UNIVERSITY OF AMSTERDAM. Abstract. ment. The subject of the paper is. appropriate as it was prof. Stock, who collected

Transcription

1 Chace, Beaufortia INSTITUTE OF TAXONOMIC ZOOLOGY (ZOOLOGICAL MUSEUM) UNIVERSITY OF AMSTERDAM Vol. 4, no. 5 October 22, 990 Notes on Salmoneus Arubae (Schmitt, 936) (Crustacea, Decapoda, Caridea) L.B. Holthuis Rijksmuseum van Natuurlijke Historie, P.O. Box 957, 2300 RA Leiden, the Netherlands Abstract A redescription is given of Salmoneus arubae (Schmitt, 936), based on new material collected at the Island of Curaçao, the Netherlands Antilles. Investigations on the interstitial fauna of the ment. subject of the paper is especially Netherlands Antilles carried out in 984 by Prof. Dr. J. H. Stock of Amsterdam University, of group collaborators, produced and his also interesting material of species that cannot be classed as true members of the interstitial fauna. One of such species is Salmoneus arubae, an described in 936 after Alpheid shrimp, a single incomplete specimen; no new finds of appropriate as it was prof. Stock, who collected the material and immediately recognized it as something of interest. special drawings illustrating this article are made by Mr. C. H. J. M. Fransen, curator of Crustacea of the Rijksmuseum van Natuurlijke Historie, to whom I express here my deep gratitude for helping me in this respect. this species have been reported after the original description. At four occasions prof. Stock collected this Salmoneus using a BouRouch pump in the marine interstitial of the S.W. coast of Salmoneus arubae (Schmitt, 936) Jousseaumea arubae Schmitt, 936: , pl. Curaçao; he obtained 5 in all. This specimens new material now makes it possible to complete 2 figs. ag. Salmoneus arubae 972: 79. the original description (the larger first leg was missing in the holotype) and to some information on the variability of some of the charac give ters of the species. It is a pleasure to dedicate this to paper Prof. Dr. J. H. Stock Jzn at the occasion of his retire Material. J. F. Kennedy Boulevard, 500 m E. of Concorde Hotel, Willemstad, S.W. coast of Curaçao, Netherlands Antilles, 2 07'3"N 68 57'50"W; collected with BouRouch biophreatic pump at m seaward of highwater line, at a sediment depth of 0.5 m; sediment Amsterdam Expeditions to the West Indian Islands no. 68 coarse sand, salinity 40% o; 29 May 984; J. H. 09

2 Fig.. Salmoneus arubae (Schmitt, 936), specimen from Sta ac, large first pereiopod. a, inside view; b, outside view; c, chela; d, third pereiopod, inside; e, fifth pereiopod. a, b, x 24; ce, x 60.

