Figure 2 - uploaded by Nathalie Yonow
Content may be subject to copyright.
Source publication
Seventy species of opisthobranchs are described in this work based on collections from the Persian Gulf, Socotra, Kenya, Zanzibar, Madagascar, La Réunion, Mauritius, the Seychelles, the Maldives, and Sri Lanka. Ten species are newly recorded from the western Indian Ocean and four species are recorded in the scientific literature for the first time...
Contexts in source publication
Context 1
... Fig. 2 (East Africa). Dolabella gigas. -Engel 1942: 197, figs. 1-5 ("Indian Ocean" and Mauritius + West Pacific); Eales 1946: 149, figs. 1-8 (Bombay, India) (syn. n.). Dolabella scapula (Martyn). -Engel 1942: 207, figs. 6-16 ("Indian Ocean," Mauritius, Mozambique + West Pacific). (Fig. 2) identifies the Zanzibar specimen as the tropical ...
Context 2
... Fig. 2 (East Africa). Dolabella gigas. -Engel 1942: 197, figs. 1-5 ("Indian Ocean" and Mauritius + West Pacific); Eales 1946: 149, figs. 1-8 (Bombay, India) (syn. n.). Dolabella scapula (Martyn). -Engel 1942: 207, figs. 6-16 ("Indian Ocean," Mauritius, Mozambique + West Pacific). (Fig. 2) identifies the Zanzibar specimen as the tropical Indo-Pacific Dolabella auricularia; the specimen had rounded tubercles in life, and these remain on the preserved animal. There are only two species of Dolabella, but to date no recent specimens of D. gigas (Rang) have been recorded. The two species are said to differ in shell morphology ...
Context 3
... form described and illustrated by Boettger, with five black patches on each side. This is the commonly occurring spe- cies in the Indian Ocean; see Yonow (1996) for descriptions, illustrations, and discus- sions. The white ring surrounding the black patch is visible in the preserved specimen and the oral tentacles are illustrated for comparison (Fig. 20A). The anterior margin of the foot is bilaminate, the head is visible, and the conical oral tentacles have a groove on their outer ...
Context 4
... tubercles aligned along edge. In Sri Lankan specimens, white submarginal line. Rhinophores deeper shade of orange than tubercles and margin, raised pocket rims also orange. Ventrally, foot of black and orange specimens deeply divided (convoluted for its entire margin in the largest specimen), head bipartite, separated oral tentacles digitiform (Fig. 20B), most similar to those of P. multituberculata form undula ( fig. 5B in Yonow 1996). In smaller, more relaxed, Maldive specimen (NY-167), thickened anterior margin of foot concave, head barely visible, oral tentacles ...
Context 5
... Dissection of the 28 mm Maldive animal shows that the digestive anatomy is typical for the genus (Fig. 20C). Significantly, it has a segmented asymmetrical pharyn- geal bulb as described and illustrated for P. multituberculata and P. m. form undula. This feature, in addition to the colour patterns, separates the Indian Ocean P. multituberculata from the Pacific P. ocellata Cuvier, which has a symmetrical pharyngeal bulb (e.g. Yonow 1996, ...
Context 6
... This juvenile specimen has identical marking to adult specimens, white with two black lines; dorsum completely smooth, tubercles not yet developed and spicules clearly visible in skin (Fig. 23A). Ventrally, minute tentacles same shape as in adults (Yonow 1996, figs. 11C, D), but no black pigment (Fig. 23B); gills and crevice between foot and hyponotum still black. Phyllidiella rudmani has a wide distribution from the eastern Indian Ocean to Japan in the western Pacific; it is currently only known from the Maldives in the ...
Context 7
... This juvenile specimen has identical marking to adult specimens, white with two black lines; dorsum completely smooth, tubercles not yet developed and spicules clearly visible in skin (Fig. 23A). Ventrally, minute tentacles same shape as in adults (Yonow 1996, figs. 11C, D), but no black pigment (Fig. 23B); gills and crevice between foot and hyponotum still black. Phyllidiella rudmani has a wide distribution from the eastern Indian Ocean to Japan in the western Pacific; it is currently only known from the Maldives in the central Indian Ocean. (Plate 71). Additionally, the two species differ ventrally, with P. striata lacking the black ...
