PLATINUM The Journal of Threatened Taxa (JoTT) is dedicated to building evidence for conservaton globally by publishing peer-reviewed artcles online OPEN ACCESS every month at a reasonably rapid rate at www.threatenedtaxa.org. All artcles published in JoTT are registered under Creatve Commons Atributon 4.0 Internatonal License unless otherwise mentoned. JoTT allows allows unrestricted use, reproducton, and distributon of artcles in any medium by providing adequate credit to the author(s) and the source of publicaton. Journal of Threatened Taxa Building evidence for conservaton globally www.threatenedtaxa.org ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) Note A new distribution record of the Pentagonal Sea Urchin Crab Echinoecus pentagonus (A. Milne-Edwards, 1879) (Decapoda: Brachyura: Pilumnidae) from the Andaman Islands, India Balakrishna Meher & Ganesh Thiruchitrambalam 26 October 2019 | Vol. 11 | No. 13 | Pages: 14773–14776 DOI: 10.11609/jot.4909.11.13.14773-14776 For Focus, Scope, Aims, Policies, and Guidelines visit htps://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-0 For Artcle Submission Guidelines, visit htps://threatenedtaxa.org/index.php/JoTT/about/submissions#onlineSubmissions For Policies against Scientfc Misconduct, visit htps://threatenedtaxa.org/index.php/JoTT/about/editorialPolicies#custom-2 For reprints, contact <[email protected]> The opinions expressed by the authors do not refect the views of the Journal of Threatened Taxa, Wildlife Informaton Liaison Development Society, Zoo Outreach Organizaton, or any of the partners. The journal, the publisher, the host, and the part- Publisher & Host ners are not responsible for the accuracy of the politcal boundaries shown in the maps by the authors. Partner Member Threatened Taxa Journal of Threatened Taxa | www.threatenedtaxa.org | 26 October 2019 | 11(13): 14773–14776 Note A new distribution record of the to the Hawaiian Islands (Chia et al. Pentagonal Sea Urchin Crab Echinoecus 1999). Males and pre-adult females pentagonus (A. Milne-Edwards, 1879) of E. pentagonus mostly live on (Decapoda: Brachyura: Pilumnidae) from the surface of sea urchins but ISSN 0974-7907 (Online) ISSN 0974-7893 (Print) the Andaman Islands, India sometmes they can be found near the rectum while adult females are PLATINUM Balakrishna Meher1 & Ganesh Thiruchitrambalam2 restricted to the rectum in a calcifed OPEN ACCESS gall-like structure (Castro 1971, 1,2 Department of Ocean Studies & Marine Biology, Pondicherry 2015). For the frst tme in India a University, Brookshabad Campus, Port Blair, Andaman & Nicobar berried female E. pentagonus was Islands 744112, India. 1 [email protected], 2 [email protected] collected from the rectum of the sea urchin Echinothrix (corresponding author) diadema (Linnaeus) from Malacca Beach, Car Nicobar in 1959 by Tiwari (see Sastry 1981). Later Prakash et al. (2012) reported a male E. pentagonus clinging on the For the frst tme, the Pentagonal Sea Urchin Crab ventral side of the sea urchin host Echinothrix calamaris Echinoecus pentagonus (A. Milne-Edwards, 1879) from Agat Island, Lakshadweep. is recorded from the rocky intertdal region of the During the survey of brachyuran crabs in the intertdal Andaman Islands. It is a symbiotc crab that lives with regions of the South Andaman Islands, from December sea urchins of the genus Echinothrix. This species is 2014 to September 2018, a single male specimen of E. recorded from the Lakshadweep (Prakash et al. 2012) pentagonus was collected in December 2015 at Corbyn’s and Nicobar Islands (Sastry 1981) but there is no record Cove, Port Blair (Figure 1). The specimen was found in from mainland India. A detailed descripton of the rocky substratum in a free-living state. Afer collecton, it species, high quality photographs and line diagrams are was preserved in 10% bufered formaldehyde. Standard provided. literature (Chia et al. 1999; Ng & Jeng 1999) were All eumedonines (subfamily Eumedoninae, family referred for identfcaton of the species. Photographs Pilumnidae) are obligate symbionts of echinoderms and morphological measurements were taken with the (Castro 2015). Eumedoninae consists of a total of 33 help of a stereo zoom microscope (Leica M 205A). The species under 13 genera (WoRMS 2019). The genus specimen was deposited in the Department Museum, at Echinoecus under this subfamily contains three species, Pondicherry University, Port Blair. Echinoecus nipponicus Miyake, 1939, E. pentagonus (A. Material examined: One male collected from Port Milne-Edwards, 1879), and E. sculptus (Ward, 1934) (Ng Blair Coast, Andaman Islands; locality: rocky intertdal et al. 2008). They are commonly called ‘sea urchin crabs’ region, Carbyn’s Cove (11.6570N, 92.7530E); collected on as they are