Cystisoma fabricii Stebbing

Zeidler, Wolfgang, 2003, A review of the hyperiidean amphipod family Cystisomatidae Willemöes­Suhm, 1875 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 141, pp. 1-43 : 19-25

Cystisoma fabricii Stebbing ( Figs 7 & 8 )

Cystisoma fabricii Stebbing, 1888: 1333 ­1334. – Barnard 1932: 272 ­273. Hurley 1956: 10. Brusca 1967a: 387. Brusca 1967b: 451. Brusca 1973: 9 (Table), 13. Lorz & Pearcy 1975: 1444 (Table). Brusca 1981a: 19 (key), 39, fig. 5c, e. Brusca 1981b: 358 ­375, figs 2­15. Vinogradov et al. 1982: 251 ­252, fig. 123. Vinogradov 1990: 57. Vinogradov 1999: 1176, fig. 4.71.

Thaumatops fabricii – Woltereck 1903: 457. Stephensen 1918: 63 ­64, figs 22, 23. Schellenberg 1927: 623, figs 32, 33. Pirlot 1929: 89.

Thaumatops loveni Bovallius, 1886: 10 ­13, figs 1­14. – Bovallius 1887a: 15. Bovallius 1889: 52 ­ 58, pl. 4, figs 1­25. Stephensen 1918: 59.

Thaumatops coalita Woltereck, 1903: 458 , fig. 4.

Cystisoma coalitum – Siegfried 1963: 6 (list). Dick 1970: 55.

Cystisoma spinosum [misidentification] – Stebbing 1888: 1330 ­1331, pl. 156 (spec. D).

Type material

The unique type, a female measuring about 65 mm, is in the BMNH (1889.5.15.199). Stebbing (1888) originally described this species, referring to it as “ Cystisoma . Specimen G”, and proposed the name C. fabricii “should it be thought necessary to make this a separate species”. Although Stebbing gives no illustrations, the absence of oral spines readily distinguished it from all its congeners, and thus it has been recognised as a valid species by subsequent authors. The type locality is “off the Meangis Islands, north of Papua ”, due south of Mindanao, the Philippines, 4°33’N, 127°6’E; depth, 500 fathoms, trawled. (Challenger Stn. 214).

Type material of synonyms

The unique type of C. lovenii , a female measuring about 105 mm, appears lost. Stephensen (1918: 59) made a search for it in the ZMUC and all likely museums in Sweden without success. A recent search of the ZMUC and SMNH collections was also unsuccessful. The specimen figured by Bovallius (1886) is obviously a female, as the brood plates are clearly illustrated and the morphology of pereopod 7 is that of a mature female. As suggested by Stephensen (1918), Bovallius is wrong regarding pereonites 1 and 2 separate, as he had made this error with C. longipes . The mandible figured by Bovallius (1886, fig. 3) is most likely the second maxilliped, or part of the lower lip. He correctly illustrates the mandible later in his monograph ( Bovallius 1889, pl. 4, fig. 4). It appears to have only one spine medially, although this is not clearly evident from his illustration. Regarding the presence of oral spines, Bovallius says “on the underside of the head there is no shorter row of spines as in Th. neptunus and Th. pellucida ”. This character, combined with the single mandibular spine, and the relatively short first antennae, confirms that C. lovenii is the same as C. fabricii . Although Bovallius’s species has priority, it has not been mentioned in the literature since Stephensen (1918), and the type is lost. Cystisoma fabricii however, is a well­established, readily recognisable species. Consistent with nomenclatural stability Stebbing’s (1888) name should continue to be used for this species ( ICZN, article 79c amended).

The types of C. coalita , a female less than 40 mm long and four males measuring 26, 27, 32 and 40 mm, could not be found at the ZMB or ZMH and are presumed lost. The ventral spines consist of only one large anterior spine and the glandular spine. Oral spines are absent, and the first antennae are subequal in length to the head. The latter two characters apply only to C. fabricii . The fusion of pereonites is an unreliable character as the sutures are often difficult to see in all but adult specimens. Also, juveniles tend to have more anterior pereonites fused. Amongst the material examined was a larva (13 mm) with pereonites 1­5 fused, and juveniles of C. fabricii (25­30 mm) with pereonites 1­3 fused. Thus, Cystisoma coalita should be considered a synonym of C. fabricii .

Material examined (234 specimens)

Types. Holotype female of C. fabricii , approximately 65 mm: in spirit, damaged.

Other material examined. North Atlantic: 5 lots ( BMNH), 27 lots ( ZMUC), 54 specimens. South Atlantic: 2 lots ( BMNH), 2 lots ( SAM), 12 lots ( ZMUC), 20 specimens. North Indian: 9 lots ( ZMUC), 17 specimens. South Indian: 1 lot ( SAM), 6 lots ( ZMUC), 15 specimens. Central Indo­Pacific: 1 lot ( USNM), 23 lots ( ZMUC), 43 specimens. North Pacific: 3 lots ( CAS), 20 lots ( LACM), 5 lots ( SAMA), 9 lots ( USNM), 5 lots ( ZMUC), 56 specimens. South Pacific: 1 lot ( BMNH), 7 lots ( USNM), 8 lots ( ZMUC), 21 specimens. Tasman Sea: 3 lots ( ZMUC), 7 specimens.

