Species check-list for Tintinnids of the Philippines Archipelago (Protozoa, Ciliophora)

Abstract Tintinnids are an essential link between nano- and macro- planktons in the food webs of the marine environment. It is also known that tintinnids are one of themajor components of marine planktonic ciliates and has a cosmopolitan character. In the Philippine archipelago, which is recognized as a center of marine biodiversity, tintinnids checklist has not been done or published. Therefore, a checklist is presented in this study based on a compilation of previous tintinnids studies conducted at the Philippines waters. As a result of the studies done since 1941 up to present, a total of 114 taxa belonging to 14 families and 37 genera were listed. The Philippines coastal waters record a total of 50 species while the open seas document 72 species to date.


Introduction
Microzooplankton (20-200µm) constitute a major component of the marine plankton community. Previously, the significance of microzooplankton (MZP) was commonly linked with microbial loop and corresponding microbial web Landry 2004, Calbet et al. 2008), but recent studies have shown that they also play a key role in the herbivorous food web (Dolan et al. 2007, Putland andIverson 2007). MZP graze a wide variety of particles from bacteria to nano-and phytoplankton as well as other similar organisms. They have a crucial role in the first feeding of the larval fishes (Stoecker andCapuzzo 1990, Fukami et al. 1999) and thus should be valued in the aquaculture industry. The awareness of the dynamic role of MZP in marine ecosystem resulted in the increase of scientific interest in the factors affecting their abundance and distribution. Research on microzooplankton arises as one of the vital parts of biological oceanography. In order to fully understand MZP behavior in different environments, a systematic qualitative study that includes listing of the species in a region is an essential step in exploring these organisms.
One of the best-known groups of marine microzooplanktonic ciliates is tintinnid (Kato and Taniguchi 1993). The distinctive characteristic of the tintinnid is its lorica, which has been the basis of their identification and classification. The easiness in identifying tintinnids based on their morphological features made them model specimens for research on species distributions, diversity, and variations in the structure of microzooplankton communities (Dolan and Gallegos 2001). Studies about the tintinnids distribution are essential due to the fact that they have been used as bio-indicators of different water massess (Kim et al. 2012). For example, the tintinnid species named Epiplocyloides reticulata (Ostenfeld & Schmidt, 1901) has been acknowledged as the Kuroshio water current indicator (Lee and Kim 2010). Records of E. reticulata are important to know the geographic extension of the warm Kuroshio current and the possible areas it can affect. A documentation of the tintinnid distribution is recognized as one of the best method to trace the flow of the water mass in open oceans and coastal waters (Lee and Kim 2010). In an archipelagic country such as Philippines, conducting tintinnid studies can be helpful in tracing different water masses and can aid in the assessment and management of its marine environment. However, tintinnids are poorly studied in the Philippines, a place which has been recognized as the center of the center of marine shore fish biodiversity (Carpenter and Springer 2005). A species-checklist for tintinnids specific for the Philippines can be a good starting point for any researcher who wants to conduct a tintinnid survey or any type of investigation in the country.. In order to assist other possible and future tintinnids studies in the Philippines, this present work aims to present the first and current checklist of tintinnid species in the Philippines. The authors also made this list to encourage other researcher to increase tintinnid studies in the Philippines. This study is based on a compilation of the literature to date.

Materials and methods
The Philippines archipelago is bound by the Bashi Channel to the north, the Philippine Sea to the east and northeast, the Celebes Sea to the south, the Sulu Sea to the southwest, and the South China Sea to the west and northwest side.
In this study, all published literature from 1941 to 2017 was examined. Taxonomical species and author names were written according to Roxas (1941), Gómez (2007), Kim et al. (2012) and Santiago et al. (2017).The study of Taniguchi (1977) was not included as a reference in enumerating tintinnid species since he only referred tintinnids as a group and his paper does not contain any detailed list of tintinnid species. The WoRMS (World Register of Marine Species) data system (Warren 2018) was used for classification and basis of the current species name. The species checklist in this study is alphabetically ordered.