Context 8
... still black. Phyllidiella rudmani has a wide distribution from the eastern Indian Ocean to Japan in the western Pacific; it is currently only known from the Maldives in the central Indian Ocean. (Plate 71). Additionally, the two species differ ventrally, with P. striata lacking the black pigmentation on the foot and oral tentacles (compare Fig. 22 and Fig. 24). Phyllidiella striata ranges from 13-35 mm while P. rosans is usually larger, measuring up to 52 mm (p. 67) and is much darker ventrally. Description. Living specimen very white and grey with two longitudinal black lines on each side of centre; each pair meets in front of its respective rhinophore. Outer black lines additionally meet ...
Context 9
... broad but thin mantle skirt. Central tubercles bead-like, arranged in three longitudinal lines; median one several tubercles wide. Skirt has scattered tubercles arranged neither in groups nor in lines. Anterior margin of foot narrow with thickened edge. Head distinctive, forming a "funnel" below broad fused oral tentacles, difficult to see in Fig. 25 (but similar to P. zeylanica); gills and head white in preserved ...
Context 10
... separated and long; the shape of the oral tentacles and the three dorsal ridges are more characteristic of Phyllidia varicosa or P. alyta although there is apparently no black line on the sole of the foot. Larger specimens of P. gemmata have perpendicular short black lines on the skirt (Pruvot-Fol 1957, Brunckhorst 1993 front of rhinophores (Fig. 26A) and extends to margin; posteriorly, they normally do not meet but bend outwards near the level of the anus and extend to the mantle mar- gin. Traces of black in between central tubercles, as well as spots and streaks on skirt. Anus protrudes in preserved specimens, located on edge of last tubercular cluster. Gills grey, fused oral ...
Context 11
... to margin; posteriorly, they normally do not meet but bend outwards near the level of the anus and extend to the mantle mar- gin. Traces of black in between central tubercles, as well as spots and streaks on skirt. Anus protrudes in preserved specimens, located on edge of last tubercular cluster. Gills grey, fused oral tentacles with black tips (Fig. 26B). Digestive anatomy typical of genus (Fig. ...
Context 12
... meet but bend outwards near the level of the anus and extend to the mantle mar- gin. Traces of black in between central tubercles, as well as spots and streaks on skirt. Anus protrudes in preserved specimens, located on edge of last tubercular cluster. Gills grey, fused oral tentacles with black tips (Fig. 26B). Digestive anatomy typical of genus (Fig. ...
Context 13
... three specimens from the Maldives proved to be identical (the fourth was badly preserved). One specimen (95 mm) everted its mouthparts completely during preservation (Fig. 27B, D). The mouth leads to a short oral tube which, in one speci- men, is narrow and contracted like a concertina (Fig. 27C). Where it thickens into the pharyngeal bulb, there is a band of pigment, incomplete dorsally. The pharyngeal bulb is extensible, as evidenced by the specimen illustrated in Fig. 27D. A sharp demarcation exists where the ...
Context 14
... three specimens from the Maldives proved to be identical (the fourth was badly preserved). One specimen (95 mm) everted its mouthparts completely during preservation (Fig. 27B, D). The mouth leads to a short oral tube which, in one speci- men, is narrow and contracted like a concertina (Fig. 27C). Where it thickens into the pharyngeal bulb, there is a band of pigment, incomplete dorsally. The pharyngeal bulb is extensible, as evidenced by the specimen illustrated in Fig. 27D. A sharp demarcation exists where the pharynx joins the bulb; the bulb turns anteriorly and loops posteriorly, passing through the nerve ring. The ...
Context 15
... mouthparts completely during preservation (Fig. 27B, D). The mouth leads to a short oral tube which, in one speci- men, is narrow and contracted like a concertina (Fig. 27C). Where it thickens into the pharyngeal bulb, there is a band of pigment, incomplete dorsally. The pharyngeal bulb is extensible, as evidenced by the specimen illustrated in Fig. 27D. A sharp demarcation exists where the pharynx joins the bulb; the bulb turns anteriorly and loops posteriorly, passing through the nerve ring. The posteriorly-directed portion is of equal length to the anteriorly-directed segment, and inserts into the oesophagus at a constriction. The oesophagus is a thicker banded tube leading into a ...
