PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 120(4):429–445. 2007. New species and records of valviferan isopods (Crustacea: Isopoda: Valvifera) from the Indian Ocean

Brian Kensley{, Marilyn Schotte*, and Gary C. B. Poore (BK, MS) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013-7012, U.S.A., e-mail: [email protected]; (GCBP) Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia, e-mail: [email protected]

Abstract.—Four new species of valviferans are described: Arcturinoides angulata, Astacilla mccaini and Astacilla spinicutis (family Arcturidae), and Neoarcturus obesopleon (family Holidoteidae). Amesopous richardsonae (Arcturidae) is redescribed and reported from widely separate localities throughout the Indian Ocean, tropical Australia and Japan.

The marine isopod fauna of the Indian tralia held in Museum Victoria. This Ocean is recorded in many scattered paper does not repeat diagnoses of higher papers. The region has been unevenly level taxa; revisionary works are referred sampled, some few areas being relatively to in the generic synonymies. Illustrations well explored, but most of the region, were drafted by BK and completed by both shallow and deep waters, is poorly MS; the higher taxonomy is the decision known or uncollected. Few papers pro- of GCBP. Species are diagnosed using vide an overview of the isopod fauna of a suite of characters that differentiate the entire region (Bruce 1997, Kensley them from others in their respective 2001). This paper on the Valvifera con- genera; mouthparts and most limbs are tinues a series by the late Brian Kensley figured but described in words in only and Marilyn Schotte documenting the some cases. marine isopod diversity of the Indian AkeytoArcturinoides is offered. Ocean (see Kensley & Schotte 2000, 2002; Indian Ocean species of Astacilla are Schotte & Kensley 2005). listed with information on distribution. Here, four new species of Valvifera in Abbreviations.—IIOE - International two families are described and the range Indian Ocean Expedition; NMV - Muse- of another considerably extended. About um Victoria, Melbourne; SAM - South 56 species of valviferans have been African Museum, Cape Town; USNM - recorded from the Indian Ocean (Kensley National Museum of Natural History, 2001). The material reported here comes Smithsonian Institution; ZMUC - Zoo- from the western Indian Ocean (Zanzibar logical Museum, University of Copenha- Island) and from the International Indian gen. Scale bars on illustrations refer only Ocean Expedition (mid-1960s), collected to habitus drawings. off the east African coast and Madagas- car. It is supplemented by collections Systematics from the Persian Gulf, Japan and Aus- Family Arcturidae Sars, 1897 Amesopous Stebbing, 1905 {1 Deceased 19 January 2004. *2 Corresponding author. Amesopous Stebbing, 1905:44. 430 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Type species.—Amesopous richardsonae ry, Australia, New Year Island, N. side, Stebbing, 1905 (by monotypy). patch reef, 10u549S, 133u29E, 6–14 m, Remarks.