Parvimysis ornata, 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 : 18-20

Parvimysis ornata sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:2E46253A-DBDC-4CE4-8482-597EA4478E71

( Fig. 8 )

Parvimysis bahamensis, Brattegard, 1973 : fig. 14C; 1974a: 68; 1974b: 101, fig. 4F; Sorbe et al., 2007: 179.

Type material. Holotype, adult male with 2.1 mm body length ( ZMBN reg. no. 72654), paratypes 53 ♀ ad. 2.0– 2.4 mm, 52 ♂ ad. 1.8–2.7 mm, 11 subad., 11 imm., 8 juv. in vial, 1 ♀ ad. 2.7 mm, 1 ♂ ad. 2.1 mm on slides ( ZMBN 72654 ), Caribbean coast of Colombia, Bahia Granate, sta. 5071, 11°17’35’’N 74°11’30’’W, 7–8 m, sand, Ockelmann detritus sledge, 7 May 1971, leg. A. Fosshagen.

Non-types. Two samples taken with Ockelmann detritus sledge, leg. A. Fosshagen: 19 ♀ ad. 2.0– 2.4 mm, 17 ♂ ad. 1.8–2.1 mm, 10 subad., 1 imm. ( ZMBN 72669), Caribbean coast of Colombia, Burucuca, small bay N of Ro- dadero, sta. 737013, 11°12’32’’N 74°13’59’’W, 1–4 m, muddy sand, Thalassia , 1 July 1973; 14 ♀ ad. 2.0– 2.5 mm, 3 ♂ ad. 1.6–1.8 mm, 7 subad., 2 imm. ( ZMBN 72665 ), Caribbean coast of Panama, Limon Bay, S of Toro Point, outside reef flat, sta. 735291, 09°21‘34‘‘N 79°56‘50‘‘W, 2–6 m, mineral sand mixed with coarser calcareous sand, 29 May 1973 .

Type locality. Sublittoral marine waters at the Caribbean coast of Colombia, Bahia Granate, 11°17‘35‘‘N 74°11‘30‘‘W .

Derivatio nominis. The species name is a Latin adjective with female ending, referring to the lining of the telson cleft with short laminae. This name underlines the difference from the below-described P. nuda with smooth telson cleft.

Diagnosis. Parvimysis with obtuse-angled rostrum, anterior margin broadly rounded. Freely projecting portion of the rostrum 0.5–0.6 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 1.8–2.1 times the length of the terminal segment of the antennular trunk in dorsal view. Antennular trunk extending beyond trunk of antennal flagellum and mostly beyond proximal segment of antennal scale. Apical segment of antennal scale extending by about its half to full length beyond trunk of antennal flagellum. 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 12–17% of total palp length. Median segment with only two setae in subterminal position on inner margin, more proximal portions of this segment with 1–0 seta on inner margin (as in Fig. 3G , if present), none on outer margin. Maxillary palp with proximal segment 0.2–0.3 times total palp length. Exopod of maxilla extends shortly beyond middle of the terminal segment of the palpus. Thoracic exopods 2–7 with 9-segmented flagellum. Endopods 1, 2 without claw; endopods 3–8 with moderately strong, slightly curved claw. Length of claw 5 is 7–9 times its width at basis. Endopods 3–8 with oblique articulation between carpus and propodus. Carpus of endopod 5 with comb-like series of setae on inner margin in males, normal setation in females. 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 0.5–0.6 times the length of the median segment. Scutellum paracaudale broadly rounded. Telson short, length 2.9–4.3 times distance between the latero-terminal spines. Shape roughly trapezoid; lateral margins slightly sinusoid, tapering, each armed with four short spines; each lateral margin ending in a latero-terminal lobe with apical spine, the latter clearly longer than the lateral spines. Telson terminally emarginate by 15–19% its length; emargination proximally angular to well rounded. Margins of the (sub)triangular cleft lined along most of their extension by a total of 6–10 laminae-denticles with 0.1–0.4 times length of latero-apical spines; cleft without spines.

