Cystisoma latipes (Stephensen)

Zeidler, Wolfgang, 2003, A review of the hyperiidean amphipod family Cystisomatidae Willemöes­Suhm, 1875 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 141, pp. 1-43 : 27-37

Cystisoma latipes (Stephensen) ( Figs 10­13)

Thaumatops latipes Stephensen, 1918: 62 ­63, fig. 21. – Schellenberg 1927: 621, fig. 29.

Cystisoma latipes – Pirlot 1938: 377, 379, 380, 384, 386. Pirlot 1939: 34. Brusca 1973: 9 (Table), 14. Brusca 1981a: 19 (key), 39, fig. 5d. Brusca 1981b: 358, fig. 12c. Vinogradov et al. 1982: 254 ­255, fig. 125.

? Cystisoma parkinsonii Stebbing, 1888: 1332 ­1333.

? Thaumatops parkinsonii – Stephensen 1918: 66 ­68, figs 28, 29. Schellenberg 1927: 623, fig. 32.

? Thaumatops longipes [misidentification] – Bovallius 1887b: 558. Bovallius 1889: 47 ­52 (spec. B, non A).

Type material

The unique type of C. latipes , a male measuring 44 mm, is in the ZMUC ( CRU 2828). The type locality is the North Atlantic Ocean, south of Ireland, 49°22’N, 12°52’W ( Thor Stn. 81), 1350 m.

Type material of synonyms

The unique type of C. parkinsonii , a male measuring about 50 mm, is in the BMNH (1889.5.15.198). Stebbing (1888) originally described this species, referring to it as “ Cystisoma . Specimen F”, and proposed the name C. parkinsonii “if, in view of the great length of the upper antennae, it be necessary to separate this specimen from the others”. The specimen is very similar to C. latipes , differing in having slightly shorter first antennae, mandibles with only a medial tooth, and the basis of pereopod 7 slightly narrower but still relatively inflated proximally. Despite these differences, it appears to be the same as C. latipes , although the length of the first antennae could not be determined accurately, because the specimen is in pieces. Amongst the material examined there are other specimens of C. latipes with mandibles without lateral teeth and the basis of pereopod 7 relatively inflated proximally, compared to other species.

Material examined (56 specimens)

Types. Holotype male of C. latipes , approx. 44 mm: in spirit. Holotype male of C. parkinsonii , approx. 50 mm, specimen “F”, Challenger Stn. 196, north of Amboina, 0°48’30”S, 126°58’30”E, trawled 825 fathoms, 13th October, 1874: 3 microscope slides of head, mouthparts, Us, A1, G1 & 2 and P3­7 from right; remainder in spirit.

Other material examined. North Atlantic: 8 lots ( ZMUC), 1 lot ( USNM), 9 specimens. South Atlantic: 1 lot ( SAM), 2 lots ( ZMUC), 3 specimens. North Indian: 1 lot ( ZMUC), 1 specimen. South Indian: 1 lot ( SAM), 10 lots ( ZMUC), 12 specimens. Central Indo ­Pacific: 2 lots ( ZMUC), 2 specimens. North Pacific: 2 lots ( CAS), 1 lot ( LACM), 2 lots ( USNM), 5 specimens. South Pacific: 2 lots ( ZMUC), 2 specimens.

Diagnosis (males only)

Body length up to 50 mm. Head as long as depth posteriorly; as long as first 4.5 pereonites combined; wedge­shaped when viewed laterally, with slightly concave anterior margin when viewed dorsally. Marginal spines 14­15; anterior ventral spine sometimes smaller than glandular spine; oral spines 2­4. Eyes obliquely­oval, barely touching anteriorly, and widely separated posteriorly. First antennae as long as head and pereon combined, with one small terminal article, medial surface with dense brush of aesthestascs, slightly inflated proximally. Mandibles with one medial tooth and one lateral tooth (absent in some specimens). Pereopod 7 with pear­shaped basis, inflated proximally, maximum width about half­length, or 4x width, near distal margin. Urosome (with uropods) slightly shorter than pleon. Uropod 1; exopod subequal in length to endopod, about 0.4x length of peduncle. Uropod 3 similar to U1, exopod length slightly more than half­length of peduncle.

Female unknown.

Remarks

Unusual characters of this species are the relatively long first antennae with aesthestascs, and the wedge­shaped head. In all other species of Cystisoma the head is more oval and, except for C. gershwinae sp. nov., the first antennae are without a brush of aesthestascs medially. The eye shape is also unusual, and the eyes occupy less of the lateral part of the head than other species, suggesting that this species may inhabit deeper water than its congeners.

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 four, articles 2­6 of pereopods 5­7 and the first uropods, all of which are pink/red at the margins.

Some specimens examined have all the characters of C. latipes except that the mandibles lack lateral teeth (e.g. USNM 39002). In this respect they are similar to the specimen described as C. parkinsonii by Stebbing (1888) ( Fig. 12 ). Thus, it would seem that the presence or absence of a lateral mandibular tooth is variable in C. latipes . As these specimens are slightly larger than the type this character is not size dependent.