Context 16
... rationale behind this were de- scribed in Yonow et al. (2002). These specimens from the western Indian Ocean clearly conform to the original (and subsequent) illustrations of the species (erroneously iden- tified as Phyllidiopsis striata in the literature and on many websites) and further illus- trations are provided here of the anterior dorsum (Fig. 29A) and head/oral tentacles (Fig. 29B). It has an isolated distribution in the western Indian Ocean, from the Lac- cadive and Maldive islands south to Chagos and west to Mauritius, La Réunion, and Mayotte; there are no specimen records from East or South ...
Context 17
... in Yonow et al. (2002). These specimens from the western Indian Ocean clearly conform to the original (and subsequent) illustrations of the species (erroneously iden- tified as Phyllidiopsis striata in the literature and on many websites) and further illus- trations are provided here of the anterior dorsum (Fig. 29A) and head/oral tentacles (Fig. 29B). It has an isolated distribution in the western Indian Ocean, from the Lac- cadive and Maldive islands south to Chagos and west to Mauritius, La Réunion, and Mayotte; there are no specimen records from East or South ...
Similar publications
The following species of Gastropoda are recorded for the first time for Peruvian waters: Sthenorytis turbinus Dall, 1908, Crucibulum (Crucibulum) umbrella (Deshayes, 1830), Favartia (Murexiella) lappa (Broderip,1833), Cantharus (Cantharus) shaskyi Berry, 1959, Cantharus (Solenosteira) macrospira (Berry, 1957), Cancellaria (Bivetopsia) haemastoma So...
L’espèce du Cuisien de Gan (Pyrénées-Atlantiques) assignée à Pseudomalaxis planoconcavus (Rouault, 1850) par Cossmann (1923), n’est pas du tout la coquille pour laquelle Rouault a attribué ce nom. Nous donnons une nouvelle description de l’espèce de Rouault ainsi qu’une description de l’espèce nouvelle du Cuisien de Gan figurée par Cossmann. Des re...
Résumé
En août 2016, une étude a été menée sur la présence des Vitrinidae dans une partie du Parc national de la Vanoise. Dans la zone sud du Parc, vingt sites ont été échantillonnés. Des recherches ont été faites sur les animaux vivants et les coquilles vides. Les autres mollusques présents ont aussi été recensés. Au total, 39 espèces ont été obse...
Sea slugs in the broad sense (until recently called «opisthobranchs» and now within the Heterobranchia subclass of the Gastropoda),
have aroused the interest of naturalists since they began to be studied by the end of the XVIII century. Their colorful and varied shapes
make them very attractive to be studied and photographed. Numerous are the publi...
The population of Tropidophora fimbrata, a Mascarene endemic already extinct on La Réunion, has greatly increased on the Nature Reserve of Ile aux Aigrettes (Mauritius) during the last quarter century. This change follows the eradication of rats from the islet, the control of invasive alien plants and probably also the major drop in population of t...
Citations
... Investigations of the marine malacofauna started through expeditions and systematic works in 1832 in Mauritius (Tee et al., 2019). The latest inventory within the Western Indian Ocean dated a decade ago and denoted Mauritius and Reunion islands as the most diverse with 48 opisthobranch species (Yonow, 2012). ...
... 1888),Yonow and Hayward (1991),Yonow (2012), South West Indian Ocean (SWIO) website, this study (GenBank ID: OK482877)Yonow and Hayward (1991), Yonow (2012), Tibiriçá et al. (2017), South West Indian Ocean (SWIO) website, this study South West Indian Ocean (SWIO) website, this study Bergh (1888), Yonow and Hayward (1991), Yonow (2012), South West Indian Ocean (SWIO) website, this study (GenBank ID: MW817148) Yonow (2012), Tibiriçá et al. (2017), South West Indian Ocean (SWIO) website Bergh (1888), Yonow and Hayward (1991), Yonow (2012) Yonow and Hayward (1991), Yonow (2012), Tibiriçá et al. ...