Diagnosis

Body length of females up to 90 mm; of males up to 50 mm. Head as long as deep; almost as long as first six pereonites combined; oval when viewed laterally, with evenly convex anterior margin when viewed dorsally. Marginal spines 10­14; anterior ventral spine larger than glandular spine, clearly the largest; oral spines absent. Eyes oval, barely separated medially. First antennae subequal in length to head, with one small terminal article. Mandibles with only one medial tooth. Pereopod 5; carpus distinctly shorter than propodus. Urosome (with uropods) slightly shorter than pleon. Uropod 1; exopod subequal in length to endopod, about 0.3­0.4x length of peduncle. Uropod 3 similar to U1, exopod length 0.4­0.5x peduncle.

Remarks

This species is readily distinguished by the lack of oral spines, a character shared only with C. gershwinae sp. nov., but in that species the first antennae are considerably longer than the head. The anterior spine of C. fabricii is much larger than the glandular spine (A2), and usually relatively larger than found in other species.

In all of the material examined the carpus of pereopod 5 is distinctly shorter than the propodus, a character only shared with C. pellucida . In all other species these articles are subequal in length, or the propodus is slightly shorter than the carpus.

One specimen, a female measuring 66 mm (SAM A42204), has mandibles with a small tooth adjacent to the main medial one. It seems to be an abnormality of the medial tooth rather than an undeveloped lateral tooth. Lateral mandibular teeth are clearly absent in this species.

According to water­colour drawings and colour notes made from living material by Stephensen, the specimens are colourless, except for articles 4 and 5 of pereopod 4, and articles 4­6 of pereopods 5­7, which are pink/red at the margins.

Cystisoma fabricii is an unusual species in that males seem to reach only half the maximum size of females.

Distribution

This species is found in the tropical and temperate regions of the Atlantic Ocean, the tropical part of the Indian Ocean and mainly in the tropical parts of the Pacific Ocean, including the Tasman Sea. It is relatively common off southern California where it is the most common species of Cystisoma ( Brusca 1981b) .

Cystisoma magna (Woltereck) ( Fig . 9)

Thaumatops magna Woltereck, 1903: 454 ­455, figs 2, 3. – Spandl 1927: 171 ­172, figs 8, 9a­d. Cystisoma magna – Vinogradov et al. 1982: 248 ­250, fig. 122; Vinogradov 1990: 57. Cystisoma spinosum [misidentification] – Stebbing 1888: 1319 ­1325, pl. 154 (spec. A), 1331­1332

(spec. E).

Cystisoma pellucidum [misidentification] – Barnard 1932: 272 (spec. 2, 3, 5).

Type material

The two syntypes of C. magna , both females measuring about 80 mm (?) and 120 mm (photographed), could not be found at the ZMB or ZMH and are presumed lost. Despite the limited description and figures, the combined characteristic features of relatively short antennae, presence of oral spines (3), and mandibles with only one tooth, readily distinguish this species from all its congeners. The type locality is the tropical Indian Ocean, just west of the Cocos Islands, 10°8’S, 97°15’E ( Valdivia Stn. 182) and near the Seychelles, 4°35’S, 53°43’E ( Valdivia Stn. 235). The latter is the locality of the specimen figured by Woltereck.

Material examined (134 specimens)

North Atlantic: 4 lots ( BMNH), 4 lots ( USNM), 8 lots ( ZMUC), 20 specimens. South Atlantic: 1 lot ( BMNH), 1 lot ( ZMB), 5 lots ( ZMUC), 9 specimens. North Indian: 8 lots ( ZMUC), 13 specimens. South Indian: 2 lots ( SAM), 24 lots ( ZMUC), 51 specimens. Central Indo­Pacific: 4 lots ( ZMUC), 7 specimens. North Pacific: 1 lot ( BMNH), 2 lots ( CAS), 4 lots ( LACM), 9 lots ( USNM), 4 lots ( ZMUC), 23 specimens. South Pacific: 6 lots ( ZMUC), 10 specimens. Tasman Sea: 1 lot ( ZMUC), 1 specimen.

Diagnosis

Body length of females up to 140 mm, of males up to 90 mm. Head as long as deep; as long as first 5.5 pereonites combined; oval when viewed laterally, with evenly convex anterior margin when viewed dorsally. Marginal spines 12­14; anterior ventral spine larger than glandular spine, clearly the largest; oral spines 2­4. Eyes oval, barely separated medially. First antennae only about half as long as head, with one small terminal article. Mandibles with only one medial tooth. Urosome (with uropods) slightly shorter than pleon. Uropod 1; exopod marginally shorter than endopod, about 0.3x length of peduncle. Uropod 3; exopod subequal in length to endopod, slightly less than half­length of peduncle.

Remarks

This is the largest species of Cystisoma , readily distinguished by the short first antennae, which are relatively shorter than in any other species. One of the Challenger specimens (specimen E, BMNH 1889.5.15.196), a juvenile male measuring 42 mm, has first antennae slightly longer than the head but all other characters are consistent with C. magna . Similarly, three of the nineteen males from the Dana collections have first antennae slightly longer than the head. Perhaps juvenile specimens have relatively longer first antennae as in C. longipes ?

Cystisoma magna also differs from all other species in that the peduncle of uropod 1 is relatively longer, being about three times as long as the exopod.

Shoemaker (1945) recorded 15 specimens from Bermuda but an examination of this material proved that they are all C. longipes .

Distribution

This species is known from a few scattered records from the warm waters of the Indian, Atlantic and Pacific Oceans. It is also found off the southeast coast of South Africa.

Figures

FIGURE 8. Cystisoma fabricii, North Pacific, USNM. Female, 53 mm. A, lateral view. Scale bars = 5.0 mm (A), 1.0 mm (G 1 & 2).

FIGURE 9. Cystisoma magna, North Pacific, USNM. Female, 110 mm. Scale bars = 2.0 mm (Md), 5.0 mm (remainder).