ZOOTAXA

1262

Taxonomy and biogeography of the freshwater of , (Brachyura: : , Platythelphusidae, Deckeniidae)

SADIE K. REED & NEIL CUMBERLIDGE

Magnolia Press Auckland, New Zealand SADIE K. REED & NEIL CUMBERLIDGE and biogeography of the freshwater crabs of Tanzania, East Africa (Brachyura: Potamoidea: Potamonautidae, Platythelphusidae, Deckeniidae) (Zootaxa 1262) 139 pp.; 30 cm. 17 July 2006 ISBN 1-877407-81-X (paperback) ISBN 1-877407-82-8 (Online edition)

FIRST PUBLISHED IN 2006 BY Magnolia Press P.O. Box 41383 Auckland 1030 New Zealand e-mail: [email protected] http://www.mapress.com/zootaxa/

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ISSN 1175-5326 (Print edition) ISSN 1175-5334 (Online edition) Zootaxa 1262: 1–139 (2006) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA 1262 Copyright © 2006 Magnolia Press ISSN 1175-5334 (online edition)

Taxonomy and biogeography of the freshwater crabs of Tanzania, East Africa (Brachyura: Potamoidea: Potamonautidae, Platythelphusidae, Deckeniidae)

SADIE K. REED1 & NEIL CUMBERLIDGE2 1 Department of Biology, 185 ASEC-W, University of Akron, Akron, OH 44325-3908, USA

2 Department of Biology, Northern Michigan University, Marquette, Michigan 49855-5301, USA.

TABLE OF CONTENTS

Abstract ...... 4 Introduction ...... 5 Materials and methods ...... 8 Taxonomy ...... 11 List of found in Tanzania ...... 11 Key to families and genera of freshwater crabs of Tanzania ...... 12 Family Potamonautidae Bott, 1970...... 12 MacLeay, 1838 ...... 12 Diagnosis ...... 12 Remarks ...... 12 Distribution ...... 13 Key to species of Potamonautes from Tanzania ...... 15 1. Potamonautes emini (Hilgendorf, 1892) ...... 15 2. Potamonautes gerdalensis Bott, 1955 ...... 18 3. Potamonautes infravallatus (Hilgendorf, 1898) ...... 19 4. Potamonautes johnstoni (Miers, 1885) ...... 21 5. Potamonautes lirrangensis (Rathbun, 1904) ...... 23 6. Potamonautes loveridgei (Rathbun, 1933) ...... 25 7. Potamonautes obesus (A. Milne-Edwards, 1868) ...... 27 8. Potamonautes pilosus (Hilgendorf, 1898) ...... 28 9. Potamonautes platycentron (Hilgendorf, 1897) ...... 30 10. Potamonautes platynotus (Cunnington, 1907) ...... 31 11. Potamonautes raybouldi Cumberlidge & Vannini, 2004 ...... 33 12. Potamonautes suprasulcatus (Hilgendorf, 1898) ...... 34 13. Potamonautes unisulcatus (Rathbun, 1933)...... 37

Accepted by P. Castro: 3 Mar. 2006; published: 17 Jul. 2006 3 ZOOTAXA 14. Potamonautes xiphoidus n. sp...... 38 1262 Family Deckeniidae Hilgendorf, 1869 ...... 40 Diagnosis ...... 40 Distribution ...... 40 Remarks ...... 40 Natural history ...... 41 Genus Hilgendorf, 1869 ...... 41 Key to the species of Deckenia ...... 41 15. Deckenia imitatrix Hilgendorf, 1869 ...... 42 16. Deckenia mitis Hilgendorf, 1898 ...... 43 Family Platythelphusidae Colosi, 1920 ...... 44 Diagnosis ...... 45 Distribution ...... 45 Remarks ...... 45 Natural history ...... 45 Genus A. Milne-Edwards, 1887 ...... 45 Key to the species of Platythelphusa ...... 46 17. Platythelphusa armata (A. Milne-Edwards, 1887) ...... 47 18. Platythelphusa conculcata Cunnington, 1907 ...... 48 19. Platythelphusa denticulata Capart, 1952 ...... 49 20. Platythelphusa echinata Capart, 1952 ...... 50 21. Platythelphusa immaculata Marijnissen, Schram, Cumberlidge & Michel, 2004 . . 51 22. Platythelphusa maculata (Cunnington, 1899) ...... 52 23. Platythelphusa polita Capart, 1952 ...... 53 24. Platythelphusa praelongata Marijnissen, Schram, Cumberlidge & Michel, 2004 . . 54 25. Platythelphusa tuberculata Capart, 1952 ...... 55 Discussion ...... 56 Freshwater distribution patterns...... 58 Acknowledgements ...... 61 References ...... 61 Appendix ...... 133