—The monotypic genus Ame- sand and hydroids, J. K. Lowry, G. C. sopous is unique among the Arcturidae in B. Poore et al., 13–14 Oct 1982 (stns NT the combination of straight body form 3, 17, 20, 22). NMV J16490, 1 specimen, and absence of pereopods 3 and 4. The Northern Territory, Australia, Oxley Is- genus was placed in its own family, land, W. end, reef, 11u09S, 132u499E, 5 m, Amesopodidae, by Stebbing (1905) but coral sand and rubble, J. K. Lowry, 20 included with Arcturidae by Poore (2001), Oct 1982 (stn NT 75). NMV J16489, 10 Poore et al. (2002) and King (2003a). specimens, Northern Territory, Australia, Fannie Bay, W of East Point, 11u249S, Amesopous richardsonae Stebbing, 1905 130u489E, 8 m, hydroids etc., J. K. Figs. 1, 2 Lowry, 26 Oct 1982 (stn NT 90). NMV J16486, 4 specimens, Queensland, Aus- Amesopous richardsonae Stebbing, 1905: tralia, Lizard Island, Granite Head, 44, pl. 11A.—Poore, 2001:222–223.— 100 m offshore, sloping granite surface Poore et al., 2002:258. with some coral and sponge, 14u409S, 145u279E, 7 m, on hydroid Lytocarpus Material examined by BK and MS.— philippinus, G. C. B. Poore, 11 Dec 1987 USNM 221501, 2 males, 4.5 mm, 1 (stn NQ 127). NMV J16487, 1 specimen, ovigerous female, 5.0 mm, 10u549S, Queensland, Australia, Fantome Island. 133u029E, New Year Island, Northern coral reef on N side, 18u409S, 146u319E, Territory, Australia, sand and coral, 5 m, black hydroid, G. C. B. Poore and 14 m, coll. G. C. B. Poore, 14 Oct 1982; H. M. Lew Ton 5 Dec 1982 (stn NQ 12). USNM 253343, 1 male, 4.8 mm, 3 NMV J48652, 1 specimen, Western Aus- ovigerous females, 6.2–6.3 mm, 2 juve- tralia, Northwest Shelf, between Dampier niles, off Somalia, 11u249N, 51u359E, and Port Hedland, 19u29.79S, 118u52.29E, 150 m, 17 Dec 1964 (IIOE stn 463); 39 m, WHOI epibenthic sled, CSIRO USNM 253345, 2 ovigerous females, 2 Division of Fisheries, 24 Oct 1983 (stn juveniles, Bay of Bengal off Andaman NWA 276). NMV J16498, 1 specimen, Islands, 11u529N, 92u499E, 66 m, 27 Mar Japan, Tomioka, 3 m, on Sargassum 1963 (IIOE stn 28A); USNM 253346, 2 patens, G. Edgar, 12 Apr 1988. ovigerous females, southern Mozambi- Abbreviated description.—Female: Body que, 19u099S, 36u559E, 88 m, 9 Oct 1964 about 9 times longer than greatest width, (IIOE stn 403-E); USNM 253347, one widest at pereonite 3 in ovigerous female. ovigerous female, off Somalia, 11u379N, Cephalon with anterior margin concave, 51u279E, 18 Dec 1964 (IIOE stn 465). line of fusion with pereonite 1 marked by Material examined by GCBP.—NMV shallow groove; eyes large, oval, well J16488, 30 specimens; J48650, 4 speci- pigmented, lateral. Pleotelson with 2 fused mens; J16491, 2 specimens; J16495, 19 segments marked by shallow grooves, plus specimens; J48651, 1 specimen; J16496, 2 tapering pleotelson. Antennule having specimens: Northern Territory, Australia, flagellum of 2 articles, basal article very McCluer Island, 11u29S, 132u589E, 8 m, short; with 2 distal aesthetascs. Antenna on coral Acropora, sand and yellow half length of body; 3 distal peduncle hydroid habitats, J. K. Lowry, G. C. B. articles elongate, cylindrical; flagellum of Poore et al., 16–17 Oct 1982 (stns NT 33, 3 articles, with terminal claw. Mandible 45, 52–54). NMV J16493, 18 specimens; molar broadly truncate, strong; lacinia J16497, 1 specimen; J16492, 3 specimens; mobilis bifid. Maxillipedal palp article 2 J16494, 50 specimens: Northern Territo- with 3 circumplumose setae on mesial VOLUME 120, NUMBER 4 431