Island ecosystems support diverse aquatic invertebrate communities comprising endemic taxa. Documentation of existing species is important for conservation. In this study, a checklist of marine opisthobranch from the Republic of Mauritius is presented. A combination of benthic surveys (50 m×5 m in triplicates), rover diving techniques and photo documentation were used over two years (2018–2020) within 35 sheltered and unsheltered lagoons. Morphological and molecular analysis were used for identification. Species composition within sheltered and unsheltered areas in Mauritius was estimated using the Bray-Curtis similarity. The checklist featured 117 species belonging to 61 genera and 28 families, of which 13 are new records. The findings increased the knowledge of opisthobranch diversity from the Mauritius by 15.4%. Among the listed species, the distribution range of Cyerce nigra, Actinocyclus papillatus, and Phyllidia picta extended from the Western Pacific to the South Western Indian Ocean. Molecular analysis of the undescribed Gymnodoris sp. showed it resembled Gymnodoris sp. from Hawaii and were different by a genetic distance value of 10.6%. The species richness and evenness were higher within the sheltered regions of Mauritius which harboured the food resource of opisthobranch. These areas as compared to unsheltered regions were heavily populated, suggesting the probable influence of wave actions on opisthobranch diversity and abundance. The order Nudibranchia was reported as most speciose, with 86 species. The Sacoglossa and Nudibranchia were observed only on macroalgae and sponges respectively. High abundance was also recorded on shipwrecks which are the most common form of artificial reefs. With the inclusion of observations from previous studies, 201 species belonging to 94 genera and 36 families are now known from the Mauritius.
... The naming history of N. yonowae is complicated and is clearly summarized by Pola et al. (2008), who considered N. guttata Yonow, 1994 as a junior synonym of N. yonowae. This species, with type locality in the Maldives Islands, was described by Goether and Debelius (1992), Yonow (1994Yonow ( , 2012 and Pola et al. (2008) for specimens of 40, 31, 35 and almost 60 mm long, respectively. In this size range, N. yonowae were described with black ground colour covered with strong orange-red pustules all over, 30% of them with a green border, black rhinophores with orange-red lamellae and rhinophoral sheaths bordered in orange. ...
... Nembrotha cristata Bergh, 1877 is very similar to N. yonowae, but all its pustules and pigmentation around rhinophores, oral tentacles, gill and foot are consistently green. This species has been reported mostly from the Western Pacific, with fewer observations in the Indian Ocean (Tanzania, Mauritius, Maldives Islands) (Yonow 1994, 2012, Pola et al. 2008, Anderson 2022. In most of its recorded distribution, N. cristata has been observed feeding on Sigillina signifera (Sluiter, 1909) (http://www.seaslugforum.net/ ...
In recent decades, thanks to the use of integrated taxonomy, the traditional recognition of a nudibranch species based on observation and colour pattern variation has become increasingly questioned, mainly due to the presence of cryptic and pseudocryptic species complexes. Individuals with the same colour pattern can be genetically identical, but individuals with different colour patterns may also be genetically identical and this variation may instead represent different life stages. But things can get even more complicated. What happens when the same species changes its colour pattern radically as it ages? Here we present two extraordinary examples in species of the genus Nembrotha based on laboratory observation. Specimens of Nembrotha livingstonei Allan, 1933 and Nembrotha yonowae Goethel and Debelius, 1992 were collected in Mozambique and kept in captivity as long as feeding was possible. The results showed that colour patterns in both species changed over time and that this change was linked to diet. Furthermore, species delimitation analysis and comparison of the uncorrected COI pairwise distances of examined specimens from Mozambique and others downloaded from GenBank confirmed that N. yonowae Goether and Debelius, 1992 is a junior synonym of N. cristata Bergh, 1877. Similar studies with laboratory observations are needed on other species of the genus, as they were described on the basis of different colouration, but integrated taxonomy may show different results.
