Collocherides astroboae n. gen., n. sp., a siphonostome

cyclopoid copepod living in the stomach of basket stars

by

Jan H. Stock

Institute of Taxonomie Zoology (Zoölogisch Museum), University of Amsterdam, The Netherlands

which is reduced Abstract segment in the exopod of A 2,

The which created for the to a seta; of "hooks" new Collocherides, is single (2) presence strong

of C. astroboae is related reception n. sp., closely to at the distal end of the caudal ramus; (3) the

Collocheres. Whereas the of Collocheres all are, chaetotaxis formula of 11-2-2 in the 3rd exopod as far as we know, ectoparasites of , Collo- 1 in the segment of P (111-2-3 Collocheres); (4) cherides was found endoparasitic in basket stars (Astro- chaetotaxis formula of 111-I-3 in the 3rd boa nuda, A. albatrossi) at Eilat (Israel), in the Dahlak exopod the Archipelago (Ethiopia), and in Indonesia. segment of P 3 (111-I-4 in Collocheres); (5)

reduction in length of all but one furcal setae, and

INTRODUCTION the absence of plumosity thereon; (6) the ovate

of the distal of P 5 (linear in Col- In the stomach of basket shape segment tropical stars of the genus locheres). Astroboa, small siphonostome cyclopoid copepods C. astroboae be Monotypic; type species n. sp.; en- can found, which always are undigested and in basket stars. thus doparasitic apparently are parasites of the .

For the material avail- present description, was Collocherides astroboae n. sp. able from three localities as far apart as Israel,

Synonymy. — "Cyclopoid copepods"; Tsurnamal Ethiopia, and Indonesia, and from two different & Marder, 1966: 15. hosts, and A. albatrossi. All this

material proved to be a single species, belonging

Material examined. — 23 9,6 $. In the stomach of the to family Asterocheridae, and apparently re- Astroboa nuda (Lyman). Eilat, 8—9 June 1965, M. Tsur- lated to the genus Collocheres. Certain morpholo- namal coll. From this sample 1 9 (holotype), 1 $ (para- features of which reductions gical (all or adapta- type) and 16 9 and 5 $ (paratypes) have been deposited

tions, no doubt under influence of the endopara- in the Zoölogisch Museum Amsterdam (cat. no. Co. 101.090 a-b); another six all in the Depart- sitic mode life of the paratypes, 9, of present form), make it ment of Zoology of the Hebrew University, Jerusalem. advisable to isolate the parasites of Astroboa in More than 100 specimens, of both sexes, from the

a special genus, closely related to, but not identical stomach of 1 specimen of A. nuda, southwestern end of

with Collocheres. Not for all seven species attri- the island of Umm Aabak, Dahlak Archipelago, Ethio-

pia, depth about 50 cm, 23 March 1962, J. H. Stock coll. buted to Collocheres the host is precisely known, Preserved in the Zoölogisch Museum Amsterdam (cat. but four it is known the for, were always ecto- no. Co. 101.091). associates of crinoids or brittle stars (Stock, 1966). 16 9, 9 3» from the stomach of 1 specimen of the form is internal Although present an parasite, Astroboa albatrossi Döderlein, Indonesia, precise locality

its host not sure but Java Sea, 26 June 1926. preference is the same as that for Collo- quite probably Preserved in the Museum Amsterdam cheres. Zoölogisch (cat.

no. Co. 101.092 a-b).

DESCRIPTIVE PART

Description. — Female. Total length (excluding

based 10 fureal setae) 564—628 (mean, on speci- Collocherides ju. n. gen. mens, 606 /x); greatest width, at the level of the

Asterocheridae. Close to but 177—193 183 The Collocheres, differing cephalosome, ju. (mean /<,). body in the absence from the wider following features: (1) of a free (fig. la) gradually tapers cephalo- - 20 ]. H. STOCK COLLOCHERIDES ASTROBOAE N. GEN., N. SP.

1. Collocherides astroboae from Eilat. dorsal of Fig. n. gen., n. sp., a, female, (scale I); b, posterior portion d, anterior mandible, urosome with caudal rami, ￿, ventral (II); c, urosome, ￿. ventral (III); antenna, ￿ (III); e,

(IV); f, anterior maxilla, ￿ (IV).

cuticular the of which some into the narrower anal segment. The first spiniform projections, larger

is curved inward. The lateral furcal arises not pedigerous segment is fully incorporated in the seta

The is far from the distal end of the it is, like the cephalosome. genital segment slightly swol- ramus;

seta len at the level of the genital openings. Ventrally, 4 terminal setae, smooth. A smooth dorsal the base of the robust furcal seta. urosome segments 2, 3, and 4 are ornamented arises near the most with minute cuticular The 1 either the left spines : 2 on segment 2, 6 female bears only egg. on this on segment 3, 2 on segment 4. Segment 5 (= the or on the right side of the body; large, ovate

bears 163 la). anal segment) 2 larger and 1 smaller spinule egg, measures 84—116 X —184 /a (fig.