Fig. 1. Amesopous richardsonae Stebbing. a, b, ovigerous female in dorsal and lateral views, scale 5 2.0 mm; c, antennule; d, antennal flagellum; e, mandible; f, g, maxillae 1, 2; h, maxilliped; i, penial plate; j, uropodal rami. margin; article 3 with 7 setae, article 4 with pus and propodus bearing row of strong 5 setae; terminal article with single circum- tridentate setae on mesial margin; dactylus plumose setae and 3 simple setae; endite short, as long as wide, bearing 3 distal bearing 2 coupling hooks, 3 stout fringed simple setae; basis almost as long as setae mesiodistally. Pereopod 1 with car- carpus, merus, and ischium together. 432 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 2. Amesopous richardsonae Stebbing. a–e, pereopods 1, 2, 5–7; f, g, male pleopods 1, 2.

Pereopod 2 ambulatory, with distinct lus biunguiculate. Uropodal apex with basis; ischium-merus weakly defined, bear- reduced endopod bearing 3 distal setae. ing row of triangular teeth on posterior Male: Body similar to female. Penes margin; carpus-propodus fused, with pos- fused as a single structure, basally broad, terior denticles; dactylus bearing 3 teeth on tapering distally. Pleopod 1 peduncle posterior surface. Pereopods 5–7 robust, subequal in length to endopod, with 3 ambulatory/prehensile, similar, but with coupling hooks; endopod bearing 8 elon- basis becoming shorter posteriorly; dacty- gate plumose setae on distal margin; VOLUME 120, NUMBER 4 433 exopod with proximal notch on lateral – Lateral margins of pereonites 3 and 4 margin bearing 3 elongate setae, distal in mature female rounded in dorsal margin bearing 8 elongate plumose setae. view; lateral margins of pereonites 5–7 Pleopod 2 with peduncle broader than in in mature male rounded or straight or pleopod 1; exopod bearing robust appen- only pereonite 5 strongly angled . . . . 2 2. Pereonite 4 in mature female about dix masculina, basally broader than 1.5 times as wide as pereonite 5; exopod, longer than exopod, tapering to lateral margins of all pereonites of oblique-truncate apex, with groove run- male rounded to slightly angled ning entire length on anterior face; ...... A. sexpes Kensley, 1977 endopod bearing 7 elongate distal plu- – Pereonite 4 in mature female twice as mose setae; exopod with 11 or 12 elongate wide as pereonite 5; lateral margins distal plumose setae. of male pereonite 5 angled ...... 3 Remarks.—Amesopous richardsonae is 3. Pereonite 4 of mature female with a more abundant species than its single high hemispherical boss; pereonites 2 previous collection mentioned in the and 5 of male prominently an- A. gibbosus literature would suggest. It may be re- gled ...... Mu¨ller, 1989 – Pereonite 4 of mature female with stricted to hydroids but has been taken in low ridge divided into longer anterior dredged samples as well as in coral reef and shorter posterior sections; only environments. The species was described pereonite 5 of male prominently initially from pearl oyster beds in the Gulf angled ...... of Manaar, Sri Lanka, but new records ..... A. dakhla Menioui & Poore, 2008 from the African coast of the northern Indian Ocean, Andaman Islands, tropical Arcturinoides angulata, sp. nov. Australia, and Japan considerably expand Figs. 3, 4 the species’ range. Type material.—HOLOTYPE. USNM 253327, male, 4.0 mm, Persian Gulf, Arcturinoides Kensley, 1977 Kuwait Bay, 29u289N, 47u559E, gray clay with shells, Mar 1982 (stn 553). PARA- Arcturinoides Kensley, 1977:241–242. TYPES. USNM 253328, 4 ovigerous Type species.—Arcturinoides sexpes females, 4.0–4.5 mm, 2 males, one juve- Kensley, 1977 (by original designation). nile, same data as holotype; USNM Remarks.—A fourth species of this 253329, 5 males, 8 ovigerous females, 2 distinctive, vaulted rather than cylindri- females, Mar 1982 (stn 353). cal, arcturid genus is reported together Other material examined by BK with new records of the two Indian Ocean and MS.—USNM 253330, 22 males, 26 species previously described. Species of ovigerous females, six females, 17 juve- Arcturinoides have pereopods 2 and 3 niles, from 32 stations in Persian Gulf, without numerous setae and without 1.3–2.3 m, 1981–1982. dactyli, lack pereopod 4, and have a broad Other material examined by GCBP.— maxillipedal palp article 3. NMV J55377, 2 males, 5 females, United Arab Emirates, Umm Al Quwain, Khor Key to species of Arcturinoides Al Beidah, 25u33.709S, 55u37.489E, F. Kennedy, 2007. 1. Lateral margins of pereonites 3 and 4 Diagnosis.—Lateral margins of pereo- in mature female almost parallel- sided in dorsal view, with obtuse nites 3 and 4 in mature female almost angles in front and behind; lateral parallel-sided in dorsal view, with obtuse margins of pereonites 5–7 in mature angles in front and behind; pereonite 4 in male angled, pereonite 5 the widest mature female 1.2 times as wide as ...... A. angulata, sp. nov. pereonite 5, with low middorsal carina. 434 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 3. Arcturinoides angulata. a, b, holotype male in dorsal and lateral views (USNM 253327); c, d, ovigerous female in dorsal and lateral views, scale 5 1.0 mm (USNM 253328); e, maxilliped; f, g, male pleopods 1, 2 (USNM 253327).