... The species was re-described from material collected from Mauritius (Yonow and Hayward 1991), but Brunckhorst (1993) subsequently placed P. multituberculata as a synonym of P. ocellata. However, in later publications, four species of the ocellata complex were dissected: P. multituberculata was identified as a separate species from P. ocellata (Yonow 1996(Yonow , 2012, and deemed as occurring in the Indian Ocean (although its holotype locality was Indonesia). There are two colour forms reported for this species, the classic form (orange background colour with five large, tuberculate, black patches bordered by white; Yonow and Hayward 1991) and a black form (black background with orange tubercles; Yonow 2012) with the same segmented and asymmetrical pharyngeal bulb. ...
... Two muscle bands enter the bulb dorsally; the oesophagus is looped after exiting from the pharyngeal bulb. Remarks: The specimen collected from Lakshadweep Islands is almost identical externally to the specimens of Phyllidia multituberculata collected from the Maldives and Sri Lanka (Yonow 2012). The specimen in the present study was originally thought to be P. multituberculata due to its colour pattern and collection locality in the Indian Ocean. ...
... The Indian specimen was not only included in a clade with P. ocellata from the western Pacific Ocean region (Indonesia, Singapore, and Taiwan) but also had a symmetrical, uniform ( = unsegmented) pharyngeal bulb as do other Pacific specimens of P. ocellata (e.g., Domínguez et al. 2007;Yonow 1996Yonow , 2012. A review of the literature revealed that dissections of P. multituberculata having segmented pharyngeal bulbs are only recorded from the western Indian Ocean (P. ...
The current study presents the first molecular data of three species of the family Phyllidiidae, Phyllidia ocellata, Phyllidia alyta and Phyllidiella rosans, from Indian waters. The P. ocellata molecular sequences closely match those available from the Pacific Ocean, whereas P. alyta and P. rosans form independent clades, confirming their identifications as distinct species. Phyllidia ocellata, frequently found in the Indo-Pacific tropical coral reefs, is renowned for its wide range of colours and external forms. Numerous variations have been found and are being examined at the molecular level, and the subject of this study is another variation that, until dissection and molecular analysis, was thought to be a colour form of Phyllidia multituberculata. Although India has a long history of heterobranch research, no phyllidiid species from Indian waters have ever been the subject of molecular research.
... Collected specimens were photo-documented live whenever possible and preserved in 90% ethyl alcohol for further taxonomical studies. The opisthobranchs were identified with key references such as Alder & Hancock (1864), Apte (2009Apte ( , 2012, Debelius & Kuiter (2007), Yonow (2008Yonow ( , 2012, Gosliner et al. (2008Gosliner et al. ( , 2015, Venkataraman et al. (2015), and Apte & Desai (2017). The material was identified following descriptions provided by Kay & Young (1969), Gosliner et al. (2008) and Yonow (2008). ...
Opisthobranchs are the one of the least studied marine taxonomic group in Kerala. The present study was carried out to explore the opisthobranch diversity of rocky reefs of Kerala. And the study able to record the 13 species of sea slugs belongs to 3 Order 8 Families and 10 Genera. Out of 13 species recorded in the study, 8 species identified as new to Kerala coast. Among the 3 Orders recorded in the study Nudibranchia was noted with highest species contribution of 10 species and among the 8 families, the Dentrodoridae with maximum of 3 species.
... In this study, we focus on two of the six subclasses of gastropods: Heterobranchia, with a worldwide marine diversity of about 9000 species, and Vetigastropoda, with over 4000 extant species [18]. Heterobranch-specific studies from the Maldives include Eliot [10], Marcus and Marcus [19], Rudman [20], and Yonow [21,22], while no publication so far has specifically targeted groups of vetigastropods. ...
... COI sequence barcodes were also used for identification. Occurrence data for the entire Maldives were gathered from the Ocean Biodiversity Information System database (OBIS) [33] and literature records [9][10][11][12][13][14][15]19,[21][22][23]26,27,[34][35][36][37][38][39][40]. Maps and plots were built with the packages ggmap [41] and ggplot2 [42] in the R environment [43]. ...
