GNATHOPHYLLID SHRIMP OF THE HAWAIIAN ISLANDS, WITH THE DESCRIPTION OF A NEW SPECIES OF (, GNATHOPHYLLIDAE)

BY

RICHARD H. TITGEN Hawaii Institute of Marine Biology, P.O. Box 1346, Coconut Island, Kaneohe, Hawaii 96744-1346, U.S.A.

RÉSUMÉ

Cinq espèces de crevettes de la famille des Gnathophyllidae sont connues de l'archipel hawaiien. L'une, Gnathophyllumprecipuum sp. nov., nouvelle pour la science, se distingue des autres espèces du genre par le dessin des marques colorées et par le rostre inhabituel. La clef sera utile pour la séparation des espèces de crevettes gnathophyllides connues de l'archipel hawaiien.

The small caridean family Gnathophyllidae, which is closely related or syn- onymous to the palaemonid subfamily Pontoniinae (A. J. Bruce, 1986), is rep- resented in the Hawaiian Islands by five species in four genera. Two species, Gnathophylloides mineri Schmitt, 1933, and Gnathophyllum americanum Gu6rin Meneville, 1856, are circumtropical in distribution, and a third species, Hymenocera picta Dana, 1852, is widely distributed throughout the tropical Pacific. Of the remaining two species, Leaicaris mammillata (Edmondson, 1931 ) is known from the Hawaiian Islands, Ogasawara Islands and Ryukyu Islands (Fujino & Takeda, 1977), and a new species, described herein, is known only from the Hawaiian Islands. Gnathophyllid shrimp are commonly associated with . Gnathophylloides mineri and L. mammillata are obligate commensals of echinoids, and H. picta is a predator on a variety of asteroids, including the crown-of- thorns Acanthaster Planci (Linnaeus, 1758). No such obligate or well established association is known for the genus Gnathophyllum Latreille, 1819. However, in Florida Manning (1963) occasionally found G. americanum among the spines of the echinoid Lytechinus variegatus (Leske, 1778), and Bruce (1975) reported this species as browsing on asteroid papulae. The restricted synonymies listed consist primarily of Hawaiian references. The initials "BPBM" refer to the Bernice P. Bishop Museum, and "cl." is a measurement of carapace length including the rostrum. 201

Gnathophylloides mineri Schmitt, 1933 Gnathophylloidesmineri Schmitt, 1933: 7, fig. 3. - Castro, 1971: 398. Material examined. - 1 specimen, BPBM Acc. No. 1977.30, Oahu, collected from an echinoid, Pseudoboletiaindiana, coll. A. Fielding, 29 January 1977.

Remarks. - Gnathophylloides mineri is a circumtropical obligate commensal of echinoids. In Hawaii, it is associated with Pseudoboletia indiana (Michelin, 1862) and Tripneustes gratilla (Linnaeus, 1758). Castro (1971) described the color pattern of Hawaiian specimens of G. mineri, stating that the dorsal surface of the body is pink with thin, dark longitudinal lines. There is a broad, white longitudinal stripe on each side of the carapace and abdomen; the inferior border of the stripe is white or purple depending on the color of its echinoid host. Both Hawaiian hosts of Gnathophylloides mineri occur throughout the Hawaiian Archipelago from Hawaii to Midway. Although the shrimp is cur- rently reported only from Oahu, the distribution of the hosts suggest that it may be distributed throughout the Hawaiian Archipelago.

Hymenocera picta Dana, 1852 - HymenocerapictaDana, 1852: 593; 1855: pl. 39 fig. 3a-c. - Tinker, 1965: 32, pi. 4. Debelius, 1984: 54, figs. on pp. 52, 53. Hymenocerasp. - Mortensen, 1917: 76-77, fig. 14 (from Hilo, Hawaii). Hymenocera elegans.- Edmondson, 1935: 17. - Hiatt, 1948: 79. - Barry, unpublished: 19. Material examined. - 1 specimen, BPBM S3895, Oahu, Kaneohe Bay, coll. C. H. Edmond- son, 23 August 1934, shoal water, in Porites. - 1 specimen, BPBM S8285, Oahu, Ala Moana reef near entrance to Ala Wai Harbor, coll. T. M. Gosliner, 29 April 1973, depth 1.5 m. - 1 specimen, BPBM S8286, Oahu, off Lahilahi Pt., coll. J. E. Randall, 11July 1970, depth 27.4 m, in cave with Stenopusjuvenile.

Remarks. - Hymenocera picta usually occurs in pairs and is a predator on various asteroids. This strikingly attractive shrimp is immediately recognizable by the leaf-like expansions on the second pereiopods and its distinctive color pattern. The background color is light pink, and there are several large red-to- purple spots with yellow margins on the carapace and abdomen. Originally described from the Tuamotu Archipelago, further investigation is necessary to determine if H. picta is synonymous with the Indian Ocean species H. elegans Heller, 1861. At present, these two species can only be separated on the basis of color (Debelius, 1984), H. elegans having browner tones rather than the red of H. picta. It will also have to be determined which species of Hymenocera occurs in the eastern Pacific (A. J , Bruce, personal com- munication 1986; and Mortensen, 1917: 77, fig. 13, who reported it from Taboga Island, Gulf of Panama). Hymenocera picta is widely distributed throughout the Pacific Ocean. The Bishop Museum has Hawaiian specimens from the islands of Oahu and