Lateral margins of pereonites 5–7 in with low rounded middorsal carina; per- mature male angled, pereonite 5 the eonite 4 with rounded crest-like middorsal widest. carina in anterior half, low rounded Abbreviated description.—Female: Body carinae in posterior half. Oostegite 1 length 2.3 times width at pereonite 4. All membranous, small, rectangular, hidden pereonites laterally obtusely angulate; by others; oostegite 2 membranous, nar- pereonites 3 and 4 widest and parallel row, supported by visible, transversely- sided. All pereonites (except pereonite 4) directed spike-like coxal plate; oostegite 3 VOLUME 120, NUMBER 4 435

Fig. 4. Arcturinoides angulata. a, antennule; b, antenna; c–h, pereopods 1–4, 6, 7; i, uropod (USNM 253327). membranous, half area of oostegite 4, Male: Body 3.3 times longer than width distinct from coxa 4; oostegite 4 chit- of expanded pereonite 5. Cephalon with inised, extending to midline and covering low rounded middorsal carina in posteri- coxa 3. or half. Pereonites 1–3 subequal in width, 436 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON laterally angulate, each with low rounded Zanzibar, 6u129S, 39u069E, Mozambique, middorsal carina; pereonite 4 narrowest, 16 m, coral, N. L. Bruce, 20 Sept 1995. laterally barely angulate; pereonite 5 wid- Diagnosis.—Lateral margins of pereo- est, laterally triangular; pereonites 6 and 7 nites 3 and 4 in mature female rounded in laterally angulate. Pleotelson with two dorsal view; pereonite 4 in mature female ‘shoulders’ on each side indicating pleo- twice as wide as pereonite 5, with high he- nites 1 and 2, apex narrowly rounded, with mispherical boss. Lateral margins of per- low rounded middorsal tripartite carina. eonites 2 and 5 of male prominently angled. Pereonites 3 and 4 usually with broad red- Remarks.—Previously recorded from brown pigmented areas dorsally. the Gulf of Aden at 76 m depth, the Antennule peduncle article 3 almost as species’ range is now extended south, to long as first two together, flagellum of 1 Mozambique, and into shallower water article as long as peduncle article 3, (16 m depth). bearing 3 distal aesthetascs. Antenna peduncle articles 1–3 short, articles 4 and Arcturinoides sexpes Kensley, 1977 5 elongate, cylindrical, each as long as articles 1–3 together; flagellum of 3 Arcturinoides sexpes Kensley, 1977:242, articles plus terminal claw. Pereopod 1 figs.3–5.—Kensley,1978a:22,fig.9A–C. carpus bearing 6 stout bifringed setae on posterior margin, propodus with 3 bi- Material examined.—USNM 253324, 2 fringed setae on posterior margin plus non-ovigerous females, off Mozambique, several more elongate setae on mesial 24u499S, 35u139E, 73 m, Aug 1964 (IIOE surface. Pereopods 2 and 3 lacking dacty- cruise 7, stn 371-G); USNM 253325, 1 lus, remaining articles bearing few elon- ovigerous female, off Mozambique, gate fringed setae. Pereopods 5–7 with few 24u489S, 34u599E, 92 m, 19 Aug 1964 short setae. Pleopod 1 endopod having (IIOE cruise 7, stn 372-B); USNM emargination at about midlength of mesi- 253326, 2 ovigerous females, N of Beira, al margin bearing 2 elongate fringed setae. Mozambique, 19u099S, 36u559E, 88 m, Pleopod 2, appendix masculina robust, Oct 1964 (IIOE cruise 8, stn 403-E). articulating near base of endopod, extend- Diagnosis.—Lateral margins of pereo- ing beyond rami by half its length, apically nites 3 and 4 in mature female rounded in trifid. Uropodal endopod shorter than dorsal view; pereonite 4 in mature female wide, lens-shaped, bearing 3 setae. 1.5 times as wide as pereonite 5, with Remarks.—The differences among the prominent middorsal saddle. Lateral mar- four similar species of Arcturinoides are gins of all pereonites of male rounded to summarized in the key to species above. slightly angled, none especially produced. The description of the oostegites given Remarks.—Originally recorded at 26– above is probably true of all species. 60 m from off Natal, South Africa, the Etymology.—The specific name refers species is now recorded further north in to the angled lateral margins of the Mozambique. pereonites in both males and females. Astacilla Cordiner, 1793 Arcturinoides gibbosus Mu¨ller, 1989 Astacilla.—Sars, 1897:87.—King, 2003b: Arcturinoides gibbosus Mu¨ller, 1989:196– 361. 199, figs. 1–22. Arcturella Sars, 1897:92.

