9th SCiUS Forum

Title: Biodiversity of Acorn (Crustacea: Cirripedia) in Family in Eastern Thailand OB1_13_06 Field: Biological Sciences Author: Mr. Pisit Sanjan School: Piboonbumpen Demonstration School, Burapha University Advisor: Dr. Woranop Sukparangsi Co-Advisor: Dr. Salinee Khachonpisitsak Department of Biology, Faculty of Science, Burapha University

Abstract: Acorn barnacles are sessile belonging to order Lamarck, 1818. They widely distributed in the intertidal areas of tropical and temperate regions worldwide. In previous observation, three species in Family Chthamalidae Darwin, 1854: Euraphia depressa, Euraphia hembeli, and malayensis have been identified along the Gulf of Thailand and Andaman Sea. However, some regions in eastern Thailand is still underinvestigated. Thus, in this study, we aimed to delineate biodiversity of chthamalids from more sampling sites along the coastline of eastern Thailand including Chanthaburi, Chon Buri, Rayong, and Trat provinces. In addition, Chthamalids exhibit diverse shell plate patterns; hence, we investigated morphological pattern of cirri, setal types and mouth parts via light microscopy in combination with scanning electron microscopy (SEM) to provide better taxonomic identification. Based upon morphological characters of parietes-operculum, ultrastructure of arthropodal characters, here we report several new records of chthamalids and highlight the diversity of barnacles in genus Chthamalus along eastern coastlines in the Gulf of Thailand.

Keywords: acorn barnacles, Chthamalids, eastern Thailand, biodiversity

Introduction: Rock barnacles or acorn barnacles are the sessile marine which belong to the Superorder , the infraclass Cirripedia in the Crustacea. They distributed in the international areas of tropical and temperate regions worldwide. In their adult stage, they live by attaching on the rocky shore along the interdial zone and the substrates including natural substrates such as floating wood, kelps, marine veterbrate animals and artificial substrates e.g. ships, bottles, plastic bags. The family Chthamalidae in order Sessilia Lamarck, 1818 has established by Darwin (1854). In previous inspection, there are several publications about them. Chan et al. (2016) has announced 7 species of acorn barnacles in genus Chthamalus, C. anisopoma, C. fissus, C. hedgecoki, C. panamensis, C. newmani and C. alani from the north-eastern Pacific. He also documented morphological characters of shell plates, arthropodal characters and mitochondrial analysis of them. In the western Pacific, Indian ocean, Indo- Malaya, northern Australia, Vietnam, China, and Taiwan, some Chthamalus barnacles, C. chanllengeri, C. moro and C. malayensis, were reviewed by Newman & Southward (2003) and Chan et al. (2009b). Moreover, there are not only the study of Chthamalus species but acorn barnacles in the genus Euraphia, the another genus in family Chthamalidae also founded. In Thailand, Pochai et al. (2017) has noted acorn

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barnacles 10 species classified into 6 genera and 3 families (Balanidae, Chthamalidae and Tetraclitidae) across the Andaman sea and the Gulf of Thailand. The species in family Chthamalidae which has been reported, 2 Euraphia species, Euraphia depressa and Euraphia hembeli, and 1 Chthamalus specie, Chthamalus malayensis. Following this, in Thailand there are just 3 Chthamalid barnacles were recorded. As well as, in previous study, the taxonomic identification was only based upon the arthropodal characters using light microscope, yet there are some species which being difficult to classify by information via light microscope. Thus, our study aims to determine Chthamalid barnacles from the stations which have never been determined for new records of acorn barnacles in family Chthamalidae.

Methodology: This study is based upon material collected from the Gulf of Thailand Sea in eastern Thailand, at Khao Sam Muk and Nam Nao beach, Chon Buri province, Lan Sai beach and Ratchakarun beach, Trat province and Hin Krong beach and Chao Lao beach Chathaburi province, in January 2018. Samples were collected by hand picking and were transferred in to plastic containers containing 95% ethanol. In the laboratory, These specimens were preserved in 95% ethyl alcohol and examined by using a compound microscope and stereomicroscope and later selected for dissection. All taxonomically important characters, shell plate morphology, and arthropodal characters were dissected and investigated with LEO 1450 VP scanning electron microscope on gold-coated specimens at Microscopic Center, Faculty of Science Burapha University. To identify specimens, we used keys of Chan et al. (2009) and Chan et al. (2016). The final pictures were processed with Adobe Photoshop CS6 and Adobe Illustrator CS6. Abbreviations used to denote shell morphology and arthropodal characters are explained directly in figure captions.

