Hippolyte cedrici, Fransen & Grave, 2019

Fransen, Charles H. J. M. & Grave, Sammy De, 2019, Two new species of Hippolyte from the Tropical Central and East Atlantic (Crustacea, Decapoda, Caridea), Zootaxa 4550 (2), pp. 201-220 : 202-210

publication ID	https://doi.org/ 10.11646/zootaxa.4550.2.3
publication LSID	lsid:zoobank.org:pub:F4EB690C-E509-4C00-94BA-093D5FF2E355
DOI	https://doi.org/10.5281/zenodo.5933296
persistent identifier	https://treatment.plazi.org/id/CB073541-3BA9-4A8D-AE2A-0E2A0F99F44B
taxon LSID	lsid:zoobank.org:act:CB073541-3BA9-4A8D-AE2A-0E2A0F99F44B
treatment provided by	Plazi
scientific name	Hippolyte cedrici
status	sp. nov.

Treatment

Hippolyte cedrici View in CoL sp. nov.

( Figs. 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

http://zoobank.org/ CB073541-3BA9-4A8D-AE2A-0E2A0F99F44B

Hippolyte View in CoL sp.—d’Udekem d’Acoz, 2007: 198, Fig. 11 View FIGURE 11 .

Hippolyte View in CoL sp. nov.— Wirtz, 2018: 43.

Material examined. São Tomé Island : holotype ovigerous female (pocl 1.5 mm), stn. 22, dive site “Canyon”, about 100m west of Santana islet (0.245 6.748), on Tanacetipathes spinescens (Gray, 1857) , 34m, leg. P. Wirtz, 6.ii.2017 (RMNH.CRUS.D.57330); 17 paratype specimens (pocl 1.1–1.5 mm), same data ( OUMNH. ZC.2018-01- 076) ; 11 paratype specimens including 1 ovigerous female (pocl 0.8–1.4 mm), stn. 29, same location, on T. spinescens , 37m, leg. P. Wirtz, 9.ii.2017 ( RMNH. CRUS.D.57331) ; 9 paratype specimens including 2 ovigerous females (pocl 1.0– 1.4 mm), stn. 30, same location, on Antipathella wollastoni (Gray, 1857) , 37m, leg. P. Wirtz, 9.ii.2017 ( RMNH. CRUS.D.57332) .

Description. Carapace stout. In females ( Fig. 1 View FIGURE 1 A–C), rostrum moderately narrow, as long as or slightly longer than carapace, exceeding antennular peduncle, with postrostral tooth, 3 dorsal teeth on rostrum proper of which distalmost close to tip of rostrum; 2 ventral teeth, distalmost just in front of level of distal dorsal tooth, proximal tooth between level of distal two dorsal teeth. Rostrum in males ( Fig. 1B View FIGURE 1 ) more slender, slightly shorter than in females, with 3 dorsal teeth and usually one subdistal ventral tooth. Hepatic tooth robust, reaching anterior margin of carapace. Antennal tooth small, just below slightly protruding infraorbital angle. Pterygostomial angle slightly protruding.

Third pleonite ( Fig. 1 View FIGURE 1 ) dorsal outline in lateral view distinctly curved. Fifth pleonite without tooth above tergite-pleuron junction. Ratio between dorsal length and height of sixth pleonite: 3.4. Telson apex ( Fig. 6B View FIGURE 6 ) with 6 strong terminal cuspidate setae (external ones distinctly shorter than intermediate and median ones); one short cuspidate seta present on each side between intermediate and median ones; usually 4 (sometimes 2 or 3) short setae present between long median ones. Proximal pair of dorsolateral cuspidate setae between proximal third and middle of telson ( Fig. 6A View FIGURE 6 ); distal pair of dorsolateral cuspidate setae usually between first pair and telson apex.

Unpigmented part of eyestalk ( Fig. 1A, C View FIGURE 1 ) (measured dorsally from where it begins to broaden to base of cornea) longer than broad and longer than cornea. Cornea overreaching stylocerite.

Antennular peduncle ( Fig. 1D View FIGURE 1 ) reaching 0.7 of scaphocerite in mature females. First joint of antennular peduncle without distal outer tooth. Stylocerite moderately long, reaching 0.7 of first joint of antennular peduncle in mature females. Outer antennular flagellum about as long as inner antennular flagellum. Outer antennular flagellum with 6–9 joints in females: 5–6 thick proximal and 1–3 thin distal joints; first thick joint 1.7 times as long as wide, other thick joints slightly longer than broad or about as long as broad. Inner antennular flagellum with 9– 10 joints. Outer antennular flagellum in males usually with more thick joints than in females.

