//6y 23 March 1999 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 112(]):94-96. 1999. A new species of Siamosquilla from Indonesia (Crustacea: Stomatopoda: Protosquillidae) Mark V. Erdmann and Raymond B. Manning (MVE) Department of Integrative Biology, University of California at Berkeley, Berkeley, California 94720, U.S.A.; (RBM) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC. 20560-0163, U.S.A. Abstract.?Siamosquilla sexava, the second species of the genus, is de- scribed from Indonesia. It can be distinguished from the type species, S. hyl- lebergi Naiyanetr, from Thailand, by the shorter median rostral spine, the larger ocular scales, the much broader telson, and differences in ornamentation of the fused sixth abdominal somite and telson. Among the stomatopods collected by one of us (M. V. E.) during a six-year field study in Indonesia was a minute protosquillid which proved to be the second known spe- cies of Siamosquilla Naiyanetr, 1989. It is described below. Abbreviations used in the account in- clude: LON, Lembaga Oseanologi Nasional (National Institute of Oceanoraphy), Jakar- ta, Indonesia; TL, total length, measured on the midline; USNM, National Museum of Natural History, Smithsonian Institution, Washington, DC, U.S.A. The holotype and some paratypes have been deposited in the USNM; two paraty- pes are in the LON. Family Protosquillidae Manning, 1980 Siamosquilla Naiyanetr, 1989 Siamosquilla sexava, new species Fig. 1 Material examined.?Indonesia: Moro- maho, Tukang Besi: 12, TL 18 mm (ho- lotype, USNM 260927), 25 5, TL 16-17 mm (paratypes, LON).?Gili Meno, Lom- bok: irj, TL 17 mm, 15, TL 18 mm (par- atypes, USNM 260928).?Melanguane, Sangihe-Talaud: 15, TL 17 mm (paratype, USNM 260929).?Taupun, Togian Islands: 16% TL 13 mm (paratype, USNM 260930). Diagnosis.?Size very small, TL less than 20 mm in adults. Cornea broadened, set obliquely on stalk. Ocular scales well developed, produced into triangular lobes laterally, extending nearly to lateral rostral spine in adults. Rostral plate sharply trispinous, median spine distinctly upturned distally, extending to base of corneas; ventral projection of ros- tral plate large, obtusely rounded ventrally. Lateral rostral spines extremely long, slen- der and recurved, length nearly two-thirds that of median spine. Basal part of rostral plate very thin. Anterior margins of lateral plates of carapace concave, anterolateral an- gles strongly produced to a sharp point, ex- tending anteriorly to base of rostral plate. Mandibular palp absent. Five epipods present. Raptorial claw with inflated part of outer margin of dactylus notched. Propodus with single movable spine proximally on inner margin. Anterior 4 abdominal somites smooth, unarmed, not carinate dorsally. Fifth ab- dominal somite smooth medially, with sin- gle low longitudinal carina laterally above lateral margin, separated from margin by a groove, armed with posterolateral spine. Sixth abdominal somite entirely fused with teJson in adults, dorsal surface rough, with shallow, irregularly curved grooves, lacking carinae entirely. 1 VOLUME 112, NUMBER I 95 Fig. I. SiamosquUla sexavu, new species, female holotype, TL 18 mm. a. Anterior part of body, dorsal view (apex of left ocular scale damaged); b. Rostral plate, lateral view; c, Fused sixth abdominal somite and telson and left uropod, dorsal view. Scales = I mm. Telson much wider than long, dorsal sur- face rough, slightly inflated, with 3 very in- distinct bosses. Median boss outlined by a shallow groove in dorsal surface of telson; boss rounded anteriorly, converging poste- riorly; outline of submedian bosses even less distinct, extending posteriorly almost to posterior margin of telson. Median fissure completely fused, no longer visible. Three pairs of marginal teeth, submedians with moveable apices arising submarginally un- der submedian marginal projections. Inter- mediate teeth very low and rounded, almost indistinguishable in larger specimens. Lat- eral teeth more distinctly produced, with