Material examined.—ZMUC CRU- Remarks.—The genera Astacilla and 1891, 1 ovigerous female, Murogo Reef, Arcturella have always been difficult to VOLUME 120, NUMBER 4 437 distinguish. Sars (1897) differentiated A. longispina (Kensley, 1978b) (10.5 Arcturella from Astacilla on the broader mm. Off Natal, South Africa; Mozambi- body and ‘‘less elongated’’ pereopods 2–4, que (Kensley 2001)) but a review of the 46 species assigned to A. mccaini, sp. nov. (7.0 mm. Persian the two genera (Schotte et al. 2005 Gulf, Saudi Arabia) onwards) finds all intermediate forms A. pustulata (Barnard, 1920) (10.0 mm. from extremely narrow to compact forms Off Natal, South Africa) and diverse pereopod shapes. King A. spinicutis, sp. nov. (8.9–9.6 mm. Off (2001), in a phylogenetic analysis, could south-east coast of South Africa) not find characters that would reliably A. tranquilla (Kensley, 1975) (6.3 mm. differentiate the genera. She reported two Still Bay, South Africa) synapomorphies for Astacilla sensu lato: loss of dactyls and flexion between the Astacilla mccaini, sp. nov. carpus and the propodus on pereopods 2– Figs. 5, 6 4 and used these characters to assign A. Type material.—HOLOTYPE. USNM lewtonae to this genus (King 2003b). The 253336, male, 7.0 mm, eastern Manifa two genera are treated as synonymous Bay, 27u309N, 48u549E, Persian Gulf, here, an initiative introduced to this paper Saudi Arabia, seagrass and sand bottom, by the third author. Species of Astacilla 1.3 m, Mar 1982 (stn 5G1). PARA- are variously cylindrical or more or less TYPES. USNM 253337, 7 males, 6.2– flattened, have all pereopods present, 6.5 mm, 9 ovigerous females 7.0–8.5 mm, pereopod 1 with a claw, pereopods 2–4 6 females, 7 juveniles, same data as without dactyls, pereonite 4 elongate, and holotype; USNM 253338, 2 males, 4 the appendix masculina elongate and ovigerous females, 2 juveniles, middle straight. Kensley (1978a) treated all six Manifa Bay, Persian Gulf, Saudi Arabia, southern African species as Arcturella. seagrass and sand bottom, 1.3 m, 20 Nov Species of Astacilla from the Indian 1981 (stn 4G1). Ocean are: Other material examined.—USNM A. amblyura Stebbing, 1905 (9.0 mm. 253339, 55 males, 43 ovigerous females, Gulf of Manaar, Sri Lanka) 12 females, 86 juveniles, from 60 stations A. brevipes (Barnard, 1920) (9.0 mm. in Kuwait Bay, Persian Gulf, 1–3 m, False Bay to Port Elizabeth, South Africa) collected 1981–1982. A. corniger Stebbing, 1873 (12.0 mm. Diagnosis.—Male: Body cylindrical, Saldanha Bay to Port Elizabeth, South lacking ornamentation. Pereonite 4 tubu- Africa) lar, 4.2 times longer than deep. Pleotelson A. eminentia Kensley, 1984 (6.7 mm. longer than 3 preceding pereonites, api- Zululand coast of South Africa) cally narrowly rounded, with two round- A. gibbossa Pillai, 1954 (length not ed ‘shoulders’ on each side. Antennule given. Travancore, India) with flagellum only slightly shorter than 3 A. lewtonae King, 2003b (7.3 mm. NW peduncle articles together, bearing about Western Australia) 16 aesthetascs. Antennal flagellum of 2 A. lineata Stebbing, 1873 (11.0 mm. articles plus apical claw, posterior surface Luderitz, Namibia to East London, of both articles bearing double row of South Africa (Kensley & Schotte 1984)) acute triangular scales. Penial plate nar- A. lobulata (Barnard, 1925) (10.5 mm. rowly rectangular. Pleopod 2, appendix False Bay to Natal, South Africa) masculina articulating near base of en- A. longipes (Barnard, 1920) (10.0 mm. dopod, reaching beyond ramus by 0.6 its Table Bay to Port Elizabeth, South length, tapering distally, consisting of 2 Africa) apically rounded slender structures 438 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 5. Astacilla mccaini. a, b, ovigerous female in dorsal and lateral views, scale 5 2.0 mm (USNM 253337); c, holotype male in lateral view (USNM 253336). sheathed basally. Uropodal endopod rior margin of pereonite 1. Body widest at about half length and width of exopod, anterior of pereonite 4; latter with longi- bearing 2 distal setae. tudinal raised mesial area dorsally, bear- Female: Cephalon with pair of sub- ing strong conical tubercle at midlength, median conical tubercles posterior to and having submedian pair of low tuber- eyes. Median conical tubercle near poste- cles posteriorly. Pereonite 5 having 2 VOLUME 120, NUMBER 4 439