Description. All features of the diagnosis and those reported further above as common to the six Caribbean species of the present study. Size of adults from Colombia is 1.8–2.7 mm (n = 75) in males, 2.0– 2.4 mm (n = 80) in females.

Cephalic region ( Fig. 8 A–F). Cornea dorsoventrally weakly compressed, calotte-shaped in dorsal, oviform in lateral view, length 1.3–1.8 times height in lateral view ( Fig. 8B ). Basal segment of antennular trunk about equal to combined median and apical segments in both sexes.Antennal scale with apical segment 26–32% length of the basal segment. Third segment of the trunk of the antennal flagellum with 61–79% length of the second segment. Apical segment of mandibular palp with 1–2 smooth setae, 5–6 modified setae bilaterally bearing series of stiff, spine-like barbs; and one longer seta with barbs along most of its distal 40–50%. Basal segment of maxillary palp with three barbed setae on inner margin, apical segment densely setose at tip and on terminal 30–40% 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. 8E ) on mid-posterior part of lateralia; this spine with total of 11–18 teeth, among which 2–4 large teeth at tip. Group of four centro-apically serrated spines in even more posterior position on lateralia; the largest, most proximal spine ( Fig. 8F ) with total of 7–10 small teeth distributed over apical 60–70% of spine length.

Thorax ( Fig. 8 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. Exopod 1 with 8-segmented flagellum, exopod 8 with (8–7)-segmented flagellum in females, (8–9)-segmented in males. Thoracic endopod 8 slender; when stretched, extending forwards shortly beyond the eyes or backwards to the end of pleonite 6. Dactylus of endopod 2 large, equipped with 6–9 modified setae (as in Fig. 4B ) plus a few smooth setae, no spine-like setae. Length and slenderness of claws not clearly different among endopods 3–8; claw 3 is 8–9 times its width at basis, this relationship 7–9 in claw 8. Penes terminally with 4–11 minute setae facing the ejaculatory opening.

Pleon ( Fig. 8 M–R). Male pleopod 5 slender, 1.4–1.7 times length of pleopod 3. Male pleopod 4, when stretched, reaching to end of pleonite 5, its large apical seta ends to 60–80% length of pleonite 6. Fourth endopod 0.8–1.1 times length of basal segment of exopod; endopod with 8–9 barbed setae. Uropods with endopod 0.8–1.0 times length of exopod or 1.6–1.8 times length of telson (without spines). Length of exopod 6–7 times maximum width. Telson length 1.1–1.3 times its width at basis, or 0.5–0.6 times length of exopod of uropods, or 0.7–0.9 times pleonite 6. Laminae-denticles with 0.2–0.4 times median length of lateral spines.

Distribution. Sublittoral marine waters at the Caribbean coasts of Panama, Colombia and Venezuela. Sorbe et al. (2007) reported these mysids as P. bahamensis from fine soft sediments and sandy substrates in 1–25 m depth, in part with Thalassia , also from soft, organic silt beneath roots of mangrove trees.

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 3. Parvimysis laminata sp. nov. from Curaçao, holotype male with body length 2.7 mm (A, B), paratypes female 2.6 mm (C, G), 3.2 mm (D, E, J), 2.1 mm (F, H), 2.7 mm (K); A, anterior body region of male (setae omitted from antennal scale), detail (B) shows right eye in lateral view; C, carapace expanded on slide; D, female antennula, dorsal aspect; E, antenna, ventral; F, labrum; G, mandibles, caudal; H, labium; J, maxillula, caudal; K, maxilla, caudal.

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 8. Parvimysis ornata sp. nov. from Colombia (A–D, G–O, Q) and Panama (E, F, P, R); holotype, adult male with body length 2.1 mm (A, B, O), paratypes male 2.1 mm (C, G, J–M), females 2.7 mm (D, H, N), 2.9 mm (Q), non-type females 2.3 mm (E, F, P), 2.5 mm (R). 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, R, telson variants.