Hippolyte longiallex, Cédric, 2007

Cédric, 2007, New records of Atlantic Hippolyte, with the description of two new species, and a key to all Atlantic and Mediterranean species (Crustacea, Decapoda, Caridea), Zoosystema 29 (1), pp. 183-207 : 193-196

publication ID	https://doi.org/ 10.5281/zenodo.5397868
persistent identifier	https://treatment.plazi.org/id/03E4113B-FFED-FF68-FF7E-FC3CFB815396
treatment provided by	Marcus
scientific name	Hippolyte longiallex
status	sp. nov.

Treatment

Hippolyte longiallex View in CoL n. sp.

( Figs 7-9 View FIG View FIG View FIG )

TYPE MATERIAL. — West AFrica. Gulf of Guinea, Principe Island, Pedra da Galé , 1°43’N, 7°23’E, 35 m depth, from blue Muriceopsis tuberculata (Esper, 1792) , scuba diving, 16.II.2004, coll. Peter Wirtz, 2 ovigerous ♀♀ (holotype with intact rostrum [MNHN-Na16262]; paratype with broken rostrum [MNHN-Na16263]; all P3-P5 are detached and cannot be attributed to which specimen) (MNHN-Na16263). — Principe Island, Pedra da Galé, 1°43’N, 7°23’E, 35 m depth, from red M. tuberculata , scuba diving, 16.II.2004, coll. Peter Wirtz, 1 ovigerous ♀ paratype (MNHN-Na16264). — Pedra da Galé, 40 m depth, from M. tuberculata , scuba diving, 17.II.2004, coll. Peter Wirtz, 1 paratype ♀ with a bopyrid in gill chamber (MNHN-Na16265). São Tomé Island, Diogo Vaz, 35 m, from gorgonians, scuba diving, 13.II.2006, coll. Peter Wirtz, 1 paratype ♀ (MNHN-Na16266) GoogleMaps .

ETYMOLOGY. — The name derives from the Latin adjective longus (long) and noun allex (big toe), the name alluding to the very long terminal unguis of the P3-P5. The name is a noun in apposition.

DISTRIBUTION. — Tropical West Africa: Principe and São Tomé islands.

DESCRIPTION

Carapace stout. Rostrum narrow, straight, slightly shorter than carapace, shorter or longer than antennular peduncle. Rostrum without postrostral tooth, with two or three dorsal teeth (of which one is close to rostrum tip); one or two ventral teeth, close to tip of rostrum ( Fig. 7 View FIG A-C). Hepatic tooth not reaching anterior edge of carapace. Pterygostomial angle barely protruding.

Third pleonite with a well distinct curve in lateral view. Ratio dorsal length/height of sixth pleonite: 2.5 in holotype ( Fig. 7A View FIG ). Distal border of telson with four large and eight short spines in dissected paratype ( Fig. 7I View FIG ). First pair of dorsolateral spines on 0.5 of telson and second pair on 0.7 ( Fig. 7H View FIG ).

Unpigmented part of cornea scarcely longer than broad ( Fig. 7D View FIG ). Cornea not reaching stylocerite apex ( Fig. 7A View FIG ). First article of antennular peduncle without distolateral tooth; stylocerite short, reaching 0.67 of first article of antennular peduncle ( Fig. 7E View FIG ). Second article of antennular peduncle slightly longer than broad in dorsal view, distinctly longer than third article in dorsal view. Inner antennular flagellum incomplete or missing in all specimens. Scaphocerite 3.1-3.3 times as long as wide; distolateral spine of scaphocerite not reaching tip of blade; distolateral spine and blade separated by a distinct notch ( Fig. 7F View FIG ).

Mouthparts with morphology typical for the genus Hippolyte ( Figs 7G View FIG ; 8 View FIG ). Mandibular incisor process with five teeth ( Fig. 8A View FIG ). Third maxilliped reaching about 0.5 of scaphocerite ( Fig. 7A View FIG ). Ultimate article of third maxilliped with few rather short apical setae, with eight rather slender conical spines on its apex and the distal third of its mesial border; 4.2 times as long as wide when dorsally measured; 1.9 times as long as penultimate; exopod of third maxilliped not reaching half of antepenultimate segment of endopod ( Fig. 7G View FIG ).

P1 ( Fig. 9A View FIG ) with outer edges of fingers of chela not denticulate.

P2 ( Fig. 9B View FIG ) with first segment of carpus 1.5 times as long as third segment, 0.95 times as long as second and third segments combined; first segment 3.6 times as long as wide; second segment 1.1 times as long as wide; third segment 1.6 times as long as wide.