Fig. 6. Astacilla mccaini. a, antennule; b, ventral view of antennal flagellum; c, mandible; d, e, maxillae 1, 2; f, maxilliped; g–i, pereopods 1, 2, 7; j, penial plate; k, l, male pleopods 1, 2; m, uropodal rami (USNM 253336). 440 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON small submedian tubercles near posterior ly, tapering posteriorly, dorsally evenly margin. Pleotelson having grooves ante- rounded, lacking ridges or ornamenta- riorly, marking lines of fusion of pleo- tion. Pereonites 5–7 decreasing in width, nites; with 2 rounded ‘shoulders’ on each with low rounded lateral ridges. Pleotel- side; apex a rounded right-angle. son with single lateral ‘shoulder’, then Remarks.—Two species of Astacilla tapering to narrowly rounded posterior from the northern Indian Ocean most apex. closely resemble the present species. Antennular flagellum bearing 4 aesthe- Astacilla amblyura Stebbing, 1905 from tascs distally. Antennal flagellum of the Gulf of Manaar, has a similar per- terminal claw plus 3 articles bearing row eonite 4 in the female, with a middorsal of triangular scales. conical tubercle. The pleotelson, while Male: Unknown. similar, however, is more slender in A. Remarks.—In the lateral expansion of amblyura, which also possesses a basal the female pereonite 4, Astacilla spinicutis tooth on the proximal fourth antennal resembles none of the wide species pre- peduncle article. This latter feature is viously assigned to Arcturella recorded absent in A. mccaini. Astacilla gibbosus from the east coast of South Africa Pillai, 1954, was not illustrated when (Kensley 1978a). Further, the distinctive described, but Pillai (1954:18) noted that integumental structure of spinules and it closely resembled A. sheardi Hale, 1946, setules differs from that of any of these from South Australia, in the structure of species. the antenna and sculpturing of the body. Etymology.—The specific name is The female of the Australian species is a combination of the Latin ‘spina’, a spine, a narrow, almost cylindrical animal, quite and ‘cutis’, skin, and refers to the finely different from A. mccaini, which has spinulose integument of the exoskeleton. a broad pereonite 4. Astacilla gibbosus presumably would differ from the present Holidoteidae Wa¨gele, 1989 material in the same way. Neoarcturus Barnard, 1914 Etymology.—The species is named for Dr. J. C. McCain, who collected a great Neoarcturus Barnard, 1914:213.—Poore, deal of material in the Persian Gulf. 1991:1.—Poore, 2003:1818–1819.

Astacilla spinicutis, sp. nov. Remarks.—Poore (2003) assigned nine Fig. 7 species of southern African Arcturidae to Type material.—HOLOTYPE. SAM- Holidoteidae and to the genus Neoarc- 43182, ovigerous female 9.6 mm, off turus. The family is endemic to the south-east coast of South Africa, southern African region. Most species 33u30.39S, 27u22.19E, 80 m, 29 May had previously been treated as belonging 1978 (R/V Meiring Naude stn SM-179). to the nomen nudum ‘Microarcturus’,as PARATYPES. SAM-43183, 2 ovigerous for example in Kensley (1978a). The new females (one damaged) 8.9 mm, same species extends the range of the family data as holotype. and genus a little north along the eastern Diagnosis.—Female: Body about 2.4 coast of Africa. times longer than wide, widest at anterior pereonite 4. Entire integument bearing Neoarcturus obesopleon, sp. nov. tiny triangular spinules and short setules. Fig. 8 Cephalon with most of dorsal area Type material.—HOLOTYPE. USNM moderately convex. Pereonites 1–3 later- 253341, male, 7.9 mm, off southern Mo- ally rounded; pereonite 4 widest anterior- zambique, 24u049S, 36u159E, 1610 m, 17 VOLUME 120, NUMBER 4 441