Amongst the material from the ZMUC, which was seen by Stephensen (1918), are three specimens with relatively long first antennae that are tentatively assigned to C. latipes . The first of these (ZMUC CRU 2838), described by Stephensen as Thaumatops bovalli (= C. longipes ), is a male measuring 46 mm from Thor Stn. 73. This specimen differs from C. latipes in having slightly shorter first antennae without aesthestascs, and pereopod 7 with a narrower basis. The medial surface of the first antennae has a broad white band, which may represent developing aesthestascs. It is possible that this is a recently moulted specimen in which the aesthestascs have not yet developed (as found in other species of hyperiideans), and the basis of pereopod 7 has not differentiated. A second specimen (ZMUC CRU 2833), described by Stephensen (1918) as Thaumatops parkinsonii , is a juvenile male measuring 38 mm from Thor Stn. 72. It is very similar to the previous specimen but the mandibles lack a lateral tooth. The third specimen (ZMUC CRU 2834) is Bovallius’ (1887b) “ type ” specimen B of C. longipes ( Fig. 13 ), which Stephensen (1918) also refers to T. parkinsonii . This specimen, measuring 46 mm, seems to be a juvenile female with developing brood plates. Both Stephensen (1918) and Bovallius (1889) refer to it as a male, probably because pereonite 7 appears to have a pair of gonopores. However, the presence or absence of testes could not be determined as the specimen is in poor condition. It differs from C. latipes in that the mandibles lack lateral teeth and pereopod 7 has a narrow basis. In many respects it is similar to the type of C. parkinsonii , particularly in the generally more slender uropods and in the relatively longer exopods, which are clearly longer than the endopods. This may be a female character of this species. If this specimen is C. latipes then it is the only confirmed female specimen of the species. The type of C. parkinsonii was re­examined but the sex could not be confirmed from the remains.

Distribution

Previously known only from the North Atlantic. Now also known from scattered records from the warm waters of the Indian and Pacific Oceans.

Cystisoma gershwinae sp. nov. ( Figs 14 & 15)

Material examined (14 specimens)

Types. Holotype. Male, 43 mm ( USNM cat. 266786). Off Queen Charlotte Islands, British Columbia, Canada, 51°57’N, 131°05’W, 0­360 m, Halibut Commission, University of Washington, M.H. Pettibone: in spirit.

Paratypes. 1. Male, approx. 53 mm (urosome missing) (USNM cat. 266788). Baja California, Mexico, 39°00’N, 121°00’W to 29°39’N, 121°00’W, mid­water trawl 1140 fathoms, R. Wisner & Parby, 27 April 1951: in spirit. 2. Male, approx. 53 mm (SAMA C5906). San Clemente Basin, California, 500­1000m, IKMT, A. Collins, December, 1997: in spirit. 3. Male, 40 mm (LACM CR 15000057). Locality data uncertain, given as “8346” but is possibly off southern California. 4. Male, 40 mm (ZMUC CRU 3728). Equatorial North Atlantic between Africa and South America, 12°11’N, 32°49’E (Dana Stn. 1165), 1000 MW, 9 September 1921: in spirit. 5. Male, 45 mm (ZMUC CRU 3729). Equatorial North Atlantic between Africa and South America, 10°16’N, 40°41’W (Dana Stn. 1166), 1000 MW, 11 September 1921: in spirit.

Other material. Six males, 35­45 mm, in poor condition, collected by the Dana ( ZMUC CRU 3730­3735) from the equatorial North Atlantic (Stn. 1163), Banda Sea (Stn. 3677), western North Pacific (Stn. 3751) and the eastern North Indian Ocean (Stns. 3902 & 3903). Also, two males in very poor condition, collected by the Galathea ( ZMUC), from the Celebes Sea (Stn. 448) and the western tropical Indian Ocean (Stn. 241).

Diagnosis (males only)

Body length up to 53 mm. Head as long as depth; as long as first 5 pereonites combined; oval when viewed laterally, with straight anterior margin when viewed dorsally. Marginal spines 11; anterior ventral spine shorter than, or subequal to, glandular spine; oral spines absent. Eyes oval, barely separated medially. First antennae slightly longer than head and pereon combined, with one tiny terminal article, medial surface with dense brush of aesthestascs. Mandibles with one medial tooth, lateral teeth absent. Pereopod 7 with basis slightly inflated proximally. Urosome (with uropods) about as long as pleon. Uropod 1; exopod slightly shorter than endopod, slightly less than half­length of peduncle. Uropod 3 similar to U1, exopod length almost half­length of peduncle.

Female unknown.

Description of holotype male

Body length 43 mm. Head as long as deep; as long as first 5 pereonites combined; oval laterally, with relatively straight anterior margin when viewed dorsally. Marginal spines 11, the anterior one the largest. Anterior ventral spine slightly shorter than glandular spine. Oral spines absent. Eyes oval, barely separated medially. First antennae as long as head, pereon and first 1.5 pleonites combined, with tiny terminal article, medial surface with dense brush of aesthestascs. Mandibles with one medial tooth, lateral teeth absent.

