Picnogonidos

SPIXIANA

32

1

9–34

München, August 2009

ISSN 0341–8391

Morphology of shallow-water sea spiders from the Colombian Caribbean
(Arthropoda: Pycnogonida)

Maria Fernanda Montoya Bravo, Hans-Georg Müller, Claudia P. Arango, Paulo Tigreros & Roland R. Melzer

Montoya Bravo, M. F., Müller, H.-G., Arango, C. P., Tigreros, P. & Melzer, R. R. (2009): Morphology of shallow-water seaspiders (Arthropoda: Pycnogonida) from the Colombian Caribbean. – Spixiana 32/1: 9-34 Scanning EM redescriptions of nine pycnogonid species belonging to the families Ammotheidae, Phoxichilidiidae, and Callipallenidae are provided and referenced to earlier light microscopical descriptions of the respective species. Specimens were collected at various locations and different infralittoral habitatsaround Santa Marta along the Caribbean coast of Colombia. Maria Montoya, Hans-Georg Müller and Roland Melzer (corresponding author), Zoologische Staatssammlung, Münchhausenstr. 21, 81247 München, Germany; e-mail: melzer@zsm.mwn.de Claudia Arango, Biodiversity Program, Queensland Museum, P.O. Box 3300, South Brisbane 4101 Queensland, Australia Paulo Tigreros, Universidad Jorge Tadeo Lozano, Carrera 2#11-68 Santa Marta, Colombia.

Introduction Most Pycnogonida or sea spiders of the tropical, coastal seas are very small (1-2 mm body length) and have cryptic habitats in the phytal zone or close to coelenterates, sponges and other benthic organisms (Arnaud & Bamber 1987). In the present paper we examine nine species of pycnogonids found at different infralittoral habitats in the area of Sta.Marta at the Caribbean coast of Colombia. The last comprehensive study on the pycnogonids of this area is by Müller (1990) with the description of 50 species, including seven new to science (see also Müller & Krapp (in press)). Since then only a few studies dealt with the Colombian pycnogonids, including reports about three species new for this area (Nymphon surinamense Stock, 1975, Anoplodactylusinsignis Hoek, 1881, Pallenopsis schmitti Hedgpeth, 1943) by Arango

(2000). The material for these studies was collected at Tayrona national park and around Cartagena. In the present study we contribute to the knowledge of some species of sea spiders from the Santa Marta region, mainly from unprotected coasts that are intensely used for fishing and tourism. For documentation we used thescanning electron microscope (SEM) that allows a direct and detailed analysis of the species-specific morphological characters, and we provide SEM (re)descriptions of the species. The present study aims to contribute to a pictorial atlas of Colombian pycnogonids. The classical studies on Caribbean pycnogonids that we refer to are by Marcus (1940), Hedgpeth (1948), Stock (1975, 1986) and Child (1979). Forsynonymy and detailed taxonomy see Müller (1990, 1993a), Müller & Krapp (in press).

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Animals and Methods
Sampling and fixation. The pycnogonids for the present study were collected at various locations between the airport bay of Santa Marta, west of the city, and the Cabo Arrecifes, about 30 km east of the city in the Tayrona national park. A detailed description of the sampling sitesincluding the Bavarian State Collection’s storage number is given below for each of the studied specimens. In order to find pycnogonids from different habitats, samples were taken around corals and other coelenterates, from coral rubble, under stones and by whirling up sediment. Of these techniques, the under stone method, i.e. taking stones out of the water and checking the under stone benthiccommunities for pycnogonids proved to be the most successful way. The collected animals were fixed in 3 % formaldehydeborax in sea water and the next day transferred to 70 % ethanol. Cleaning of specimens. In order to get Scanning EM pictures of sufficient quality as well as for light microscopy most specimens had to be cleaned. For that, different methods were used: KOH solution in combination with...