either side is at (fig. lb). The caudal ramus (fig. lb) The anterior antenna (fig. Id) 20-segmented. is —measured its lateral —41 All bear 2 setae, for segments 1 along margin /i long segments except and 14 wide. it is with 2 9 10 seta 1 spine), 18 p. Terminally, provided (1 seta), (6 setae), (1 + BIJDRAGEN TOT DE DIERKUNDE, 41 (1) - 1971 21

2. Collocherides astroboae from Eilat. anterior Fig. n. gen., n. sp., a, antenna. ￿ (scale III); b, posterior antenna.

fifth ￿ (IV); c. posterior maxilla, ￿ (IV); d, maxilliped, ￿ (V); e, leg, ￿ (IV).

(3 setae -(- 1 aesthete), and 20 (7 setae). The distalmost segment has a slightly widened

The posterior antenna (fig. 2b) consists of a 2- recurved tip.

segmented protopod and a 2-segmented endopod; The legs 1 to 4 are biramous, each ramus being

the latter bears some setules along its lateral mar- 3-segmented (figs. 3a-d). Intercoxal plates are

slender The bear gin and is distally provided with a claw, present. basipods a lateral setule, the

hooked in unarmed. The which shows up (as the figure) in some coxopods are endopods slightly slides, or straight with a slight swelling on the overreach the exopods, and are provided with spi-

niform place where the bent was in other slides. The exo- projections of some importance on seg-

is in the 2 and 3. The chaetotaxis is pod reduced to a heavily sclerotized place ments formula as chitin, at the base of which 1 setule is borne. follows (elements in parentheses are rudimentary):

The oral cone is short, broadly pear-shaped. I The exp. —(1); I—1; II —2 —2 mandible (fig. le) has a robust, tapering f P 1 {

armed with teeth. The is — stylet, distally 6 "palp" [ end. 0 —(1); 0 2; 1—2 — 3

well-developed: its unique segment bears a long, I— I— III exp. 1; 1; —I —4 thick seta that overreaches the mandibular stylet. f P 2 {

The anterior maxilla has — — — — (fig. If) a narrow \ end. 0 1; 0 2; 1 2 3

outer lobe, armed with 1 seta and 1 spinule, and ( I— I— III —I —3 much exp. 1; 1; a wider and shorter inner lobe, armed with P 3 {

terminal setae. — 4 ( end. 0— 1; 0 2; 1—1 — 3

The posterior maxilla (fig. 2c) has an unarmed I— —3 and the of ( exp. 1; I— I; III —I basal segment a 2-segmented claw, tip P 4 Î which is truncated. [ end. 0—1; 0 — 2; 1—1— 2

The maxilliped (fig. 2d) consists of a 2-segment-

basal wide ed portion, and of a 4-segmented claw por- The fifth leg (fig. 2e) consists of a basal

lateral and tion. segment bearing 1 seta a large, triangu- 22 J. H. STOCK - COLLOCHERIDES ASTROBOAE N. GEN., N. SP,

lar, medial lobe, ciliated at both free margins.

ciliated The terminal segment is laterally and

bears 1 lateral, 2 terminal, and 1 medial setae.

Male. 499—531 515 based on Length jn (mean /i,

6 width 145—161 specimens); greatest /x (mean

152 fj.). Urosome 6-segmented (fig. lc); genital

with lobes" P segment "genital (= transformed 6),

of and frame armed consisting chitinous plates a

with 1 spine. The post-genital segments are orna-

mented with 8, 6, 2, and 4 cuticular spinules, re-

spectively. Caudal rami as in female. The only ap-

pendages showing secondary sexual differences are

the anterior antenna and the fifth leg.

The anterior antenna (fig. 2a) is 18-segmented.

The long aesthete is borne on segment 17.

in fe- The fifth leg (fig. lc) is 2-segmented, as

the that of fe- male; basal segment resembles the

male, but the distal segment is narrow at the base, lobe 3 lateral expanding into a rounded bearing

setae and 2 medial feather-shaped spines.

Colour. — Body and eggs are colourless.

REFERENCES

Stock, J. H., 1966. On Collocheres Canu, 1893, and

of Leptomyzon Sars, 1915, two synonymous genera

Copepoda. Beaufortia, 13 (163) : 221 —239.

3. Collocherides astroboae from Eilat. M. & J. 1966. Observations the Fig. n. gen., n. sp., Tsurnamal, Marder, on

first second third star Astroboa nuda coral reefs at a, leg, ￿ ; b, leg, ￿ ; c, leg, ￿ ; d, fourth basket (Lyman) on leg, ￿ (all scale III). Elat (Gulf of Aqaba). Israel J. Zool., 15 : 9—17.

Received: 2 June 1970