... Yonow [21] stressed the significance of making new records of rare taxa available in the scientific literature, exemplifying with one sample of a sacoglossan from the Maldives [22], which turned out to be the only record for the entire Indian Ocean when the species was described a year later as having an Indo-West Pacific distribution [71]. Baseline biodiversity data, together with monitoring through time, are key resources for broader ecological and evolutionary studies, including evaluating the impact of environmental change. ...
Baseline biodiversity data are key for ecological and evolutionary studies and are especially relevant for areas such as the Maldivian Archipelago in the Indian Ocean, which can act as a stepping-stone for the transport of widely distributed marine species. We surveyed the islands and reefs of the Faafu and Malé Atolls with snorkeling and scuba diving, collecting the two gastropod subclasses, Heterobranchia and Vetigastropoda. Our inventory comprises 104 species photographed alive to create an identification guide. We also provide COI barcodes for most species, adding novel sequence data for the Maldivian malacofauna. Half of our species represent new records for the Maldives, emphasizing how much diversity remains to be discovered. Species distributions reflect ecological rarity, with almost 60% of taxa only found in one site. We also compiled a comprehensive checklist of heterobranchs and vetigastropods of the Maldives based on literature records, resulting in 320 species, which, together with barcoding data, indicate several potential cryptic species in the Indo-Pacific. Six new species are described, the nudibranchs Limenandra evanescenti n. sp., Eubranchus putnami n. sp., Sakuraeolis marhe n. sp., Moridilla maldivensis n. sp., Tergiposacca perspicua n. sp., and the sacoglossan Costasiella fridae n. sp.
... The genus Doriopsilla groups 24 accepted taxa, with D. areolata as the type species [14]. The distribution range of the different species included in the mentioned genus spans almost worldwide [10,15], as they occur in the shallow coastal waters of the Pacific coast of North America, Australia, Indo-Pacific, Persian Gulf, South and West Africa, Mediterranean Sea, European Eastern Atlantic, North American Western Atlantic, and Caribbean Sea [10,[15][16][17]. To date, three species are reported in the Mediterranean Sea: Doriopsilla areolata Bergh, 1880 [10,15]; D. evanae Ballesteros and Ortea, 1980 [18]; and D. pelseneeri d'Oliveira, 1895 [11] as Dendrodoris minima [15,[19][20][21][22][23][24]. ...
The Mediterranean Sea diversity is still far from being fully disclosed. Marine Hetero-
branchia are one of the most paradigmatic species-rich groups, with many recent systematic studies revealing the high density of new, cryptic, and endemic species occurring in the Mediterranean basin. In this study, sea slug Doriopsilla areolata, which was considered until today one of the most widespread nudibranchs worldwide, was investigated using a molecular approach to compare Mediterranean and Atlantic populations for the first time. The molecular analyses involved three different molecular markers, the two mitochondrial COI and 16S, and the nuclear H3 gene. The results revealed a complex of species within D. areolata that indeed consists of three potentially species, two of which are endemic to the Mediterranean Sea: Doriopsilla areolata, which is distributed in the Adriatic Sea (the type locality of the former species), D. rarispinosa, which occurs in the Western Mediterranean
basin and along the Tunisian coast, and one additional Atlantic species here provisionally defined as Doriopsilla sp. 1. This study helps to unveil another case of cryptic diversity within Mediterranean Heterobranchia and to increase the knowledge on Doriopsilla genus diversity.
... While Widespread in the Indo Pacific. Hawaii, Guam, Thailand (Jensen, 1992), Red Sea (Yonow, 1990), Zanzibar, Kenya, Maldives, Seychelles, Reunion, Mayotte (Yonow, 2012) Thuridilla hoffae (Gosliner, 1995) Western Pacific Ocean. Papua New Guinea, Japan (Gosliner, 1995) Thuridilla vataae (Risbec, 1928) Widespread in the Indo Pacific. ...
... Papua New Guinea, Japan (Gosliner, 1995) Thuridilla vataae (Risbec, 1928) Widespread in the Indo Pacific. New Caledonia (Risbec, 1928), Western Australia, Guam (Jensen, 1992), Indonesia, Papua New Guinea (Gosliner, 1995), South Africa (Gosliner, 1987), Reunion island, Maldives (Yonow, 2012) Family Oxynoidae Stoliczka, 1868 (1847) Oxynoe sp. ''jordani'' Philippines, Australia. ...
