A NEW SPECIES OF CAPRELLA (AMPHIPODA, CAPRELLIDAE) FROM DEEP SEA WATERS

A NEW SPECIES OF CAPRELLA (AMPHIPODA, CAPRELLIDAE) FROM DEEP SEA WATERS BY J. M. GUERRA-GARCÍA 1 / and J. C. GARCÍA-GÓMEZ Laboratorio de Biología Marina, Departamento de Fisiología y Biología Animal, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, E-41012 Sevilla, Spain ABSTRACT A new species of caprellid, Caprella sabineae n. sp. is described and illustrated based on specimens from Sagami, Japan, collected at 600 meters deep, during the Dr. Sixten Bock Japan Expedition 1914. The new species is close to Caprella chelimana Mayer, 1903 but can easily be distinguished, mainly by the absence of a dorsal projection on the head and the presence of only one grasping spine on the palm of the male gnathopod 2. RESUMEN Se describe e ilustra una especie nueva de caprélido, Caprella sabineae, a partir de ejemplares recolectados a 600 metros de profundidad en Sagami, Japón, durante la Expedición Dr. Sixten Bock 1914. La especie nueva es parecida a Caprella chelimana Mayer, 1903 pero puede diferenciarse fácilmente de ella por la ausencia de la proyección dorsal de la cabeza y la presencia de sólo una espina en la palma del gnatópodo 2 en los machos. INTRODUCTION During a stay at the Swedish Museum of Natural History, the rst author (JMGG) examined the caprellids collected during the Dr. Sixten Bock Japan Expedition in 1914. Most of the amphipod material of this collection belongs to the suborder Gammaridea, but two species of the suborder Caprellidea were found: Caprella scaura Templeton, 1836, and an undescribed species of Caprella, collected from 600 meters deep. Taking into account that a hundred of specimens of this species were studied, we present here a complete taxonomic description of the species including notes of intraspeci c variation and morphological changes during development. All the material of the new species is deposited in the Swedish Museum of Natural History (SMNH). 1 / e-mail: jmguerra@us.es Koninklijke Brill NV, Leiden, 2003 Crustaceana 76 (5): 581-590 Also available online: www.brill.nl

582 J. M. GUERRA-GARCÍA & J. C. GARCÍA-GÓMEZ DESCRIPTION Caprella sabineae new species ( gs. 1-5) Type material. Holotype, adult male (SMNH T-5763), 16.1 mm body length, Misaki, Sagami, Japan, 600 m depth, 26 June 1914 (Sixten Bock Japan Expedition 1914). Allotype, adult female (SMNH T-5764), 9.4 mm body length, collected together with the holotype. Other paratypes (SMNH T-5765): 3 adult males, 3 adult females, 15 subadult males, 25 premature females, 52 juveniles, collected together with the holotype. Diagnosis (based on male specimens). Two dorsal tubercles on pereonite 2, an acute dorsal projection on pereonite 4, and two small acute projections laterodorsally near the coxae on pereonites 5-7. Basis of gnathopod 2 elongate, as long as pereonite 2; merus with a rounded projection; propodus palm provided with two well-developed projections, the rst one carrying a grasping spine. Abdominal appendages 1-articulate. Etymology. The species is dedicated to Dr. Sabine Stöhr for her hospitality and kindness during the stay of JMGG at the Swedish Museum of Natural History. Description. Holotype male (SMNH T-5763): body length 16.1 mm. Head without rostrum or dorsal projection. Pereonites 2 and 3 subequal in length. Pereonite 2 with two dorsal tubercles. Pereonite 4 with an acute dorsal projection distally. Pereonites 5-7 with two small acute projections laterodorsally near the coxae. Gills elongate, about 4 times as long as wide. Upper lip symmetrically bilobed, with short setae distally. Left mandible with incisor 5-toothed, lacinia mobilis 5-toothed, and a row of 3 plumose setae. Right mandible with incisor 5-toothed, lacinia mobilis 6-7 toothed, and 2 plumose setae; molar ake present. Lower lip with inner lobes well-demarcated, rectangular; inner and outer lobes pubescent. Maxilla 1 outer lobe with 7 forked spines distally; distal article of the palp with 6 strong spines and 5 teeth distally, and 10 setae medially. Maxilla 2 outer lobe rectangular, with 13 setae distally; inner lobe oval, with 17 simple setae and a plumose seta. Maxilliped inner plate carrying 8 plumose setae and 3 teeth; outer plate, slightly shorter than inner plate, with 4 teeth; palp setose, dactylus provided with tiny setulae. Antenna 1 about 3/4 of body length; agellum 28-articulate. Antenna 2 about 1/3 as long as antenna 1, carrying short swimming setae. Gnathopod 1 basis as long as ischium to carpus combined, provided with an acute distal projection; ischium short and rectangular; palm setose, with 2 grasping spines proximally and smooth margin; grasping margin of dactylus minutely serrate. Gnathopod 2 inserted on the posterior half of pereonite 2; basis as long as pereonite 2, with an acute projection distally; ischium short, rectangular, with an acute projection distally; merus rounded, with a projection medially; carpus short,

CAPRELLA SABINEAE NOV. 583 Fig. 1. Caprella sabineae n. sp. Lateral view. A, male; B, female. Scale bar: 1 mm. subequal; propodus 1.3 times as long as basis, elongate, with two well-developed, striking projections, the proximal one with a grasping spine; a row of setae between the projections and the dactylus; dactylus short and curved, widened proximally, margin smooth.