Fig. 7. Astacilla spinicutis. a, b, holotype ovigerous female in dorsal and lateral views, scale 5 2.0 mm; c, antennule; d, antenna (with detail of ornamentation); e, f, left and right mandibles; g, h, maxillae 1, 2; i, maxilliped; j–l, pereopods 1–3 (SAM-43182). 442 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Fig. 8. Neoarcturus obesopleon. a, holotype male in lateral view, scale 5 2.0 mm; b, male pleon in dorsal view (USNM 253341); c, ovigerous female in dorsal view (USNM 253342); d, antennule; e, antenna; f, pereopod 1; g, penial plate; h, i, male pleopods 1, 2 (USNM 253341). VOLUME 120, NUMBER 4 443

Aug 1964 (IIOE stn 369-F). PARATYPE. the swelling is nowhere near as promi- USNM 253342, ovigerous female, 7.8 nent. Males of several species have paired mm, same data as holotype. dorsolateral spines variously developed Diagnosis.—Male: Dorsal cephalon along the pereonites but they are present and pereonites rugose, with scattered tiny only in the female of the new species. rounded tubercles. Eyes lacking. Pereo- Etymology.—The specific name, from nites 2 and 3 subequal in length; pereonite the Latin ‘obesus’, fat or corpulent, plus 4 slightly longer; pereonites 5–7 subequal. pleon, refers to the strongly inflated Pleon consisting of strongly inflated, anterior pleon of the male. globose anterior half with lateral conical spine on each side; posterior half narrower Acknowledgments than anterior, dorsally rounded, apically rounded. Antennular flagellum bearing 11 This work would not have been possible aesthetascs. Penial plate with tips separate without the labors of several collectors. In and diverging, subequal in length to addition to the anonymous collectors of peduncle of pleopod 1. Pleopod 1 bearing the International Indian Ocean Expedi- row of triangular tubercles on lateral tion, we are grateful to the following: Niel margin of peduncle, 5 coupling hooks on Bruce, National Institute of Water and mesial margin; endopod shorter than Atmospheric Research, Wellington, New exopod, with 7 plumose marginal setae; Zealand, who contributed rich collections exopod bearing strong oblique groove on from Zanzibar while employed at the posterior face, with row of simple setae Zoological Museum, Copenhagen; Ste- near lateral margin plus 6 robust fringed phen Grabe and John McCain who setae distally; apex rounded beyond end of collected material in the Persian Gulf off groove, bearing 8 plumose marginal setae. Kuwait and Saudi Arabia during the Pleopod 2, appendix masculina articulat- course of environmental studies; Michelle ing basally on endopod, tapering distally, van der Merwe of the South African with setule-lined groove. Museum, who made material available Female: Dorsum of cephalon, pereo- on loan. We wish to acknowledge with nites, and anterior pleon rugose/tubercu- thanks the assistance given to Niel Bruce late. Cephalon with deep lateral notch, in the field by Matt Richmond and the line of fusion with pereonite 1 marked by generous provision of facilities by the lateral notch and dorsal groove. Pereonite Institute of Marine Sciences, University 1 weakly anterolaterally expanded. Per- of Dar es Salaam at Zanzibar. Additional eonites 2 and 3 subequal in length, material from the United Arab Emirates anterolaterally expanded as rectangular was made available to GCBP by Fergus plate where body is widest. Dorsolateral Kennedy, Lewes, UK. GCBP thanks the margins of cephalon and pereonites 1–4 first two authors for the opportunity to with acute paired processes. Pereonites 5– complete this work. 7 subsimilar but decreasing in length and width posteriorly. Pleon not inflated anteriorly, posterior half dorsally round- Literature Cited ed; apex rounded. Barnard, K. H. 1914. Contributions to the crusta- Remarks.—Of the nine southern Afri- cean fauna of South Africa. 1. Additions to can species of Neoarcturus figured and the marine Isopoda.—Annals of the South keyed by Poore (2003), N. obesopleon African Museum 10:197–230. ———. 1920. Contributions to the crustacean fauna most resembles N. kensleyi Poore, 2003, of South Africa. No. 6. Further additions to the only species where a swollen anterior the list of marine Isopoda.—Annals of the pleotelson is known. But in that species South African Museum 17:319–438. 444 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

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