ABSTRACT

The taxonomy of the freshwater crabs of Tanzania, East Africa is revised based on a large collection of previously unreported material. The crabs are treated here as a distinct regional subset of the African continental fauna. We recognize 25 species belonging to three genera (Potamonautes MacLeay, 1838, Platythelphusa A. Milne-Edwards, 1872, and Deckenia Hilgendorf, 1869a) and three families (the Potamonautidae Bott, 1970, the Platythelphusidae Colosi, 1920, and the Decken- iidae Ortmann, 1897). Tanzania is home to fourteen species of Potamonautes (including one new species), 9 species of Platythelphusa and 2 species of Deckenia. These estimates can be expected to change as the taxonomy of the freshwater crabs of this region becomes more refined. Potamonautes unisulcatus (Rathbun, 1933) is removed from synonymy and is recognized as a valid species; P. platycentron (Hilgendorf, 1897), originally a subspecies of P. johnstoni (Miers, 1885), is regarded

4 © 2006 Magnolia Press REED & CUMBERLIDGE as a valid species; P. ambiguus (Rathbun, 1904) is treated here as a junior subjective synonym of P. ZOOTAXA johnstoni (Miers, 1885), and P. johnstoni stappersi (Balss, 1936) is treated as a junior subjective 1262 synonym of P. loveridgei (Rathbun, 1933). The present work adds another species of Potamo- nautes, P. xiphoidus n. sp. from Tanzania. A number of morphological characters (including the shape and size of the dorsal membrane of gonopod 1) are identified to help clarify the taxonomy of Potamonautes in Tanzania. A revised species list for Tanzania is provided, as well as updated iden- tification keys to the families, genera and species of Tanzanian freshwater crabs. The distribution of each species is refined based on new localities. Three out of 25 species (12.5%) (P. infravallatus, P. unisulcatus and P. xiphoidus) are endemic to Tanzania, but this number rises to 13 out of 25 (52%) if the endemic species which occur in other countries that border the lake are included. Only two of the 25 Tanzanian species of freshwater crabs (P. lirrangensis and P. suprasul- catus) occur outside of the East African region in the D. R. Congo and Malawi.

Key words: Crustacea, Brachyura, Potamoidea, Potamonautidae, Potamonautes, Platythel- phusidae, Platythelphusa, Deckeniidae, Deckenia, freshwater crabs, taxonomy, Tanzania, Lake Tanganyika, East Africa

INTRODUCTION

The fauna of Africa as a whole comprises over 100 species that are cur- rently assigned to 11 genera and four families (Cumberlidge 1999). The fauna of Tanzania is treated here as a distinct regional subset of the African continental fauna and recognizes 25 species in three genera and three families (Bott 1955; Williams 1968; Cumberlidge 1999). These estimates can be expected to change as exploration increases and the taxon- omy of the freshwater crabs of this region becomes more refined. Freshwater crabs are of great economic importance in Africa because these sometimes form a significant part of the diet of large numbers of people in rural areas, and because the crabs have been implicated in the transmission of disease-causing parasites in humans (Williams et al. 1964; Williams 1968; Voelker & Sachs 1977). Furthermore, the recent upsurge of interest in biodiversity inventories and conservation in Africa (an inter- est that is particularly strong in East Africa), has led to an increased need for biologists and conservation agencies to be able to identify the freshwater crabs of this region. The general neglect of African freshwater crabs over the years means that today their taxonomy is unstable and unreliable, species lists are inaccurate, distribution patterns are largely unknown, and little is known of the population levels or conservation status of most spe- cies in the region. Inadequate keys also make identification difficult for non-specialists. Three genera (Potamonautes MacLeay, 1838, Platythelphusa A. Milne-Edwards, 1872, and Deckenia Hilgendorf, 1869) belonging to three families (Potamonautidae Bott, 1970, Platythelphusidae Colosi, 1920, and Deckeniidae Ortmann, 1897), have so far been recorded from Tanzania. Two of these genera have been the subject of recent taxonomic revisions: Deckenia by Ng et al. (1995) and Platythelphusa by Cumberlidge et al. (1999), with additions by Marijnissen et al. (2004). Less attention has been paid to the taxonomy

FRESHWATER CRABS OF TANZANIA © 2006 Magnolia Press 5