rounded apices. Separation between three pairs of marginal telson teeth shallow and rounded. Submedian teeth with 12-14 den- ticles on either side of midline, increasing noticeably in length laterally, intermediate teeth each with 2 fixed mesial denticles, lat- erals each with 1 denticle. Lateral margins of telson straight, rounded distally. Uropods stout, proximal segment of ex- opod with 9 short movable spines laterally, distalmost extending beyond midlength of distal segment, with fixed distal spine ven- trally. Inner margin of uropodal exopod se- tose; uropodal endopod with normal com- plement of setae. Inner spine of basal pro- longation of uropod much shorter than out- er. Size.?Males (n = 2), TL 13-17 mm. Fe- males (n = 5), TL 13?18 mm. Remarks.?This small species has a very distinctive rostral plate, with long, recurved lateral spines, and a telson that is most re- markable for its lack of distinguishing fea- tures; the sixth abdominal somite is fused to the telson, which has almost indiscern- ible bosses and a fused median fissure. 57a- mosquilla sexava differs from S. hyllebergi in numerous features: the median rostral spine is shorter, extending to, rather than beyond, the cornea and the lateral rostral spines are longer; the ocular scales are broader; in adults the anterolateral angles of the carapace are sharper and more pro- 96 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON nounced; the dorsal sculpture of the fused sixth abdominal somite and telson is much more elaborate; and the telson is much broader. The fixed projections on the posterior margin of the telson are much more pro- nounced in S. hyllebergi than in S. sexava, and the submedian projections in the former species probably obscure the submarginal, movable submedian teeth of the telson, which are clearly visible in S. sexava. In S. sexava, the size of the ocular scales increases allometrically, and in very small specimens of 5. sexava the scales resemble those of larger S. hyllebergii; they increase in width with increasing TL. Distribution.?Known only from eastern Indonesia, where it is relatively widespread. Recorded from five regions: Lombok, San- gihe-Talaud, Togian Islands, and Tukang Besi Archipelago. Etymology.?The species name is from the word sexava, which means "mantis" in Bahasa Talaud, the local language in one of the collection localities (Melanguane, San- gihe-Talaud). The local fishermen, school teachers and children there were most help- ful in assisting with collecting, and were fully cognizant of the differences between stomatopods and other decapod shrimp, comparing stomatopods to the "sexava" without any solicitation. Their assistance is most appreciated. Acknowledgements We thank the Indonesian Institute of Sci- ences for sponsoring Erdmann's project, and Kalam Sebayang and Ibu Dewi Soen- arijadi for their assistance with research vi- sas. Dr. Mohammad Kasim Moosa was the Indonesian sponsor of this research, and Erdmann gratefully acknowledges his men- torship on stomatopod morphology and his continual support of this project. We also thank Dr. Sukarno, Dr. Suharsono, and Dr. Anugerah Nontji of the Indonesian Institute of Sciences. Funding for Erdmann's research was pro- vided by grants from the UC Pacific Rim Research Program, the NSF International DDIG (#9503060 and #9704616) Program and a visiting scientist appointment from the Smithsonian Institution. Lilly King Manning prepared the figure. This is con- tribution no. 467 from the Smithsonian Ma- rine Station at Fort Pierce, Florida; the sup- port of that program for Manning's studies of stomatopod systematics is gratefully ac- knowledged. We gratefully acknowledge the reviews of Shane Ahyong, David K. Camp, and Roy K. Kropp as well as the cooperation of Rafael Lemaitre. Literature Cited Naiyaneir, P. 1989. SicDno.squilla hyllebergi. a new ge- nus and new species of stomatopod from Thai- land. In E. A. Ferrero, ed.. Biology of stomato- pods. Selected symposia and monographs, U.Z.I., 3:281-284. Muchi, Modena.