Neonesidea Maddocks, 1969

Maddocks, Rosalie F., 2021, Taxonomic applications of the esophageal flapper valve in the Genus Neonesidea (Bairdioidea, Podocopida, Ostracoda), including descriptions of new and poorly known species from the Caribbean and Gulf of Mexico, Zootaxa 4903 (4), pp. 451-492 : 454-455

Genus Neonesidea Maddocks, 1969

1969 Neonesidea Maddocks : 16.

1972 Neonesidea Maddocks—Danielopol , p. 42.

1995 Neonesidea Maddocks—Maddocks , p.199.

2013 Neonesidea Maddocks—Maddocks , p. 466.

Supplemental Description. The carapace (ex., Fig. 11 I–M) is more or less fusiform with smoothly curving lateral and dorsal outlines. The two valves are almost the same size, with only minimal LV overlap. Females are longer than males and may be higher in proportion to length. The LV and RV have nearly equal size and fairly similar outlines. As always in Bairdiidae , the LV has more rounded contours with some dorsal overreach and a nearly level or convex ventral margin, while the inserting RV necessarily has more marked dorsal angles and a more pronounced ventral indentation.

The surface is smooth or undulating, never punctate. The posteroventral angle is subacute and sharply marked. In each valve, the margin just above the posteroventral angle is subtly flared or caudate (ex., Figs. 11 N–P). The posterodorsal caudal gape is protected on each valve by a row of enlarged, fan-shaped, plumose setae (ex., Figs. 16L ), which rise from enlarged, slightly elevated pores near (not at) the valve edge. The LV typically has numerous small, tapering, slightly curved posteroventral marginal denticles (ex., Fig. 4I ), and the posteroventral angle may be prolonged by a larger spine (ex., Fig. 11 N–P). Anteroventral marginal denticles, if present, are less conspicuous. The RV may have narrow anteroventral and posteroventral marginal frills (ex., Fig. 4J ). Simple NPC of many sizes, mostly without walls and furnished with simple sensilla, are numerous (ex., Figs. 13D ). The patch pattern always includes a central opaque spot, and smaller, less clearly defined opaque spots may be present at the anterior, anterodorsal, posterodorsal and/or posterior angles (ex., Figs. 11 J–M).

The plate of the esophageal flapper valve is wedge-shaped in dorsal profile with slightly bowed to nearly straight sides. In typical species, the curved posterior margin carries about 6 to 10 low, conical to mound-like teeth, arranged symmetrically on either side of a narrow medial gap. Because these teeth project diagonally upward (dorsally) as well as outward (posteriorly), the zigzag silhouette in photographs varies according to the tilt of the plate and viewing angle (ex., Figs. 12 F–G, I–H, and N–O are all views of the same specimen). Their profiles range from triangular to rounded-conical to low mounds. Usually, the largest teeth are medial, and their size decreases laterally. A lateral gap, containing no teeth or tiny, irregular teeth, separates the posterior teeth from a prominent, compound or multilobate corner tooth. This configuration is typical for species of the N. schulzi and N. tenera species-groups (informal).

A different configuration is seen in species of the N. dinochelata species-group (informal), in which the plate has no teeth at all (ex., Figs. 6B, C, I ; 7 L–M, U–V). The posterior perimeter curves smoothly on either side of a narrow medial gap, producing two broad lobes. A variant form has four broad lobes separated by small clefts (ex., Fig. 3C ). Rather broad lateral gaps separate the central lobes from asymmetrical, horn-shaped extensions (winglets) at the corners. The posterior margin of the plate may be smooth or edged with very short, discontinuous lamellae, and it may be emphasized by a darker stripe.

Remarks. The key character uniting species into the Genus Neonesidea is the bifid hook of the distal claw of the adult male antenna (ex., Figs. 13A , 16B ). Slight variations in the shape of this hook have been noticed, but in the current state of our knowledge they do not contribute reliably to diagnosis of species. Some apparent differences in shape of the hook may result from damage or viewing angle, while others may be related to the overall proportions of the limb. Unfortunately, this hook is thin, not heavily sclerotized, and carried on the flexibly-jointed terminal podomere of the A2. This terminal podomere and claw are nearly always missing from the dry fragments, which are occasionally retained within subfossil carapaces of individuals that were living at the time of collection. Females have a tapered terminal claw without any hook (ex., Fig. 15D ), and the dimorphic accessory seta is long (vs. short in males); unfortunately this seta is thin and unlikely to be recognizable in dried specimens.

