bristles; 5 or 6 small bristles present near ventral margin. First endopodial joint: ventral margin with stout terminal claw; medial surface with scattered spines; dorsal margin with terminal spines forming row. Second endopodial joint: ventral margin with stout terminal claw; dorsal margin with short terminal bristle. Third endopodial joint with stout terminal claw, 1 minute dorsal bristle, and 1 minute ventral bristle.

Maxilla (Figure 59e): Typical of genus. Exopodite with 3 bristles (2 short, bare, 1 long, spinous).

Fifth Limb (Figure 59f,g): Single endite with 1 small bristle. Exopodite: first joint with 2 bristles; remaining joints fused; second joint with 3 bristles; third to fifth joints with total of 5 or 6 bristles.

Sixth Limb (Figure 59g): Single endite with 3 bristles (2 much smaller than third); end joint with 12 or 13 bristles followed by space, and then 2 stout plumose bristles.

Seventh Limb (Figure 59h): Each limb with 4 proximal bristles, 2 on each side, and 6 terminal bristles (3 on each side); each bristle with up to 6 bells. Terminus consisting of opposing combs, each with several faint teeth.

Furca (Figure 59i): Each lamella with 5 claws decreasing in length posteriorly along lamella; claw 1 fused to lamella, remaining claws separated from lamella by suture; all claws with short and long teeth along posterior margin; teeth very faint on fifth claw; several fairly stout spines on each lamella following fifth claw; spines present along anterior margin of right lamella proximal to claw 1.

Bellonci Organ (Figure 59j): Elongate, broadening distally, with rounded tip.

Eyes (Figure 59j): Lateral eyes pigmented, each with 5 ommatidia; medial eye pigmented, larger than lateral eye.

Brush-like Organ (Figure 59k): Several minute bristles present anterior to furca.

Eggs: UMMP 48803, 48804, each with 10 eggs (Darby, 1965:33). USNM 193108 with 12 eggs and small unextruded eggs.

Gut Content: Holotype with copepod in gut.