Scaphocerite of antenna ( Fig. 1E View FIGURE 1 ) 3.6 times as long as wide. Distolateral tooth of scaphocerite far from reaching tip of blade. Distolateral tooth and blade separated by distinct notch. Basicerite with distinct ventrolateral tooth. Carpocerite short, falling short of distal margin of basal segment of antennular peduncle.

Mandible ( Fig. 2A View FIGURE 2 ) with incisor and molar process, without palp. Incisor process with 5 teeth. Molar process with several bristles of short and robust setae.

Maxillula ( Fig. 2B View FIGURE 2 ) with upper lacinia broadly rectangular with two rows of stout spines medially and few long plumose setae anteriorly and posteriorly. Lower lacinia slender, curled inwards, with few distal serrulate setae. Palp distally with one long, scarcely plumose seta.

Maxilla ( Fig. 2C View FIGURE 2 ) with basal endite bilobed; distal lobe medially with slender serrulate setae and few long plumose setae anteriorly; proximal lobe slightly larger than distal lobe, medially with serrulate setae. Coxal endite short, medially with row of long plumose setae. Scaphognathite well developed. Palp short, distally with one plumose seta.

First maxilliped ( Fig. 2D View FIGURE 2 ) with coxal and basal endites partly fused, large and broad; basal endite medially with slender serrulate setae; coxal endite medially with long plumose setae. Exopod well developed, distally with 4 plumose setae; caridean lobe narrow. Epipod small, faintly bilobed. Palp long and slender with plumose setae medially and distally.

Second maxilliped ( Fig. 3A View FIGURE 3 ) with dactylar segment of endopod about twice as broad as long, densely fringed medially with long serrulate setae. Propodal segment anteriorly with few long simple and plumose setae. Carpal segment short, unarmed, triangular. Meral segment short, unarmed, triangular. Ischial segment slightly longer than broad, ventromedially with row of simple sort setae and dorsomedial row of longer plumose setae. Basal segment medially with long plumose setae; exopod about twice as long as bent endopod, distally with few plumose setae. Coxal segment fused with basal segment, laterally with bilobed epipod.

Third maxilliped ( Fig. 3B View FIGURE 3 ) reaching about mid-length of scaphocerite when extended forward. Distal segment medially with few rather short serrulate setae, with about 10 large conical teeth on apex and distal third of medial border. Penultimate segment 0.5 times length of distal segment. Antepenultimate segment about as long as distal two segments together, with small distolateral spine, with simple setae in distal 2/3 rd of medial margin and plumose setae in proximal third of mesial margin; exopod reaching mid-length of antepenultimate segment, distally with few plumose setae. Coxal segment medially expanded with row of plumose setae along medial margin, without epipod nor arthrobranch.

First pereiopod ( Fig. 3C View FIGURE 3 ) short, compact. Mesial side of chela not deeply concave. Fingers about as long as palm, spatulate, cutting edges entire. Carpus as long as chela, tapering proximally, unarmed. Merus as long as carpus, about twice as long as width, unarmed. Ischium short, basal segment slightly longer, ischial and basal segment combined slightly shorter than merus, medially both with several long plumose setae. Coxal segment almost as long as wide, medially with long plumose seta.

Second pereiopod ( Fig. 3D View FIGURE 3 ) long and slender, reaching mid-length of scaphocerite when extended. Chela with fingers slightly longer than palm, with entire cutting edges. First joint of carpus about as long as second and third joints combined; first joint 3.0–3.5 times as long as wide, second joint 1.6–1.7, third joint 1.7–1.8 respectively. Merus slender, slightly shorter than carpus. Ischium about half length of merus, unarmed. Basal segment short, half length of ischium, unarmed. Coxal segment medially with few long simple setae.

Ambulatory pereiopods rather long and slender. Third pereiopod ( Fig. 3E View FIGURE 3 ) almost reaching or slightly overreaching distal margin of scaphocerite when extended forward. Merus in mature females about 7.3 times as long as wide, carpus of third pereiopod 3.6 times as long as wide, propodus 8.7 times as long as wide. Merus with 1 subdistal outer spine. Carpus with 1 proximal outer spine. Propodus with 3 single ventral spinules in proximal 2/ 3 and 3 pairs of ventral spinules in distal third; lateral one in each pair longest. Dactylus ( Fig. 5a View FIGURE 5 ) about third of propodus length, corpus slightly curved, tapering distally, flexor margin with row of 6 spinules increasing in length distally; unguis slender, twice as long as distalmost spine on corpus (secondary unguis).