Gnathopod 1, relatively small, length slightly more than half G2, about 0.2x P3; distinctly chelate; basis about as long as remaining articles combined. Gnathopod 2, similar to G1, also relatively small, length about 0.4x P3; basis slightly longer than remaining articles combined. Pereopod 3, about half as long as P5; basis to propodus with denticulate posterior margin, denticles on propodus very small; merus, carpus and proximal half of propodus with transverse rows of setae, mainly medially; basis about as long as merus and carpus combined; carpus slightly longer than merus; propodus slightly shorter than carpus but slightly longer than merus. Pereopod 4, as long as 1.5x P3 and 0.7x P5; ornamentation similar to P3 but merus with less, and propodus with more, rows of setae; basis slightly shorter than merus and carpus combined; carpus length about 1.3x merus, slightly shorter than propodus. Pereopod 5 is the longest pereopod; basis to propodus with denticulate anterior margin, denticles on propodus very small; basis to carpus also with row of denticles posteriorly; basis only slightly longer than carpus; merus length nearly 0.7x basis; propodus slightly longer than basis. Pereopod 6, similar to P5, length about 0.8x P5; basis slightly longer than carpus; merus length nearly 0.6x basis; propodus slightly longer than carpus but shorter than basis. Pereopod 7; length slightly less than half P5; basis to propodus with denticulate anterior margin, denticles on propodus smaller; basis and merus also with row of denticles posteriorly; basis pear­shaped, maximum width proximally almost 3x width near distal margin, 0.4x length; basis as long as merus and carpus combined; merus marginally longer than carpus; carpus with fringe of long setae along distal margin; propodus slightly longer than carpus, with transverse rows of setae medially and along distal margin; distal margin concave with anterior tooth; dactylus curved, closing against distal margin of propodus, slightly longer than width of propodus.

Urosome (with uropods) subequal in length to pleon. Uropod 1; peduncle length about 3x maximum width; exopod slightly shorter than endopod, slightly less than halflength of peduncle. Uropod 3; peduncle length about 3x maximum width, about 0.8x length of peduncle of U1; exopod subequal in length to endopod, almost half­length of peduncle. Telson very small, U­shaped, about 0.3x as long as third pleonite.

Etymology

Named for Lisa­ann Gershwin, Department of Integrative Biology, University of California, Berkeley, USA, for her continuous support and encouragement in my research of hyperiideans and for being responsible for locating paratype 2 of this unusual species.

Remarks

The paratypes are like the holotype, except for paratype 1, which has the urosome missing, and slightly shorter first antennae (as long as head and pereon combined), and anterior ventral spines slightly larger than the glandular spines. The first antennae of Paratype 4 are similarly relatively shorter than for the holotype.

The non­type material exhibits the characteristic features of the holotype (viz. the oral and mandibular spines, long first antennae and pereopod 7 with an inflated basis) but have not been designated paratypes because of their poor condition.

The distal margin of the propodus of pereopod 7 is similar in shape to that found in juvenile females of other species. However, the holotype, paratypes and the other specimens are clearly males, as they have distinct testes, and, or lack the developing brood plates usually found in females of a similar size.

The combination of characters of long first antennae with aesthestascs, the absence of oral spines, mandibles lacking lateral spines, and pereopod 7 with a pear­shaped basis, and subchelate propodus and dactylus, readily distinguish this species from all its congeners. Cystisoma gershwinae resembles C. latipes in the length of the first antennae, which have aesthestascs, and the shape of the basis of pereopod 7. It differs from C. latipes mainly in lacking an arched row of oral spines, a character that is only shared with C. fabricii . The shape of the head and eyes is also more like other congeners than C. latipes .

Distribution

This species has been collected from off Queen Charlotte Islands, British Columbia, Canada, the San Clemente Basin, California, Baja California, Mexico and from the equatorial North Atlantic (type material). Other specimens assigned to this species (non­types) have, in addition, been collected from the western North Pacific, the central Indo­Pacific region and the tropical eastern and western Indian Ocean. This species probably occurs in other regions of the world’s oceans, having been mistaken for C. latipes .

Figures

FIGURE 12. Cystisoma latipes, Philippines, BMNH 1889.5. 15.198. Holotype male of C. parkinsoni Stebbing, 1888, male, approx. 50 mm. A, mandibles and oral spines. Scale bars = 5.0 mm (P 3 ­ 7, Us), 0.1 mm (G 1 & 2, Md).

FIGURE 13.? Cystisoma latipes, North Atlantic, ZMUC CRU 2834. Female, 46 mm. Scale bar = 2.0 mm.

FIGURE 14. Cystisoma gershwinae sp. nov., North Pacific, off Queen Charlotte Island, USNM Cat. 266786. Holotype male, 43 mm. A, lateral view; B, mandibles and oral spines. Scale bars = 5.0 mm (A), 2.0 mm (Us), 1.0 mm (B, G 1 & 2).