3 2 Stock, no specimen, cl. 4.5 mm, ti. carapace between the two longitudinal ridges is mm. provided with small irregular rounded and 2. ' Same locality and collecting gear; taken at 3 m seaward of highwater line at a sediment elongate depressions, that give the surface a somewhat rough and eroded appearance. depth of 0.75 m; sediment coarse sand and posterior branchial region of the carapace coral grit, salinity 40% o; 30 May 984; J. H. sometimes shows an oblique not very distinct Stock, no specimen, cl. 5 mm, tl. ridge in the larger specimens, while an indica 3 mm. tion of a median cervical depression may be 3. Same locality and collecting gear; taken at noted. As some of the specimens are slightly 3.5 m seaward of highwater line at a sediment shrivelled by the action of the preservative, it is depth of 0.75 m; sediment coarse, mostly sand difficult to be certain which features are natural and coral rubble; June 984; J. H. Stock, no. and which are caused artificially. Below the specimens, cl..3 and.8 mm. longitudinal ridges, the lateral surface of the 4. Blauw Baai, S.W. coast of Curaçao, carapace is pitted as is also the dorsal surface of slightly the abdominal somites. telson agrees well N.W. of Piscadera Baai and Willemstad, 2 08 ' 2"N ' 57 "W; eastern part of with the figure provided by Schmitt (936). beach, collected with BouRouch pump in the stylocerite usually reaches to or almost to surf zone; sediment of very fine pebbles; 23 the end of the second segment of the antennular May 984; J. H. Stock, no specimen, cl..5 mm. peduncle, it hardly ever reaches beyond. inner branch of the upper antennular flagellum is very short and its free portion consists of DESCRIPTION about 5 or 6 segments. scaphocerite is about 0.5 to 0.6 times as rostrum is rather variable in shape. In wide as long. outer tooth is distinct, it some specimens it reaches almost to the end of sometimes attains the end of the lamella, but the third segment of the antennular peduncle, usually falls short of it. in most it does not advance beyond the second segment. It usually is the end of wider and larger first pereiopod, which lacks in the holotype, is well developed and differs greatly blunter than that of Salmoneus evermanni from the shorter leg in size and shape. It is pres (Rankin, 898), but in some specimens the tip ent in both larger specimens. fingers are narrows more strongly than shown in Schmitt' s about as long as the palm, they are slender and figure. lateral teeth are short and wide in all in specimens, some they are more conspicuous than in others, but they are never so narrow as in S. evermanni. All specimens show a short median longitudinal ridge dorsally on the are laterally compressed, straight with only the tips strongly curved; the two tips are crossing. cutting edges bear about 5 distinct teeth, the of which proximal are the smallest and placed close together; the teeth are placed over tip of the rostrum; this ridge usually does not the full length of the cutting edge, only the extend posteriorly behind the level of the lateral extreme distal part being unarmed. Just outside teeth,and, as also indicated by Schmitt (936), this unarmed portion there is a small rounded is only visible when the upper surface of the knoblike tubercle. teeth on the cutting rostrum is superficially dried. In the young the specimens, surface of the carapace is smooth and In all shiny, usually slightly pitted. specimens there is a low and blunt longitudinal ridge, or actually an elongated elevated area, in the anterior half of each lateral surface of the carapace, with a above it. In parallel the groove edge are triangular and sharply pointed. palm is swollen, being distinctly wider and higher than the fingers combined. lower margin of the with that palm merges of the fixed finger under a sigmoid curve. palm is oval in transverse section and shows no ridges, teeth or twists, its surface is smooth. carpus is larger specimens the median surface of the half as long as the palm; it is short and cup

4 Fig. 2. Salmoneus arubae (Schmitt, 936), fingers of large first cheliped. x 20. shaped, being slightly constricted near the small spines and a larger one distally. anterior margin and distinctly narrowed in the carpus is about as long as the and has propodus basal part. anterior margin shows a blunt a small distoventral spinule. merus is inner lobe. merus is longer than the palm almost as long as the propodus and dactylus and about four times as long as wide. It shows together, it is wider than the distal three no teeth or spines. lower surface is flat segments. ischium is about as long as the tened or somewhat concave. ischium is merus and bears a movable spine in the basal about 3/4 as long as the merus and likewise part. unarmedbut for a movable spinule in the basal fifth leg has the dactylus less than 2/5 as part of the outer surface. smallest of the examined specimens has both first legs; these long as the propodus. distal part of the pro are slightly different in size, and their shape is rather similar. This evidently is due to the fact that the animal is not yet full grown. second leg is well described and figured by Schmitt (936). third leg is slightly more slender than the one figured by Schmitt. In all specimens in which this leg is still present, the dactylus is slightly less than half as long as the propodus, being usually slightly longer and more slender than shown in Schmitt' s figure. character of the short dactylus distinguishes this species immediately from S. evermanni in which the dactylus is more than half (5/7 according to Christoffersen, 982: 94) as long as the propodus. posterior margin of the propodus carries 4 Fig. 3. Locality off J. F. Kennedy Boulevard, Willemstad, where Salmoneus arubae (Schmitt) was collected. Bou Rouch in the pump photograph is at 4 m seawards of the highwater line. Photograph J. H. Stock,