The opisthobranch are a diverse group of sea slugs sensitive to anthropogenic pollution. Considering the plans of Mauritius to expand the harbour, the present study investigated the distribution of opisthobranch in area of close proximity. A total of three survey areas (Bain des Dames, Rivière Noire and Le Morne) were monitored over a period of fifteen months (August 2019 to December 2020) using belt transects of 50 m × 5 m. Environmental variables such as nutrients (nitrate, sulphate, phosphate, organic matter, organic carbon) and heavy metals (chromium ⁵³Cr, iron ⁵⁷Fe, cadmium ¹¹¹Cd and ¹¹⁴Cd, tin ¹¹⁹Sn, mercury ²⁰²Hg and lead ²⁰⁸Pb) were measured. A total of 1367 opisthobranch belonging to 76 species and 20 families were recorded, with 13 novel records. Species richness was higher at Bain des Dames (H’ = 3.22) and Pielou’s evenness index fluctuated from December 2019 to June 2020 and in December 2020 at Le Morne. PERMANOVA analysis showed species composition depends on survey location, period and its complex interaction (p < 0.05). Most records were made during the breeding/spawning season (summer). The SIMPER analysis showed the Cephalaspideans were the dominant species explaining the dissimilarity between Bain des Dames and Rivière Noire (40.63%). Their observations possibly relate to feeding purposes since they feed on polychaete which inhabit fine grain and organic rich areas. The sacoglossans explained the dissimilarity between Bain des Dames and Le Morne (38.73%) and Rivière Noire (44.95%). Their abundance relate to their abundant food source. The three locations differed from each other, with concentration of environmental variables higher at Bain des Dames. The BIO-ENV matching analysis showed organic matter, organic carbon and depth (R = 0.328, p < 0.05) best explained the pattern in biotic assemblage. The findings show pollution is not affecting the population of opisthobranch. Their tolerance to nutrient enrichment suggest their valuable use as biological indicators.
... Six hundred and ten specimens were preliminarily identified with the help of available literature (Domínguez et al., 2007;Fahrner & Beck, 2000;Gosliner et al., 2018;Yonow, 2011Yonow, , 2012. Additional websites such as the Sea Slug Forum were used to check for external variability and distribution data. ...
... Fifty specimens of Phyllidia coelestis ( Fig. 4.2a-e) collected around Sulawesi exhibit the typical colouration as described by Brunckhorst (1993) and Yonow (2012). The animals all have three longitudinal black lines on the notum and a general bluish background that is granulated. ...
Members of the widely distributed and common nudibranch family Phyllidiidae are often easily spotted in the marine environment because of their conspicuous colours and obvious presence on the reef. They are interesting with regard to their defensive chemical compounds that may lead to new drug discoveries. Despite their abundance, the family is also well known for its taxonomic problems and the difficulties in species identification due to very similarly coloured species and lack of morphological characters. In this study, phyllidiid species were analysed using an integrative approach. Molecular analysis of the mitochondrial genes 16S and CO1 was utilised, running phylogenetic analyses, species delimitation tests, and haplotype network analyses. Additionally, for the first time, external morphological characters were analysed, museum material was re-analysed, and chemical profiles were applied for characterising species. The analyses are based on sequences of 598 specimens collected in Indonesia by the team, with the addition of published sequences available on GenBank. This study comprises 11 species of Phyllidia, seven species of Phyllidiopsis, and at least 14 species of Phyllidiella. Moreover, 11 species belonging to these three genera are probably new to science, Phyllidiopsis pipeki is synonymised with P. krempfi, and Phyllidiella albonigra is resurrected. Some of the external colouration previously used for species identification is shown to not be valid, but alternative characters are provided for most species. Chemical analyses led to species characterisation in a few examples, indicating that these species use particular sponge species as food; however, many species show a broad array of compounds and are therefore characterised more by their composition or profile than by distinct or unique compounds.
