Parvimysis nuda, Wittmann, 2020

Wittmann, Karl J., 2020, Revision of the genus Parvimysis (Mysida, Mysidae) with descriptions of five new species from coastal waters of the Caribbean, Zootaxa 4742 (1), pp. 1-30 : 20-22

Parvimysis nuda sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:E37DAB99-BAA7-4A84-9316-E260FCD58C15

( Fig. 9 )

Parvi mysis bahamensis Brattegard, 1969 : part of paratypes from station 37–67.

Type material. Holotype, adult male with 2.1 mm body length ( ZMBN reg. no. 73149), paratypes 164 ♀ ad. 2.2–3.0 mm, 241 ♂ ad. 1.5–2.8 mm, 92 subad., 153 imm., 59 juv. in vial, 1 ♀ ad. 2.6 mm, 1 ♂ ad. 2.3 mm on slides ( ZMBN 73149 ), stn. 37–67 (6172), Bahamas, Eleuthera, Pelican Cay, outside James Cistern , 25°16’45’’N 76°20’20’’W, 7 m, sand and coral heads, Ockelmann detritus sledge, 22 April 1967, leg. Torleiv Brattegard.

Non-types (in present definition). 4 ♀ ad. 2.3–2.6 mm, 1 ♂ ad. 2.3 mm ( AMNH IZC 331513), originally la- beled as paratypes of P. bahamensis , from same sample as for the holotype of P. nuda sp. nov.

Type locality. Known only from sublittoral marine waters of Bahamas, Eleuthera, Pelican Cay , 25°16‘45‘‘N 76°20‘20‘‘W .

Derivatio nominis. The species name is a Latin adjective with female ending, referring to the naked (= smooth) margin of the telson cleft, in order to underline the difference from P. ornata where the cleft is lined by small laminae-denticles.

Diagnosis. Parvimysis with obtuse-angled rostrum, tip broadly rounded. Freely projecting portion of the rostrum 0.3–0.4 times the length of the terminal segment of the antennular trunk. Antero-lateral edges of the carapace produced into a short acute process. Eyes moderately large; maximum diameter of cornea 1.7–2.0 times the length of the terminal segment of the antennular trunk in dorsal view. Antennular trunk slightly extending beyond trunk of antennal flagellum or ending at about same height. Apical segment of antennal scale extending about full length beyond trunk of antennal flagellum, basal segment not extending beyond antennular trunk. Cardiac portion of foregut with simple, smooth spines; additional stout, modified spines on lateralia, not so on dorso-lateral infolding. Mandibular palp with apical segment making up 14–17% of total palp length. Median segment subterminally with two basally barbed setae on inner margin; remaining portions of this segment smooth. Maxillary palp with proximal segment 0.3 times total palp length. Exopod of maxilla extends shortly beyond middle of the terminal segment of the palpus. Thoracic exopods 2–7 with 8–segmented flagellum. Endopods 1, 2 without claw; endopods 3–8 with moderately strong to slender, weakly curved claw. Length of claw 5 is 7–12 times its width at basis. Endopods 3–8 with oblique articulation between carpus and propodus. Carpus of endopod 5 with normal setation in both sexes. Oostegites normal. Exopod of fourth male pleopod 3-segmented, ending in large modified seta plus a minute lobe with minute seta (similar to Fig. 1N ). Apical segment of exopod is 0.3–0.5 times the length of the median segment. Scutellum paracaudale triangular with narrowly to widely rounded tip. Telson short, length 3.6–4.7 times distance between the latero-terminal spines. Shape roughly trapezoid; lateral margins slightly sinusoid, tapering, each armed with 2–3 short spines; each lateral margin ending in latero-terminal lobe with apical spine, the latter longer than the lateral spines. Telson terminally emarginate by 11–26% its length; emargination proximally well rounded, showing smooth margins only.

Description of types. All features of the diagnosis and those reported further above as common to the six Caribbean species of the present study. Size of adult males 1.5–2.8 mm (n = 242), females 2.2–3.0 mm (n = 164).

