Org. Divers. Evol. 3, Electr. Suppl. 16: 1 - 10 (2003) © Gesellschaft für Biologische Systematik http://senckenberg.de/odes/03-16.htm

The of the amphipod Stilipes (Crustacea: : ), with description of one new

Jørgen Berge

Department of Biology, UNIS, Box 156, 9171 Longyearbyen, Norway Received 18 May 2003 - Accepted 11 July 2003 e-mail: [email protected]

Abstract

A new species of marine amphipod, Stilipes macquariensis sp. n., is described from west of Macquarie Island. Two of the previously known species in the genus, S. distinctus and S. lacteus, are partly redescribed, and a key to Stilipes species is presented. The name of the species originally published as Stilipes distincta Holmes, 1908 is changed to S. distinctus as mandated by the Code of zoological nomenclature (ICZN 1999: Article 34.2.), to match the gender of the genus name. Detailed studies of various appendages have revealed that, contrary to what was believed until now, members of Stilipes do possess both a small accessory flagellum on the first antenna and a row of raker setae on the mandible (Fig. 1). Relations of the genus to the three families Astyridae, Stilipedidae and Iphimediidae (all sensu Coleman & Barnard 1991) are discussed. Key words: Amphipoda, Stilipes macquariensis sp. n., taxonomy

Introduction

The genus Stilipes was first erected by Holmes Holman & Watling 1983, Barnard & Karaman 1991, (1908) to encompass the new species Stilipes Coleman & Barnard 1991). Pending a revision of the distinctus from San Nicolas Island off the coast of group, the classification of Coleman & Barnard southern California. Holmes, at the same time, also (1991: 263) is here retained, but the relationships erected the family Stilipedidae as a monotypic between Stilipes and other genera within the three taxon. Probably unaware of this genus, K. H. families Astyridae, Stilipedidae and Iphimediidae Barnard (1931) erected the genus Cacao for his new are discussed. species C. lacteus, collected in the eastern mid- Atlantic, treating it, along with the genus Alexandrella Chevreux, 1912, as belonging to the Material and methods family Tironidae. In 1954, Hurley described a second species within the same genus, Cacao This study is based upon material from the South sanguineus Hurley, 1954, but added his strong Australian Museum (Adelaide), the Natural History scepticism for retaining the genus within the Museum (London), the Zoological Institute in St. Tironidae. It was not until Shoemaker (1964) Petersburg, and the U. S. National Museum in realised the close relationship between these three Washington, D.C. All dissected appendages were species, that they were all unified within the genus prepared in glycerol, and drawn using a Leica Stilipes (family Stilipedidae). compound microscope equipped with a drawing Later authors have all treated the three species as tube. Mature and immature females were congeneric, but the status of the family Stilipedidae distinguished from males by the presence of has remained somewhat in a state of flux (e.g. oostegites. The classification of setae and setae groups follows that of Berge (2001).