... Both Mauritius and Reunion islands have been ranked as having the most diverse heterobranch fauna in the Western Indian Ocean, with 48 species reported (Yonow 2012). Information on the biodiversity of sea slugs of Mauritius is also available on the South-West Indian Ocean Sea Slug Site (http://seaslugs.free.fr/ ...
... forum.net/), taxonomic works (Rudman 1985;Yonow , 1994Yonow , 2001Johnson and Valdés 2001;Yonow 2012;Yonow and Jensen 2018;Mehrotra et al. 2020), and the assistance of divers on social media. ...
To date, 179 species belonging to the gastropod infraclass Euthyneura are known from Mauritius. We report for the first time from Mauritius the chromodorid nudibranch, Hypselodoris infucata (Rüppell & Leuckart, 1830), based on 47 sites surveyed over 17 months. This species was previously known from the eastern Mediterranean Sea, Indo-Pacific Ocean, and Western Indian Ocean. We observed it in Mauritius at Bain des Dames near a shipwreck under coral rubble. Considering the small size and camouflage behavior of some nudibranch species, additional fieldwork will likely add others species unknown from the islands.
... Distribution. Plakobranchus ocellatus and P. cf. ocellatus are currently considered widespread across the Indo-Pacific including Kenya, Zanzibar, the Red Sea, Maldives, Seychelles, Réunion (Yonow 2012), India (Sheeja and Padma Kumar 2014), the Philippines (Christa et al. 2012), Indonesia (Eisenbarth et al. 2018;Yonow and Jensen 2018), Japan (Maeda et al. 2012), Australia, Papua New Guinea (Yonow and Jensen 2018), Guam (Wägele et al. 2011), Vanuatu (Krug et al. 2013), Hawaii (Wade and Sherwood 2016), Tanzania, Madagascar, Malaysia and Palau . Specimens considered as P. ocellatus have been previously recorded from the Andaman and Gulf waters of Thailand Nabhitabhata 2009). ...
... Distribution. Thuridilla gracilis sensu lato is known from Maldives, Seychelles (Yonow 2012), India (Apte 2009), Singapore (Jensen 2009), Myanmar (Sanpanich and Duangdee 2019), Indonesia (Yonow and Jensen 2018), Vietnam (Martynov and Korshunova 2012), Taiwan (Huang et al. 2016), Japan (Trowbridge et al. 2011), Australia Smith 2016), Madagascar, Malaysia, the Philippines, Papua New Guinea, Palau, New Caledonia, Guam, andFiji (Gosliner et al. 2008). Known from the Andaman and Gulf waters of Thailand Nabhitabhata 2009). ...
... Remarks. Recent work (Yonow 2012;Bazzicalupo et al. 2020), has indicated the need for morphological and molecular examination of S. longicauda across their range with the taxonomic validity of the species being questioned. In the present work, S. longicauda is treated as distinct from S. striatus based on differences in external morphology (consistently shorter papillae and yellow/lime-green colouration in S. longicauda) and ecology. ...
Improved access to field survey infrastructure throughout South-East Asia has allowed for a greater intensity of biodiversity surveys than ever before. The rocky bottoms and coral reef habitats across the region have been shown to support some of the highest sea slug biodiversity on the planet, with ever increasing records. During the past ten years, intensive SCUBA surveys have been carried out at Koh Tao, in the Gulf of Thailand, which have yielded remarkable findings in sea slug biology and ecology. In this work a brief history of sea slug biodiversity research from Thailand is covered and a complete inventory of sea slugs from Koh Tao, Gulf of Thailand is provided. This inventory is based on surveys from 2012 to 2020, with previously unreported findings since 2016. Habitat specificity and species-specific ecology are reported where available with a focused comparison of coral reef habitats and deeper soft-sediment habitats. The findings contribute 90 new species records for Thai waters (92 for the Gulf of Thailand) and report a remarkable consistency in the proportional diversity found to be exclusive to one habitat type or another. Additionally, taxonomic remarks are provided for species documented from Koh Tao that have not been discussed in past literature from Thailand, and a summary of previous records in the Indo-West Pacific is given.