584 J. M. GUERRA-GARCÍA & J. C. GARCÍA-GÓMEZ Fig. 2. Caprella sabineae n. sp., male. A, upper lip; B, lower lip; C, maxilliped; D, maxilla 1; E, maxilla 2; F, left mandible; G, right mandible. Scale bars: 0.2 mm.

CAPRELLA SABINEAE NOV. 585 Fig. 3. Caprella sabineae n. sp. A-D, male: A, antenna 1; B, antenna 2; C, gnathopod 1; D, gnathopod 2. E, female gnathopod 2. Scale bars: A, B, D, E, 1 mm; C, 0.4 mm.

586 J. M. GUERRA-GARCÍA & J. C. GARCÍA-GÓMEZ Fig. 4. Caprella sabineae n. sp. A-E, male: A, pereopod 5; B, pereopod 7; C, abdomen (ventral view). D, female abdomen (ventral view). Scale bars: A, B, 1 mm; C, D, 0.2 mm. Pereopods 3 and 4 absent. Pereopods 5-7 missing in the holotype (drawings are from a male paratype), similar in size and shape, with a pair of proximal grasping spines. Penes large, 2 times as long as wide, situated medially. Abdomen with a pair of 1-articulate appendages, a pair of lateral lobes, and a single dorsal lobe with 2 plumose setae distally. Allotype female (SMNH T-5764): body length 9.4 mm. The pair of dorsal tubercles on pereonite 2 is lacking. Basis of gnathopod 2 shorter than pereonite 2; palm without the two well-developed projections present in the male, provided with 3 grasping spines. Abdomen without appendages. Oostegites on pereonite 3 slightly setose, on pereonite 4 non-setose.

CAPRELLA SABINEAE NOV. 587 Fig. 5. Caprella sabineae n. sp. Male gnathopod 2 during development. Scale bar: 1 mm. Intraspeci c variation and ontogenetic development. Body length: males 14:4 1:6 mm (mean standard deviation), range 12.8-17.9 mm. Females 8:6 1:0 mm (6.8-10.4 mm). The body projections are constant in all adult specimens. The tubercles and the projections become more conspicuous throughout development. The young males lack the pair of tubercles dorsally on pereonite 2, although the dorsal projection on pereonite 4 and the small lateral projections on pereonites 5-7 appear soon, being already present in the juveniles.

588 J. M. GUERRA-GARCÍA & J. C. GARCÍA-GÓMEZ Gnathopod 2 is of constant shape in adults but it considerably changes in males during development ( g. 5). Initially, the male propodus is wider, provided with a large grasping spine but without projections. A small projection appears distally in the juveniles, and this projection progressively increases in size and moves to mid-length of the palp. The grasping spine becomes reduced in size and another projection (carrying the grasping spine) appears and increases in size during development. The proximal end of the propodus becomes elongate in the last stages. The setae, initially distributed around the whole palm, are increasingly concentrated on the distal end. The number of articles in the agellum of antenna 1 varies between 25 and 29 in males and between 23 and 27 in females. The antenna 2 agellum is always 2-articulate. Regarding the mouthparts, the mandibles invariably have a 5-toothed incisor. The lacinia mobilis is always 5-toothed in the left mandible but varies in the right mandible depending on the specimen, ranging from 5 to 7-toothed, or even to serrate and not clearly toothed. The maxilliped inner plate always has 3 teeth and the outer plate 4 teeth in adult specimens. The juveniles have only 3 and 2 teeth in the inner and outer plate, respectively. REMARKS Caprella is the largest genus of the suborder Caprellidea, widely distributed from temperate to boreal regions and occurring primarily on seaweeds, seagrasses, and hydroids (Takeuchi, 1993). Japanese waters have been shown to host one of the highest species richnesses of the Caprellidea world-wide (McCain & Steinberg, 1970; Takeuchi, 1999; Guerra-García et al., 2000). More than 130 species of the genus Caprella have been reported so far throughout the world (Takeuchi, 1993) and 70 of these are present in Japanese waters (Takeuchi, 1999). The new species, Caprella sabineae n. sp. is close to C. chelimana Mayer, 1903, mainly by the feature of male gnathopod 2. But the two species can be easily distinguished, mainly on the basis of the following characteristics: (1) C. chelimana has a distinct acute projection on the head dorsally (Mayer, 1903), while the head of C. sabineae is smooth; (2) males of C. sabineae have a pair of dorsal tubercles on pereonite 2, which are lacking in C. chelimana; (3) C. chelimana possesses lateral projections on pereonites 3 and 4, which are absent in C. sabineae; instead of this, C. sabineae only has an acute dorsal projection distally on pereonite 4; (4) the merus of gnathopod 2 has a round projection in C. sabineae, which is lacking in C. chelimana; (5) the propodus palm of the male gnathopod 2 has two grasping spines in C. chelimana and only one in C. sabineae.