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Abbreviations: A1 / A2 = antenna 1 / 2; EP3 = Remarks: The genus Stilipes is morphologically epimeral plate 3; IP = inner plate; L = labium; LBR strongly unified, consisting of four very similar = labrum; LMND = left mandible; MX1 / MX2 = species. It is primarily characterised by the large and maxilla 1 / 2; MXP = maxilliped; OP = outer plate; bulging head, in combination with the extraordi- P1-7 = pereopods 1-7; PLP = palp; RMND = right narily large palp of the first maxilla. It was mandible; ST = setal teeth on first maxilla; T = previously thought to lack both an accessory telson; U1-3 = uropods 1-3. flagellum on the first antenna and a row of raker setae on the mandibles. However, both these morphological traits are herein reported to be present Taxonomy in all three examined species (no material was available for S. sanguineus). Key to the species of Stilipes Holmes K. H. Barnard (1932) recognised the strong mor- phological affinities between Cacao lacteus and the 1. Pereopod 7 distinctly longer than pereopods genus Alexandrella, but concluded that they ought to 5 or 6 ...... 2 be kept separate due to “the presence of eyes - Pereopods 5-7 subequal in length [Stilipes], the shape of the maxilliped, and other less ...... S. lacteus [eastern mid-Atlantic] important differences” (op. cit.: 153). There are also 2. Epimeral plate 3 posteroventrally produced and other appendages that, in my opinion, link these two pointed ...... 3 groups together, first of all the mandible and the - Epimeral plate 3 posteroventrally not produced morphology of the urosome. In both groups, the and rounded incisor is transverse, and conspicuously broad and ...... S. macquariensis [Macquarie Island] smooth (although some Alexandrella spp. possess a toothed incisor). The first urosomite is anterodor- 3. Uropod 2 reaching beyond uropod 3 sally excavated with a conspicuous posterior medial ...... S. sanguineus [New Zealand] keel with lateral ridges. Furthermore, although the - Uropod 2 not reaching end of uropod 3 inner plate of the first maxilla is considerably ...... S. distinctus [North Pacific] smaller in Stilipes than in Alexandrella, both taxa possess two parallel rows of setae along the distal margin of the inner plate. There are, however, also Family Stilipedidae sensu Coleman & Barnard affinities between Stilipes and some species of the (1991) family Astyridae (sensu Coleman & Barnard 1991). This is first of all apparent with gardineri, Genus Stilipes Holmes, 1908 but to a lesser degree also with the other apparently pelagic species of Astyra (A. bogorovi, A. longidac- Stilipes Holmes 1908: 536 – Barnard & Karaman tyla, A. longipes, and A. zenckevitchi). Astyra (1991: 707) gardineri possesses, as do the species of Stilipes, a Cacao K. H. Barnard, 1931: 427 (type species: distally conspicuously broadened coxa 1, in addition C. lacteus K. H. Barnard, 1931) – Hurley (1954: to the large and bulging head and elongate antennae 804) and pereopods 5-7. Furthermore, the morphology of Type species: Stilipes distinctus Holmes, 1908. the fourth coxa in Stilipes is very similar to that in Astyra. Astyra species, on the other hand, do not Species included: Stilipes distinctus Holmes, 1908; possess the large and broad mandibular incisors and S. lacteus (K. H. Barnard, 1931); S. macquariensis palp of the first maxilla, although they do possess sp. n.; S. sanguineus (Hurley, 1954). two distal rows of setae on the inner plate of the first Morphological characteristics: Head large with maxilla. rostrum rudimentary, eyes present. Antennae long, The absence of an accessory flagellum on the first accessory flagellum rudimentary. Coxa 1 large, antennae and of raker setae on the mandibles have distally widened. Pereopods 5-7 elongate, pereopod both been considered as autapomorphic character 7 dactylus broad. Labrum short and symmetrically states separating Stilipes from the other stilipedid incised. Maxilla 1 palp very large, two-articulated, taxa. However, as the descriptions presented below inner plate small, with two rows of setae. show, both these features are present (although Mandibular incisors broad and smooth, left lacinia reduced) in at least three of the four species in the mobilis large and toothed, right absent. Uropod 3 genus. However, although this definitely reduces the rami long and lanceolate, telson weakly cleft. morphological differences between Stilipes and e.g.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 3