Cephalic region ( Fig. 9 A–F). Cornea dorsoventrally weakly compressed, calotte-shaped in dorsal, oviform in lateral view, length 1.4–1.7 times height in lateral view ( Fig. 9B ). Basal segment of antennular trunk about equal to combined median and apical segments in both sexes.Antennal scale with apical segment 27–31% length of the basal segment. Third segment of the trunk of the antennal flagellum with 74–80% length of the second segment. Apical segment of mandibular palp with two smooth setae, 4–6 modified setae bilaterally bearing series of stiff, spine-like barbs; and one longer seta with barbs along most of its distal 40–70%. Basal segment of maxillary palp with three barbed setae on inner margin, apical segment densely setose at tip and on terminal 30–50% of inner margin, whereas lined by small hairs in more proximal portions. Each half of the foregut with one large, apically pronged, serrated spine ( Fig. 9E ) on mid-posterior part of lateralia; this spine with total of 10–16 teeth, among which 2–4 large teeth at tip. Group of 3–4 centro-apically serrated spines in even more posterior position on lateralia; the largest, most proximal spine ( Fig. 9F ) with total of 10–15 small teeth distributed over apical 60–80% of spine length.

Thorax ( Figs 9C , G–L). Length increases from exopod 1 to (5–6) and decreases from 6 to 8; length of endopods increases from 1 to 8. Basal plate of thoracic exopods 1–8 well rounded. Flagellum 7-segmented in exopod 1 versus (8–7)-segmented in exopod 8. Thoracic endopod 8 slender; when stretched, extending forwards to the eyes or backwards to the end of pleonite 6. Dactylus of endopod 2 large, equipped with 6–7 modified setae (as in Fig. 4B ) plus a few smooth setae, no spine-like setae. Length of claws increases in series of thoracic endopods 3–5, not clearly in more caudal endopods. Slenderness of claws not clearly different among endopods 3–8; claw 3 is 8–11 times its width at basis, this relationship 9–10 in claw 8. Penes terminally with 7–10 minute setae facing the ejaculatory opening.

Pleon ( Fig. 9 M–Q). Male pleopod 5 slender, 1.2–1.8 times length of pleopod 3. Male pleopod 4, when stretched, reaching to end of pleonite 5, its large apical seta ends at the middle of pleonite 6. Fourth endopod 0.8–1.1 times length of basal segment of exopod; endopod with 8–11 barbed setae. Uropods with endopod 0.9–1.0 times length of exopod or 1.4–1.7 times length of telson (without spines). Length of exopod 7–8 times maximum width. Telson length 1.3–1.7 times width at basis, or 0.5–0.6 times length of exopod of uropods, or 0.7–0.9 times pleonite 6.

Figures

FIGURE 1. Parvimysis bahamensis Brattegard, 1969, from the Bahamas, non-types: adult males with body length 2.3 mm (A–C, J, K, P), 2.1 mm (F, G, L–N, R), and females with 2.3 mm (D), 2.6 mm (E, O), 2.4 mm (H), 2.8 mm (Q); A, anterior body region of male, dorsal aspect (setae omitted from antennal scale), detail (B) shows left eye in lateral view; C, carapace expanded on slide; D, female antennula, dorsal; E, apically pronged, serrated spine from lateralia in the foregut; F, centro-apically serrated spine from posterior part of the lateralia; G, dactylus of thoracic endopod 3; H–K, thoracic endopod 5 in female (H) and male (J), detail (K) shows dactylus; L, dactylus of thoracic endopod 8; M, male pleopod 4, detail (N) shows tip of exopod; O, female pleopod 5; P, Q, variants of the scutellum paracaudale, lateral; R, telson.

FIGURE 4. Thoracopods 1–7 in Parvimysis laminata sp. nov. from Curaçao, paratypes female with body length 2.5 mm (A), 3.2 mm (B, H), 2.9 mm (C, D), 3.1 mm (J), 3.0 mm (K), and males 2.8 mm (E), 2.5 mm (F, G); A, thoracopod 1 with sternites 1–4; B, endopod 2; C, endopod 3, detail (D) shows dactylus; E, endopod 4; F–H, endopod 5 in female (F) and male (G), detail (H) shows dactylus; J, endopod 6; K, endopod 7 with oostegite.

FIGURE 9. Parvimysis nuda sp. nov. from the Bahamas, holotype adult male with body length 2.1 mm (A, B, O), paratypes males 2.5 mm (C, E, F, M), 2.3 mm (G, J, L), another male 2.3 mm (K), and female 2.6 mm (D, H, N, P, Q); A, anterior body region of male, dorsal aspect (setae omitted from antennal scale), detail (B) shows right eye in lateral view; C, carapace expanded on slide; D, female antennula, dorsal; E, apically pronged, serrated spine from lateralia in foregut; F, centro-apically serrated spine from posterior part of lateralia; G, dactylus of thoracic endopod 3; H–K, thoracic endopod 5 in female (H) and male (J), detail (K) shows dactylus; L, dactylus of thoracic endopod 8; M, male pleopod 4; N, female pleopod 5; O, P, variants of scutellum paracaudale, lateral; Q, telson.