CAPRELLA SABINEAE NOV. 589 Caprella sabineae n. sp. was found in samples collected at 600 meters deep. Generally, the species of the genus Caprella are associated with shallow waters. So far, only eighteen species of Caprella had been reported from waters below 400 meters (McCain, 1966; Guerra-García, in rev.): Caprella ciliata Sars, 1883, C. horrida Sars, 1877, C. microtuberculata Sars, 1879, C. rinki Stephensen, 1916, and C. septentrionalis Krøyer, 1879 are distributed in the Arctic and North Atlantic; C. extensimana Laubitz, 1995 was described recently from deep sea waters of the southern Indian Ocean; C. ungulina Mayer, 1903 has been found in the Paci c and South Atlantic; C. equilibra is a cosmopolitan species and the remaining ten species (C. bathyalis Vassilenko, 1972, C. bathytatos Martin & Pettit, 1998, C. centrota Vassilenko, 1972, C. constantina Mayer, 1903, C. mbrillata Vassilenko, 1993, C. indeterminata Vassilenko, 1993, C. irregularis Mayer, 1890, C. longicirrata Vassilenko, 1974, C. oxyarthra Vassilenko, 1974, and C. paci ca Vassilenko, 1972) are distributed in the north-west Paci c. The majority of these deep sea species have also been reported from shallow waters and are not restricted to the deeper areas (Stephensen, 1944; Laubitz, 1972; Takeuchi et al., 1989; Vassilenko, 1993; Larsen, 1998). Probably, future studies will report Caprella sabineae also from shallower waters. ACKNOWLEDGEMENTS Special thanks to everybody at the Swedish Museum of Natural History for the hospitality and facilities provided. The stay at the Swedish Museum of Natural History was supported by the European Community (Access to Research Infrastructure action of the Improving Human Potential Programme), through HIGH LAT resources (project number HPRI-CT-2001-00125). REFERENCES GUERRA-GARCÍA, J. M., J. E. SÁNCHEZ-MOYANO & J. C. GARCÍA-GÓMEZ, 2000. Redescription of Caprella hirsuta Mayer, 1890 (Crustacea, Amphipoda, Caprellidea) from the Strait of Gibraltar. Miscellània Zoològica, 23: 69-78. LARSEN, K., 1998. Caprellidea (Crustacea, Amphipoda) from Faroe Islands waters, with a key to the North-Atlantic species. Fródskaparrit, 46: 81-90. LAUBIT Z, D. R., 1972. The Caprellidea (Crustacea: Amphipoda) of Atlantic and Arctic Canada. Publications in Biological Oceanography, 4: 1-82. MAYER, P., 1903. Die Caprelliden der Siboga-Expedition.Siboga Expeditie Monographs, 34: 1-160. MCCAIN, J. C., 1966. Abyssicaprella galatheae, a new genus and species of abyssal caprellid (Amphipoda, Caprellidae). Galathea Report, 8: 91-95. MCCAIN, J. C. & J. E. STEINBERG, 1970. Amphipoda I. Caprellidea I. Fam. Caprellidae. In: H. E. GRUNER & L. B. HOLTHUIS (eds.), Crustaceorum Catalogus, 2: 1-78. STEPHENSEN, K., 1944. Malacostraca 8, Amphipoda 4. The Danish Ingolf Expedition, 3: 1-51.

590 J. M. GUERRA-GARCÍA & J. C. GARCÍA-GÓMEZ TAKEUCHI, I., 1993. Caprella arimotoi, a new species (Crustacea: Amphipoda: Caprellidea) from the Seto Inland Sea, Japan. Proceedingsof the Biological Society of Washington, 106: 115-121., 1999. Checklist and bibliography of the Caprellidea (Crustacea: Amphipoda) from Japanese waters. Otsuchi Marine Science, 24: 5-17. TAKEUCHI, I., M. TAKEDA & K. TAKESHITA, 1989. Redescription of the bathyal caprellid, Caprella ungulina Mayer, 1903 (Crustacea,Amphipoda) from north Paci c. Bulletin of Natural Sciences Museum of Tokyo, (A) 15: 19-28. VASSILENKO, S. V., 1993. Caprogammarus and caprellids (Amphipoda, Caprellidea) of the continental slope of the Kurile Islands. Issledovaniya Fauny Morei, 46: 130-155. [In Russian.] First received 5 December 2002. Final version accepted 6 March 2003.