Alexandrella, no changes in classification are 9°38’S, 12°42’E, 200-230 m. 31 July 1927 proposed at this stage. Pending first of all revisions (collected at night). of the various astyrid and stilipedid genera, and later Distribution: Only known from the type locality hopefully a phylogenetic analysis of the group, the (see above). classification of genera is retained unchanged. Description: Body: Rostrum absent, eyes large, round and conspicuous. Epistome unproduced. Body Stilipes distinctus Holmes, 1908 dorsally smooth, but urosomite 1 dorsally with a strong carina posteriorly and a deep excavation Stilipes distincta Holmes, 1908: 536. – Gurjanova anteriorly. Coxae 1 anteriorly expanded, partly (1951: 12), Shoemaker (1964: 414), Barnard & covering the head. Perepods 5-7 and antennae Karaman (1991: 707) elongate. Nomenclature: The ending of the species name is Antennae: Antenna 1 shorter than antenna 2, here changed to S. distinctus, as mandated by the peduncle article 1 longer than articles 2 and 3 Code of zoological nomenclature (ICZN 1999: combined, flagellum elongate with more than 40 Article 34.2.), because the gender of the genus name segments. Accessory flagellum small, inconspicu- (derived from the Latin word ‘pes’ = foot) is male. ous, uniarticulate. Callynophore well developed. Antenna 2 peduncle article 4 shorter than five, Material examined: Okhotsk Sea; USNM Acc. No flagellum elongate with more than 40 segments. 177913: female (21 mm) and male (19 mm), Mouthparts: Labrum shorter than broad, distally 55˚56’N, 132˚04’W, 288 fathoms, 30 August 1905. convex and rounded. Labium distally pointed, inner Distribution: North Pacific, recorded from San lobes absent. Mandibles short, hinge line lateral. Nicolas Island (type locality), the southern end of Incisors smooth and broad. Lacinia mobilis absent Alaska and the Okhotsk Sea. Depth range 400-700 on right mandible, large and toothed on left meters. mandible. Accessory setae-row reduced, three Description: This species was thoroughly described simple setae. Molar absent. Palp 3-articulate, article by Shoemaker (1964), thus only a few comple- 2 longer than 3. Articles 2 and 3 with two rows of mentary notes are presented here: pectinate setae. Maxilla 1 palp two-articulate, Antenna 1 accessory flagellum rudimentary, distally very broad, distally and laterally with small uniarticulate. Labrum short, weakly and sym- simple setae. Outer plate broad, setal teeth in one metrically incised. Mandibles with raker setae row of 15 setae, setae not cuspidate. Inner plate present, setae short and simple. Maxilla 1 outer plate short, with two distal rows of pappopectinate setae. with setal teeth in one elongate row; inner plate with Maxilla 2 outer plate as broad as inner, both plate two rows of setae, one with long pappopectinate and distally with three distinct rows of setae. Maxilliped one with short pappose setae. inner plate distally without nodular setae, distal and No sexual dimorphism was observed. medial setae-rows parallel and well developed with 4 and 8 short pectinate setae. Outer plate heavily Remarks: The material examined in the collections setose, inner margin with two rows of short setae, of the U. S. National Museum of Natural History distally with one row of long pectinate setae. Palp 4- (see above) is the same on which Shoemaker (1964: articulate, article 1 laterally heavily setose, article 2 414) based his description of this species. longer than 3. Pereopods: Pereopods 1 and 2 similar to those of Stilipes lacteus (K. H. Barnard, 1931) S. macquariensis sp. n. (see figure 5). Pereopod 1 simple, basis with long simple setae on both anterior (Figs 1, 2) and posterior margins, ischium short with long Cacao lacteus K. H. Barnard, 1931: 428. – K. H. simple setae along posterior margin. Carpus broad, Barnard (1932: 153). longer than propodus, dactylus powerful and Stilipes lacteus (K. H. Barnard) – Barnard & smooth. Pereopod 2 simple, basis with long simple Karaman (1991: 707). setae on both anterior and posterior margins, ischium short with long simple setae on posterodistal Material examined: Paratypes (Zoological Institute margin. Carpus broad and twice as long as propodus, in St. Petersburg and Natural History Museum in dactylus powerful and pectinate. Coxa 1 large, London); eastern mid-Atlantic, Discovery stn. 273. produced anteriorly. Coxae 2 and 3 long and narrow, weakly shorter than coax 1. Coxa 4 posterior lobe