P3-P5 slender ( Fig. 9 View FIG C-G). Merus and carpus of P3-P5 without spines; propodus with about two or three tiny spinules on distal third, with few setae; dactylus long, very slender with a single huge terminal spine (0.4 times as long as the whole dactylus, unguis included), with two or three slender and very short spines on flexor border. Dactylus of P3 about 0.85 times as long as carpus. Last two spines of flexor border of P3-P5 about as long as or longer than width of dactylus at the level of insertion of terminal spine.

No specimens with plumose setae on body (“fascigerous” specimens) were recorded.

Colour pattern

Unknown.

Size

Total length up to 8 mm.

ECOLOGY

Commensal of the gorgonian Muriceopsis tuberculata , between 35 and 40 m depth.

REMARKS

Hippolyte longiallex n. sp. has unusually stout eyestalks, with a swollen non-corneal part. The rostrum of some specimens of H. longiallex n. sp. is reminiscent of that of H. varians . However H. longiallex n. sp. is unusual in the genus Hippolyte by the morphology of its ambulatory pereiopods. The merus has no lateral or ventral spine, whilst at least the third pair (and usually also the fourth one and often the fifth one) have one or more spines in other species. The carpus of the third pereiopod has no spine, whilst all other known species except H. nicholsoni have an outer carpal spine. The dactylus of the last three pereiopods is characterized by its slenderness and especially by its single terminal unguis which is no less than 0.4 times as long as the whole dactylus. In other Hippolyte species except H. nicholsoni , there are two or more terminal spines on the dactylus, which are about 0.15 times as long as as the whole dactylus. Hippolyte longiallex n. sp. is probably the sister species of the West Atlantic H. nicholsoni , which is also a gorgonian associate.

Adult females of the two species can be separated as follows. Hippolyte longiallex n. sp. has no spine on the merus of the third pereiopod ( Fig. 9A View FIG ), whilst H. nicholsoni has one subdistal spine ( Fig. 10D View FIG ). In H. longiallex n. sp., the dactylus of the third pereiopod is 0.85 times as long as carpus ( Fig. 9A View FIG ), whilst in H. nicholsoni it is 0.50 times as long ( Fig. 10D View FIG ). The dactylus of H. longiallex n. sp. is also more slender than that of H. nicholsoni ( Fig. 9A View FIG vs. Fig. 10D View FIG ). In H. longiallex n. sp., the last two spines of flexor border of P3-P5 are about as long as, or longer than width of dactylus at the level of insertion of distal unguis ( Fig. 9B, D View FIG ), whilst in H. nicholsoni these spines are no more than 0.25 times as long as width of dactylus at the level of insertion of distal unguis ( Fig. 10E View FIG ). In H. longiallex n. sp. the rostrum has one to three dorsal teeth, at least one of them being far beyond the middle of rostrum ( Fig. 7 View FIG A-C), whilst in H. nicholsoni there are zero or one (very rarely two, according to Chace [1972]) dorsal teeth, and if one tooth is present, it is on the middle of rostrum ( Fig. 10 View FIG A-C). With a maximum recorded size of 8 mm, H. longiallex n. sp. is by far the smallest known Hippolyte species.

Hippolyte nicholsoni Chace, 1972 View in CoL ( Fig. 10 View FIG )

Hippolyte nicholsoni Chace, 1972: 113 View in CoL , figs 46, 47. — Abele & Kim 1986: 231 (key), fig. d-h p. 237 (after Chace 1972). — Debelius 1999: 14, unnumbered colour photograph. — Wicksten 2005: 112, fig. 11 (after Chace 1972).

DISTRIBUTION.— West Indies: British Virgin Islands, Antigua Island, Saint Lucia Island, Tobago; Yucatán, Honduras.

MATERIAL EXAMINED. — Honduras. Pelican Point, Cayos Grande, Cayos Cochinos, from a Pseudopterogorgia americana (Gmelin, 1791) , 4.6-16.7 m depth, VII.2003, leg M. Dowell & D. Livingston, 8 ♀♀ ( OUMNH Zoo. Coll. 2004-17-0002).

British West Indies. Pine Cay, Turks and Caicos Islands, near 21°51’N, 72°05’W, from P. americana , 3 m depth, 5.XI.1988, coll. Stephen Spotte, 5 ♂♂, 1 ovigerous ♀ (MNHN-Na16267).

REMARKS

Chace (1972) states that in adult females the rostrum is usually dorsally unarmed, rarely with one or two dorsal teeth. The Honduran material examined comprises females with an unarmed rostrum and with one dorsal tooth in similar proportions. The British West Indian female and males have the rostrum dorsally (and ventrally) unarmed.