Results
In related studies conducted in the Philippines, 114 tintinnid species belonging to 14 families and 37 genera have been recorded. The families Codonellidae (22 species, 19.30%) and Tintinnidae (21 species, 18.42%) have the highest recorded species ( The study of Roxas (1941) contained the first recorded tintinnid species in the Philippines. Roxas (1941) documented 32 tintinnid species wherein ten were newly discovered species (Table 2). Favella simplex, Favella philippinensis, and Favella elongata were the only accepted and registered species in the WoRMS database (Warren 2018) among the said newly discovered species. The other newly discovered species are still included in this present checklist due to the scarcity of tintinnid studies in the Philippines. The other newly discovered species were not recorded in any other studies and we took into consideration that they might be endemic in the area where Roxas (1941) collected them. Roxas also misspelled Leprotinntinnus nordqvistii, which he recorded as Leprotinntinnus nordquisti.
Since 1941, only three other studies (Gómez 2007, Kim et al. 2012, Santiago et al. 2017 were made in the Philippines that identified tintinnids to species level. The paper of Roxas (1941) and Santiago et al. (2017) recorded a total of 50 tintinnid species from coastal waters of Manila Bay (39 species) and Puerto Galera Bay (11 species). On the other hand, Gómez (2007) and Kim et al. (2012) conducted their sample collection within the Philippines open seas, which amounted to 72 tintinnid species.
Tintinnopsis, Codonellopsis, Coxliella, Metacylis, Rhabdonella, Epiplocylis and Eutintinus were the genera that both appeared in coastal and open waters (Table 1). There were eight genera that were only recorded in coastal waters and a total of 24 genera were solely found in the open seas (Table 1). Epiplocylis undella and Rhabdonella spiralis were the only species common to all of four tintinnid studies in the Philippines (Table 2).

Discussion
Presently, there are only four related studies (Roxas 1941, Gómez 2007, Kim et al. 2012, Santiago et al. 2017) that contain tintinnid species in the Philippines. Roxas (1941) and Santiago et al. (2017) conducted their zooplankton collection within the Philippines coastal waters while Gómez (2007) and Kim et al. (2012) had cruises along the open seas. Table 1 and 2 showed the tintinnids distribution between open seas and coastal waters. This is an important data because some of the tintinnids were categorized into biogeographical groups (Pierce and Turner 1993). The studies (Lee andKim 2010, Kim et al. 2012) that utilized tintinnids as indicator species used their biogeographical groups to assess water quality and mass movements. In this present study, there are species and genera that were only recorded in one area and some both appeared in open seas and coastal waters. Hence, the variation of the tintinnids distribution between open seas and coastal waters in this current work might help in further classification of tintinnid species to their biogeographical groups.
It should also be noted that each of the said four studies had a different sampling technique and effort. Roxas (1941) towed a no. 20 plankton net with 176 mesh per inch which means that it has an aperture of 0.076 mm or 76 µm. The plankton net that Santiago et al. 2017 used has 64 µm mesh size. These can indicate that the majority of the collected species of Roxas (1941) and Santiago et al. 2017 were large tintinnid species (>64 µm). Microzooplankton size range from 20 to 200 µm, thus, collecting tintinnids through plankton net with a relatively larger aperture size can result in loss of most of the smaller-sized tintinnids.
In the studies conducted in Philippines open seas, Gómez (2007) used Niskin bottles while Kim et al. (2012) towed a 20 µm mesh-plankton-net. The differences in methodologies and lack of standardization of sampling technique on tintinnids collection (Gómez 2007) can add complication on the analysis and comparison of   (Gómez 2007). The northeast (NE) was based on the study of Kim et al. (2012) in the Philippine Sea. The species in the Coastal areas were from Manila bay (MB) (Roxas 1941, Santiago et al. 2017 and Puerto Galera Bay (PG) (Roxas 1941). An asterisk (*) denotes new species.  their biogeographical distribution. Apparently, more studies on tintinnids in the Philippines and a standard of methodology should be established. The authors executed this current work to serve as a starting point for other researchers and encourage them to conduct studies on tintinnids in a center of marine biodiversity such as the Philippines.