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 4 acute, posterodistal margin weakly concave, distally covering the head. Perepods 5-7 and antennae acute. Coxae 5-7 with posterior lobe, anterior lobe elongate. absent. Pereopods 3 and 4 similar, posterior margins Antennae: Antenna 1 shorter than antenna 2, of basis, ischium, merus, carpus and propodus peduncle article 1 longer than articles 2 and 3 heavily covered with short robust setae. Pereopod 5 combined, flagellum elongate with more than 40 and 6 bases expanded and rectangular, weakly segments. Accessory flagellum small, inconspicu- setose. Propodus longer than carpus, dactylus short ous, uniarticulate. Callynophore well developed. and powerful. Pereopod 7 as long as pereopods 5 Antenna 2 peduncle article 4 as long as 5, flagellum and 6, basis broad, distally rounded. Propodus elongate with more than 40 segments. weakly longer than carpus, dactylus broad. Gills on Mouthparts: Labrum as long as broad, distally pereopods 2-7, oostegites on pereopods 2-5. convex and rounded, asymmetrical with left lobe Epimeral plate 2 posterodistally acute, epimeral absent. Labium distally pointed, inner lobes absent. plate 3 posteriorly rounded and weakly produced. Mandibles short, hinge line lateral. Incisors smooth Uropod 1 peduncle as long as rami, outer and inner and broad. Lacinia mobilis absent on right mandible, margins with robust setae. Outer ramus weakly large and partly toothed on left mandible. Accessory shorter than inner, outer and inner margins with setae-row reduced, 4 short simple setae. Molar robust setae, inner ramus outer and inner margins absent. Palp 3-articulate, article 2 longer than 3. with robust setae. Uropod 2 not reaching end of Articles 2 and 3 with two rows of pectinate setae. uropods 1 and 3. Peduncle shorter than rami, with Maxilla 1 palp two-articulate, distally very broad, robust setae on inner and outer margins. Outer ramus distally and laterally with small simple setae. Outer conspicuously shorter than inner, outer margin with plate broad, setal teeth in two parallel rows; one row robust setae, inner ramus with robust setae on outer of 24 setae covering the entire dital margin and one and inner margins. Uropod 3 peduncle shorter than reduced lateral row of 2 setae, setae not cuspidate. rami, without setae. Rami subequal, long and Inner plate short, with two distal rows of lanceolate, with short robust setae on both outer and pappopectinate setae. Maxilla 2 outer plate (similar inner margins. Outer ramus uni-articulate. Telson to that of S. lacteus, see figure 2) as broad as inner, longer than broad, distally excavate and rounded. both plate distally with three distinct rows of setae. Remarks: Barnard (1932: 154) describes the labrum Maxilliped inner plate distally with 5 small nodular as “asymmetrical bilobed”, wheras examination of setae, distal and medial setae-rows parallel and well the paratypes (see Fig. 1) revealed that the labrum in developed. Outer plate heavily setose, inner margin fact is short and only very weakly asymmetrical. with two rows of long setae, distally with one row of Furthermore, Barnard (op. cit.) describes the colour long pectinate setae. Palp 4-articulate, article 2 as “thoracic segments and legs chocolate, abdominal longer than 3. segments white, eyes pink”. The preserved paratypes Pereopods: Pereopod 1 simple, basis with long examined were colourless. simple setae on both anterior and posterior margins, ischium short with long simple setae along posterior margin. Carpus broad, longer than propodus, Stilipes macquariensis sp. n. dactylus powerful and smooth. Pereopod 2 simple, basis with long simple setae on both anterior and (Figs 3-5) posterior margins, ischium short with long simple Type material: Holotype (South Australian setae on posterodistal margin. Carpus broad and Museum, Adelaide; reg. nr C6074) female 22 mm: twice as long as propodus, dactylus powerful and W Macquarie Isl., 54˚50’5’’-54˚41’9’’S, pectinate. Coxa 1 large, produced anteriorly. Coxae 158˚40’99’’-158˚43’E, 956-9 m, FRV Southern 2 and 3 long and narrow, weakly shorter than coax Surveyor stn. 5501/52, 22 January 1999, leg. K. L. 1. Coxa 4 posterior lobe acute, posterodistal margin Gowlett-Holmes. straight, distally rounded. Coxae 5-7 with posterior Distribution: Only known from the type locality. lobe, anterior lobe absent. Pereopods 3 and 4 similar, posterior margins of basis, ischium, merus, carpus Description: Body: Rostrum absent, eyes large, and propodus heavily covered with short robust round and conspicuous. Epistome unproduced. Body setae. Pereopod 5 and 6 bases expanded and dorsally smooth, but urosomite 1 dorsally with a rectangular, weakly setose. Propodus longer than strong carina posteriorly and a deep excavation carpus, dactylus short and powerful. Pereopod 7 anteriorly. Coxae 1 anteriorly expanded, partly longer than pereopods 5 and 6, basis broad, distally rounded. Propodus weakly longer than carpus,