5 Schmitt's So podus carries several transverse rows of hairs and some spinules in the posterior part. carpus is somewhat shorter than the propodus and almost as long as the merus. ischium is less than half as long as the merus unarmed. and is Oligochaeta (27, 33, 39), Sipunculida (27), Nematoda (39), Mollusca (Caecum) (27, 33), Ostracoda Pycnogonida (39), (39), and Copepoda (Harpacticoida Cyclopoida) (33, 39), Amphipoda (Hadziidae, 27, 33, 39; Bogidiella, 39; Psammogammarus, 39), largest specimen most likely is a female, Tanaidacea(33), Isopoda (Curassanthura, 27), judging by the wide pleura, which form, what may have been a brood pouch. It, like the other rmosbaenacea (Halosbaena 977; 27, 33, 39). acanthura Stock, large specimen, has a distinct appendix Distribution. far the present species masculina on the second pleopod; a feature also has only been reported from two islands of the found in the females of all other species of NetherlandsAntilles: Curaçao and Aruba, both Salmoneus checked thusfar this on point (Carvacho, 989: ). Size. holotype has a total length of 3 mm. largest two specimens of the lying off the north coast of Venezuela. holotype was collected at Punta Braboe on the S.W. coast of Aruba, slightly N.W. of Oranjestad, at 2 32'N 70 04'W (8 July 930, present materialhave a total length of 3 and leg. P. Wagenaar Hummelinck). present mm (cl. 5 and 4.5 mm). carapace lengths material originates from two localities on the of the smaller specimens mm. varies from.3 to.8 S.W. coast of Curaçao: J. F. Kennedy Boulevard, Willemstad, and Blauw Baai, Colour. colour of a living specimen slightly N.W. of Willemstad. (no. 8433) was described by prof. Stock (in litt., 4 August 986) as follows: "Carapace dorsally orangebrown, eye black, rest of the body unpigmented". Habitat. holotype was collected by Dr. P. Wagenaar Hummelinck from "between corals from a "Schorrenfläche", about foot deep"; the indicated is that depth of the water. LITERATURE Bou, C. & R. ROUCH, 967. Un nouveau champ de recherches sur la faune aquatique souterraine. Comptes Académie des Sciences, Rendus hebdomadaires Paris, (D) 265 (4): CARVACHO, A., 989. Sur l'appendix masculina chez Salmoneus (Decapoda, Alpheidae). Crustaceana, 57 All the present specimens were collected with a (3): CHACE, F. A., 972. of the Smithsonianshrimps Bredin Caribbean Expeditions with a summary of species (Crustacea: the West Indian shallowwater Decapoda: Natantia). Smithsonian Contributions to Zoology, 98: ix, 79. CHRISTOFFERSEN, M. L., 982. Distribution of warm water alpheoid shrimp (Crustacea, Caridea) on the continental shelf of eastern South America between 23 and 35 lat.s. Boletim Instituto oceanógrafico Sào Paulo, 3: 932. SCHMITT, W. L., 936. Macruran and anomuran BouRouch biophreatic pump in the marine interstitial; a description of this is pump given by Bou & Rouch (967: ). pump was driven into the substrate at fixed distances (50 cm apart) seaward of the highwater line; it was pushed into the sediment to up depths of 50 to 75 centimeters, from which the depths interstitial water was into a net which pumped caught the In all instances the sedi organisms. ment was quite coarse, consisting of coarse Crustacea from Bonaire, Curaçao and Aruba. sand, coral grit, coral rubble and fine pebbles. All stations were truly marine, the salinity being about 40% 0 Of some of the stations the Zoologische Ergebnisse einer Reise nach Bonaire, Curaçao und Aruba im Jahre 930. No. 6. Zoologische Jahrbücher, (Syst.) 67: , pis. more conspicuous accompanying fauna was noted, as follows: Polychaeta (sta. 27, 39), Received: November 7, 989 Institute of Taxonomic Zoology (Zoologisch Museum), University of Amsterdam, P.O. Box 4766, 009 AT Amsterdam, the Netherlands 3