obligate symbionts of sea urchins. Echinoecus 14 December 2015 by Balakrishna Meher and T. Ganesh; pentagonus has a wide distributon, from eastern Africa dt.02.i.2019, deposited at Museum of Department DOI: htps://doi.org/10.11609/jot.4909.11.13.14773-14776 | ZooBank: urn:lsid:zoobank.org:pub:FD3CE19C-5168-459C-99E7-18AC389D3DFC Editor: A. Biju Kumar, University of Kerala, Thiruvananthapuram, India. Date of publicaton: 26 October 2019 (online & print) Manuscript details: #4909 | Received 21 February 2019 | Final received 24 August 2019 | Finally accepted 10 October 2019 Citaton: Meher, B. & G. Thiruchitrambalam (2019). A new distributon record of the Pentagonal Sea Urchin Crab Echinoecus pentagonus (A. Milne-Edwards, 1879) (Decapoda: Brachyura: Pilumnidae) from the Andaman Islands, India. Journal of Threatened Taxa 11(13): 14773–14776. htps://doi.org/10.11609/ jot.4909.11.13.14773-14776 Copyright: © Meher & Thiruchitrambalam 2019. Creatve Commons Atributon 4.0 Internatonal License. JoTT allows unrestricted use, reproducton, and distribu- ton of this artcle in any medium by adequate credit to the author(s) and the source of publicaton. Funding: Pondicherry University. Competng interests: The authors declare no competng interests. Acknowledgements: The authors are thankful to the authorites of Pondicherry University for providing the necessary facilites to carry out this work and University fellowship to Balakrishna Meher. The authors are also thankful to the Zoological Survey of India Andaman & Nicobar Regional Centre, Port Blair for the help in microscope facility. 14773 New distributon record of Pentagonal Sea Urchin Crab Meher & Thiruchitrambalam of Ocean Studies and Marine Biology, Pondicherry between the ischium and merus; a vertcal groove on University, Port Blair (PU/MB/501). the ischium and a large pit on the merus (Figure 2b). Surface of chelipeds smooth; upper margin of palm with Taxonomy a blunt spine at its distal end; carpus with one inner Order Decapoda Latreille, 1802 and one outer spine, outer spine reduced; merus with a Infraorder Brachyura Linnaeus, 1758 single spine (Figure 2f, g). Walking legs smooth to poorly Family Pilumnidae Samouelle, 1819 pited, unarmed and subcylindrical; dactylus thorny, Subfamily Eumedoninae Dana, 1852 inner margin with a small bunch of bristles (Figure 2h). Genus Echinoecus Rathbun, 1894 Anterior porton of thoracic sternum comparatvely narrow; sutures between sternites 1 and 2 indistnct, 2 Echinoecus pentagonus (A. Milne-Edwards, 1879) and 3 well defned, between 3 and 4 interrupted (Figure (Image 1, Figure 2) 2d). Abdomen with seven distnct segments (Figure 2e). First gonopod stout and S-shaped. Descripton: Carapace almost pentagonal in shape; Stevcic et al. (1988) established Eumedonidae Dana, length of carapace slightly more than width; surface 1853 as a distnct family whereas Ng & Clark (2000) without hairs, granules and very weakly punctuate when recognized Eumedonine as a subfamily of Pilumnidae observed under microscope; anterior surface of carapace family. with white margin and two almost vertcal white bands In the present study, the classifcaton of Eumedonine on the posterior surface (Image 1a, Figure 2a); diferent is based on recent standard literature (Ng & Clark regions of carapace surface weakly marked; antero- 2000; Ng et. al. 2008) and considered as a subfamily and postero-lateral margins well defned. Rostrum of Pilumnidae. The three species of genus Echinoecus elongated, bend downward and with a depression on look very similar. Sharp and longer rostrum of E. centre of it (Figure 2c). Pterygostomial and sub orbital pentagonus readily diferentates it from E. nipponicus regions pited in large amount (Figure 2b). Antennules and E. sculptus. E. pentagonus is the only member of obliquely folded (Figure 2b). Basal segment of antenna its genus represented from the coastal waters of India. rectangular. External maxilliped quadrate; rectangular Though it is mostly exclusively obligate symbiont with ischium and almost squarish merus; oblique suture diadematd sea urchins (Castro 2015), in the current Figure 1. Sampling locaton of Echinoecus pentagonus (Herbst, 1801) at Carbyn’s Cove, Port Blair, South Andaman Island. 14774 Journal of Threatened Taxa | www.threatenedtaxa.org | 26 October 2019 | 11(13): 14773–14776 New distributon record of Pentagonal Sea Urchin Crab Meher & Thiruchitrambalam a b e c d f g h Figure 2. Echinoecus pentagonus: a—dorsal view | b—ventral view | c—lateral view of rostrum | d—anterior porton of thoracic sternum | e—abdomen | f—cheliped | g—palm of cheliped | h—walking leg. study it was found in a free-living state, without a host, 1971). Therefore, it is very important to understand in the rocky intertdal region. It may be due to