Results: Systematics Superorder Thoracica Darwin, 1854 Order Sessilia Lamarck, 1818 Suborder Pilsbry, 1916 Superfamily Darwin, 1854 Family Chthamalidae Darwin, 1854 Subfamily Chthamalinae Darwin, 1854 Genus Chthamalus Ranzani, 1817

1 mm Chthamalus Alani, Chthamalus moro, Chthamalus panamensis, H in Krong beach, Chanthaburi Hin Krong beach, Chanthaburi Nam Nao beach, Chon Buri

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Chthamalus alani Chan, 2016 Figure 1

Fig 1. Chthamalus alani. A, maxilla. B, cluster of setae on maxilla. C, maxillule. D, mandibular palp. E, mandible. F, second, third and fourth teeth, pecten and inferior angle of mandible H, labrum. I, cutting margin of labrum showing the fine teeth. Scale bars in μm. Chthamalus moro Pilsbry, 1916 Figure 2

Fig 2. Chthamalus moro. A, mandible. B, fourth teeth, pecten and inferior angle of mandible. C, maxillule showing notch. Scale bars in μm. Chthamalus panamensis Pilsbry, 1916 Figure 3

Fig 3. Chthamalus panamensis. A, cirrus III showing of unequal rami, length of anterior ramus 1.5-2.0 times of posterior ramus. B, mandible with four major teeth. C, labrum, prensence of fine teeth on cutting edge and small teeth on inner surface. Scale bars in μm.

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Key to additional species of Chthamalid barnacles from eastern Thailand 1a Shell plates with ridges…………………………………………………...... Chthamalus moro 1b Shell plates smooth without ridge……………………………………………………………….2 2a Equal rami…..………………………………………………………………….Chthamalus alani 2b Unequal rami……..……………………………………...... Chthamalus panamensis

Discussion and Conclusion: The present study represents the new records of acorn barnacles in the Gulf of Thailand, eastern Thailand. In addition to, previous studies that report the new records of acorn barnacles across Thailand’s coasts including the Andaman Sea and the Gulf of Thailand (Pochai et al., 2017), we also report three additional species of Chthamalus barnacles. Our study documents the taxonomic description, morphological characteristics, illustrations, systematics, and identification keys for these three species. Taking everything in consideration, this report presents the information that can enlarge the study of species distribution of acorn barnacles in Thailand. In the future, the works with more sampling sites and further in- depth investigations using molecular approaches with the help of phylogenetic analysis will provide a much better view especially of the history of barnacles and intraspecific variation between sessile and that may inform new species from Thailand.

References: 1. Chan, B.K.K., Prabowo, R.E. and Lee, K.H. (2009). Crustacean fauna of Taiwan: barnacles, volume 1. KeeLung, Taiwan: National Taiwan Ocean University. 2. Chan, B.K.K., Chen, H.N., Dando, P.R., Southward, A.J., and Southward, E.C. (2016). Biodiversity and biogeography of chthamalid barnacles from the North-Eastern Pacific (Crustacea Cirripedia). PLoS ONE 11(3): e0149556. 3. Pochai, A., Kingtong, S., Sukparangsi, W. and Khachonpisitsak, S. (2017). The diversity of acorn barnacles (Cirripedia, Balanomorpha) across Thailand’s coasts: The Andaman Sea and the Gulf of Thailand. Zoosystematics and Evolution 93(1): 13-34. 4. Southward, A.J. & Newman, W.A. (2003). A review of some common Indo-Malayan and western Pacific species of Chthamalus barnacles (Crustacea: Cirripedia). Journal of the Marine Biological Association of the UK. 83. 797 - 812. 10.1017/S0025315403007835h.

Acknowledgements: This work was part of Science Classroom in University-Affiliated School supported by Ministry of Science and Technology and financially supported by Science Classrooms in University-Affiliated School Project (SCiUS) and the Research Grant of Burapha University through the National Research Council of Thailand (Grant no. 27/2017).

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