Maddocks (1995) erroneously described several species of Neonesidea as “punctate.” Puncta are incised circular depressions that do not penetrate the carapace like NPC. Puncta are not present in Neonesidea . The uneven or undulating texture of the valve surface in some Neonesidea is an artifact of the closely spaced NPC (ex., Fig. 8O ).

Species-Groups. Maddocks (1969, p. 20) suggested that informal species-groups may be recognized within the genus Neonesidea , three of which were tentatively designated as the N. schulzi , N. tenera and N. dinochelata species-groups. The species of each group share general resemblances in carapace shape, proportions and sensilla. The first two groups have basically the same configuration of the esophageal flapper valve, while the third has a more reduced presentation. Corresponding distinctions in the A2, hemipenes, and other soft parts remain elusive, however. A few other species do not adhere to any of these groups, or, indeed, to each other. At present, it is best to treat these species-groups as informal generalizations rather than taxonomic categories.

The 17 species described below are listed in alphabetical order. They may be assigned tentatively to informal species-groups as follows: To the N. schulzi species-group: N. caraionae n. sp., N. gerda , N. holdeni (?), N. longisetosa , N. omnivaga , N. schulzi . To the N. tenera species-group: N. decipiens , N. manningi , N. mediterranea , N. plumulosa , N. tenera . To the N. dinochelata species-group: N. bacata , N. credibilis n. sp., N. dinochelata , N. sp. aff. N. dinochelata , N. edentulata , N. florea n. sp.

Figures

FIGURE 3. Neonesidea credibilis n. sp.; A–H, holotype specimen 500M from Anton Bruun station 412C; I–N, subfossil specimens from Nosy Be: I, 4064RV, J, N, 4062LV; K–M, 4063LV. Neonesidea schulzi (Hartmann), O–Q, specimen 458F from Admirante Island.A, RV exterior in TL; B, DV of EV with ring, plate and bracket; C, DV of plate; D, A2 claw; E, right hemipenis; F, both hemipenes and fragmentary furcae; G–H, AMS and NPC of RV at high and low focus; I–L, RV and LV exteriors in TL; M–N, AMS and NPC of RV and LV; O, DV of EV with ring, plate and bracket; P, plumose sensilla of posterior margin of LV; Q, LV exterior in TL. Scale bar = 50 µm.

FIGURE 4. A–G, Neonesidea decipiens (M̹ller), specimen 170F; H–N, Neonesidea mediterranea (M̹ller), specimen 171F. A–B, RV and LV exteriors in TL; C–D, RV and LV exteriors in RL; E, AMS and NPC of RV; F, VV of EV with ring, plate, bracket and both braces; G, marginal teeth of plate; H, A2 claw; I, posteroventral denticles of LV; J, posteroventral frill of RV; K–L, DV of EV with plate, bracket and braces; M–N, RV and LV exteriors in TL. Scale bar = 50 µm.

FIGURE 6. Neonesidea florea n. sp. A–H, specimen 974M; I–R, specimen 977M; both from West Flower Garden. A, A2 claw; B, DV of plate edge; C, DV of EV with ring, plate, bracket and braces; D–E, right and left hemipenis and furca; F, distal end of hemipenis, with tip of copulatory tube and forked aesthetasc; I, DV of EV with ring, plate, bracket and braces; J, DV of compressed head capsule, including EV with ring, plate, bracket, and braces, as well as mouth region (lower left) and basal podomeres of A2 (lower right); K, hemipenis with zygum; L, hemipenis; M–N, RV and LV exteriors in TL; O–P, RV and LV exteriors in RL; Q–R, AMS and NPC of RV and LV. Scale bar = 50 µm.

FIGURE 7. Neonesidea florea n. sp. A–D, specimen 4073W, from Belize; E–S, 975M; T–V, specimen 977J; both from West Flower Garden. A–B, E–F, RV and LV exteriors in TL; C–D, G–H, AMS and NPC of RV and LV; I–J, RV and LV exteriors in RL; K–L, M, DV of plate and bracket; N, zygum, hemipenis and furca; O, A2 claw; P–R, hemipenes; S, brace; T, A2 claw of immature female; U–V, DV of EV with ring, plate and bracket. Scale bar = 50 µm.