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 5 dactylus broad. Gills on pereopods 2-7, oostegites on References pereopods 2-4. Epimeral plate 2 posterodistally acute, epimeral Barnard, J. L. & Karaman, G. S. (1991): The plate 3 posteriorly rounded and unproduced. Uropod families and genera of marine gammaridean 1 peduncle as long as rami, outer and inner margins Amphipoda (except marine gammaroids). Part 2. with robust setae. Outer ramus weakly shorter than Rec. Aust. Mus. Suppl. 13(2): 419-866. inner, outer and inner margins with robust setae, Barnard, K. H. (1931): Diagnoses of new genera and inner ramus outer and inner margins with robust species of amphipod Crustacea collected during setae. Uropod 2 not reaching end of uropods 1 and 3. the ‘Discovery’ Investigations, 1925-1927. Ann. Peduncle shorter than rami, with robust setae on Mag. Nat. Hist. 10: 425-430. inner and outer margins. Outer ramus shorter than Barnard, K. H. (1932): Amphipoda. Discovery Rep. inner, outer margin with robust setae, inner ramus 5: 1-326. with robust setae on outer and inner margins. Berge, J. (2001): Revision of Stegosoladidus Uropod 3 peduncle shorter than rami, without setae. Barnard & Karaman, 1987 (Crustacea: Rami subequal, long and lanceolate, with short Amphipoda: Stegocephalidae); redescription of robust setae on both outer and inner margins. Outer two species and description of three new species. ramus uni-articulate. Telson as long as broad, J. Nat. Hist. 35: 539-571. distally irregularly excavate and truncate. Chevreux, E. (1912): Deuxième expédition dans Remarks: The species is easily separated from the l’Antarctique, dirigée par le Dr. Charcot, 1908- three known congeners by the short and distally 1910. Diagnoses d’Amphipodes nouveaux. Bull. truncate telson, and the broad and rounded third Mus. Hist. Nat., Paris 18: 208-218. epimeral plate. S. distinctus and S. sanguineus both Coleman, C. O. & Barnard, J. L. (1991): Revision of possess a conspicuously pointed and acute Iphimediidae and similar families (Amphipoda: posterodistal corner on the third epimeral plate, ). Proc. Biol. Soc. Wash. 104: 253- whereas it is weakly produced and more rounded in 268. S. lacteus. Furthermore, the lacinia mobilis of S. Gurjanova, E. F. (1951): Amphipods of the USSR macquariensis sp. n. is only partly toothed, whereas seas and adjacent waters (Amphipoda – the entire distal margin of the lacinia mobilis is Gammaridea). Izdatelstvo Akademii Nauk SSSR, strongly toothed in all congeners. Moskva + Leningrad. Holman, H. & Watling, L. (1983): A revision of the Stilipedidae (Amphipoda). Crustaceana 44: 27-53. Stilipes sanguineus (Hurley, 1954) Holmes, S. J. (1908): The Amphipoda collected by the U. S. Bureau of Fisheries steamer "Albatross" Cacao sanguineus Hurley 1954: 804. off the west coast of North America, in 1903 and Stilipes sanguineus (Hurley) – Barnard & Karaman 1904, with descriptions of a new family and (1991: 707). several new genera and species. Proc. U. S. Natl Distribution: Only known from its type locality Mus. 35(1654): 489-543. East of New Zealand. Hurley, D. E. (1954): Studies on the New Zealand amphipodan fauna. No. 10. A new species of Remarks: Material of this species was not available Cacao. Trans. R. Soc. New Zealand 82: 803-811. for examination, hence no additional descriptions or ICZN = International Commission on Zoological notes can be made. Hurley (1954), however, Nomenclature (1999): International Code of provided excellent figures and descriptions of the Zoological Nomenclature. Fourth Edition. species. xxix+306 pp., Int. Trust on Zool. Nomencl., London. Acknowledgements Shoemaker, C. R. (1964): Seven new amphipods from the west coast of North America with notes I am grateful to Prof. Wim Vader for his help with on some unusual species. Proc. U. S. Natl Mus. earlier drafts of the manuscript, and to Ellen Beck 115: 391-429. for her help with the illustrations. The author was funded by the Norwegian Research Council, project number 145384/432.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 6

Fig. 1: Stilipes lacteus (K. H. Barnard, 1932), paratype. Scale bars = 0.1 mm.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 7

Fig. 2: Stilipes lacteus (K. H. Barnard, 1932), paratype. Scale bar = 0.1 mm.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 8

Fig. 3: Stilipes macquariensis sp. n., holotype female, 22 mm. Scale bars = 0.1 mm.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003) Berge: Taxonomy of Stilipes (Amphipoda) 9

Fig. 4: Stilipes macquariensis sp. n., holotype female, 22 mm. Scale bars = 0.1 mm.

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Fig. 5: Stilipes macquariensis sp. n., holotype female, 22 mm. Scale bars = 0.1 mm.

Org. Divers. Evol. 3, Electr. Suppl. 16 (2003)