Fourth pereiopod ( Fig. 4A View FIGURE 4 ) similar to third. Merus without subdistal outer spine. Carpus with 1 proximal outer spine. Propodus with 3 single ventral spinules in proximal 2/3 and 3 pairs of ventral spinules in distal third; lateral one in each pair longest. Corpus of dactylus ( Fig. 5B View FIGURE 5 ) with 5 spinules along flexor margin.

Fifth pereiopod ( Fig. 4B View FIGURE 4 ) similar to fourth. Propodus with 2 single ventral spinules in proximal 2/3 and 3 pairs of ventral spinules in distal third; lateral one in each pair longest. Corpus of dactylus ( Fig. 5C View FIGURE 5 ) with 5 spinules along flexor margin.

Eggs small (diameter variable, depending on their developmental stage).

First pleopod of male ( Fig. 6D View FIGURE 6 ) with endopod less than third length of exopod; medial margin of endopod with row of simple setae; lateral margin of endopod with row of long plumose setae.

Second pleopod of male ( Fig. 6E View FIGURE 6 ) with endopod slightly shorter than exopod; appendix masculina and appendix interna subequal; appendix masculina stout, distally with 6 finely serrulate long setae.

Ambulatory pereiopods in males ( Fig. 6C View FIGURE 6 ) distoventrally broadened, with series of paired, ventral serrulate spinules.

Colour. Not known.

Measurements. Maximum pocl in ovigerous females 1.6 mm; maximum pocl in males 1.4 mm.

Etymology. Named after our friend and colleague, Dr. Cédric d’Udekem d’Acoz, in recognition for his important contributions to the taxonomy of Hippolyte .

Host. All known specimens were collected from the antipatharians Tanacetipathes spinescens and Antipathella wollastoni , and the alcyonarian Muriceopsis tuberculata [as M. truncata in d’Udekem d’Acoz 2007 ]. It is not known at this stage whether these records represent obligate or facultative associations. As stated by d’Udekem d’Acoz (2007), given the lack of specific modifications of the ambulatory pereiopods, it could also simply be a ubiquitous species, occasionally encountered on cnidarians.

Distribution. Presently only known from São Tomé and Príncipe in the Gulf of Guinea, tropical East Atlantic.

Systematic Remarks. The new species can be easily differentiated from the majority of Atlantic Hippolyte species by the following characters: absence of tooth above tergite-pleuron junction on fifth pleonite (vs. present in H. coerulescens ); absence of teeth on outer distal corner of first peduncular article of antennula (vs. 2–3 in H. obliquimanus ); absence of post-rostral teeth (vs. present in H. garciarasoi , H. leptocerus , H. sapphica ); distal article of third maxilliped non-setose (vs. setose in H. catagrapha , H. leptometrae ); absence of double row of spinules on merus of third and fourth pereiopod (vs. present in H. inermis ); presence of single secondary unguis on dactylus of third and fourth pereiopod present (vs. absent in H. longiallex , H. nicholsoni , or with two ungui in H. pleuracanthus , H. zostericola ); rostrum with dorsal tooth present (vs. absent in H. lagarderei , H. palliola , H. prideauxiana ) and the distinctly curved dorsal profile of the third pleonite (vs. hardly recurved in H. niezabitowskii ). The new species thus clearly seems allied to H. varians and H. holthuisi , as already stated by d’Udekem d’Acoz (2007). The morphological differences between H. holthuisi and H. varians are both slight and geographically variable ( d’Udekem d’Acoz 1996, 2007, García-Raso et al. 1998), but whilst both taxa have previously been considered to be the same species ( d’Udekem d’Acoz 1996), they are clearly genetically distinct ( Terossi et al. 2017). Hippolyte cedrici sp. nov. can easily be distinguished from both H. holthuisi and H. varians on the basis of rostral dentition, with 2 (3 in a single specimen) well-developed proximal dorsal teeth in addition to the subdistal dorsal tooth in H. cedrici sp. nov., vs. 1 (very rarely 2) less developed teeth in the other two species, as well as the lower number of spinules on the dactyli of the ambulatory pereiopods (5–6 vs. 8–11 in the other species). Compared to Atlantic populations of H. varians ( García-Raso et al. 1998) and the Mediterranean H. holthuisi ( d’Udekem d’Acoz 1996, García-Raso et al. 1998), the new species also has a lower number of spines on the merus of the third pereiopod, 1 vs. 3–4 in H. holthuisi and 4–7 in H. varians . Finally, the new species has the telson distal margin with an extra set of small cuspidate setae between the median and intermediate long ones which is lacking in H. varians and H. holthuisi .