FIGURE 8. A–L, Neonesidea florea n. sp. A–F, specimen 975M; G, specimen 1174LV; H–L, specimen 974M; all from West Flower Garden. M–R, Neonesidea gerda (Benson and Coleman); M, specimen 1252RV; N–O, specimen 1253LV; both from West Flower Garden; P, specimen 2847RV; Q–R, specimen 2848LV; both from the Bay of Campeche. A–B, E–F, P–R, in TL; C–D, in RL; G–O, by SEM. A–B, exteriors of RV and LV; C–D, DV of RV and LV; E–F, AMS and NPC of RV and LV; G, interior of LV; H–I, exteriors of RV and LV; J–L, NPC and sensilla; M–N, exteriors of RV and LV; O, NPC of LV; P, R, exteriors of RV and LV; Q, AMS of LV. Scale bar = 50 µm.

FIGURE 11. Neonesidea gerda (Benson and Coleman); A–D, specimen 2397F, from SW Florida; E–G, 4041W; H, specimen 4043W; both from Florida Keys. Neonesidea longisetosa (Brady); I, specimen 4046W; J–P, specimen 4045M; both from Belize. A–B, fragmentary RV and LV exteriors in TL; C, posteroventral flange and sensilla of RV; D, posteroventral marginal denticles and sensilla of LV, but no terminal spine is visible; E–F, RV exterior in TL; G, interior of RV in RL, with fragments of dry appendages and two food balls (f) in domicilium; H–I, DV in RL; J–K, interiors of LV and RV in RL, with fragments of appendages (brown) and two food balls (f); L–M, RV and LV exteriors in TL with fragments of appendages (brown) and two food balls (f); N, posteroventral fringe and terminal spine of RV in TL, with dry food ball (f), hemipenis (h), plate of EV (p), and limb fragments; O, posteroventral region of LV, with marginal denticles, opaque spot, and food ball (f), but no terminal spine is visible; P, interior of posterior region of RV in TL, after removing food ball, showing terminal spine, hemipenis (h), and a limb fragment. Scale bar = 50 µm.

FIGURE 12. Neonesidea longisetosa (Brady). A–O, subfossil specimen 4045M from Belize; P–Q, specimen 1652M from the Bahamas; S, subfossil specimen 4053W from Jamaica. A. A–D, hemipenis, with distal details; E, corner tooth of plate; F–G, VV of plate at high and low focus; H, interior of posteroventral region of RV, showing dry fragments of plate and ring; I–L, diagonal view of plate standing upright within RV interior, from high focus to low focus; M–N, edge view of posterior margin of same plate after removal from valve, showing pyramidal teeth and row of ventral setules, the dorsal surface is up (concave); P–R, hemipenis, with distal details; S, VV of EV with ring and plate. Scale bar = 50 µm.

FIGURE 13. A–F, Neonesidea manningi Maddocks; A, specimen 895M; B–C, specimen 903F; D–E, specimen 900M; F, specimen 906J; all from Ascension Island. G–I, Neonesidea plumulosa Maddocks, holotype specimen 3960M, from French Frigate Shoal, the Hawaiian Islands. J–M, Neonesidea tenera (Brady); J, specimen 3906M; K, specimen 3892F; L, specimen 3905F; M, specimen 3957J; all from French Frigate Shoal, the Hawaiian Islands. A–B, antennal claws; C–G, I, L, EV with ring, plate, bracket, braces, and details of posterior teeth of plate; H, right lateral view of carapace in RL; M, left lateral view of soft body within decalcified RV. Scale bar = 50 µm.

FIGURE 15. Neonesidea omnivaga Maddocks. A–E, specimen 2444F; F–L, specimen 2447W. A–B, RV and LV exteriors in TL; C, AMS of LV; D, A2 claw; E, genital lobe; F–G, AMS of RV and LV; H–I, RV and LV exteriors in TL with food ball (f) and unidentifiable fragments of appendages.

FIGURE 16. Neonesidea schulzi (Hartmann). A–G, specimen 013M; images scanned from contact paper print from over-exposed negative film of over-stained preparation, taken in 1967; magnifications were not recorded. H–I, specimen 767W; J–K, specimen 768F; L, specimen 3080F. A, lateral view of compressed head capsule with EV, showing forehead, atrium, labrum, esophagus, chitinous struts, and EV with ring, plate, and braces; B, A2 claw; C, lateral view of both hemipenes, folded; D–E, DV of both hemipenes and zygum; F–G, EV and plate; H–K, RV and LV exteriors in TL; L, posterior spine of LV and fan-shaped plumose sensilla, by SEM. Scale bar = 50 µm.