Morpho-taxonomy
Thesis paper by : Dr. Sanu V Francis
Presented on : 14-10-2021
Summary
Morpho-taxonomy, genetic analysis and distribution of calanoid copepods from Lakshadweep and coastal waters of Southwest coast of India
The present study discusses the taxonomic position of the pelagic calanoid copepods (Zooplankton: Crustacea) from the lagoon waters of Lakshadweep and coastal waters of the southwest coast of India based on morphological and molecular approaches. The study was conducted from Agatti, Bangaram, Kavaratti, Kalpeni and Minicoy Islands of Lakshadweep from 2013 to 2016 on a seasonal scale and Oceanic and coastal waters of the southwest coast of India during spring intermonsoon 2015 and fall intermonsoon 2015 on-board FORV Sagar Sampada.
Zooplankton density of all the five islands ranged from 8 to 56 ind. /m 3 during various seasons. Sixty-two calanoid species under sixteen families and twenty-seven genera including one new species, two new records with redescriptions and their distinguishing characteristics are illustrated in this study. A total of 27 species 11 families and 15 genera have been identified from Lagoon waters. From the oceanic waters of Minicoy, 39 species 13 families & 18 genera were identified. Along coastal waters, 42 species, 16 families and 15 genera were identified. The most dominant calanoid family was Pontellidae in which 17 species were observed. Eucalanide becomes the second abundant with 8 species. Rhincalanidae, Scolecitrichidae, Lucicutidae, Pseudodiaptomidae, were least dominant in all seasons. The species Subeucalanus subtenuis, Centropages calaninus, Euchirella sp., Euchaeta indica Labidocera bataviae, Labidocera detruncata, Pontella denticauda, Pontella fear, Pontella sinica, Pontella spinipes & Pontellopsis herdmani not observed in the lagoon waters and dominant only in the oceanic waters of Minicoy and coastal waters along the southwest coast of India. A new species of the planktonic calanoid copepod genus Tortanus, subgenus Atortus is described from the lagoon area of Minicoy Island, The new species is included in the tropicus group, which is mainly distributed in the tropical and subtropical waters of South East Asia.
This study presents the results of a comparative analysis of 111 barcode sequences of 25 calanoid species including 85 barcode sequences of 17 calanoid copepod species not included in any previous study from the coastal and oceanic waters of the southwest coast of India. Critical morphological analysis coupled with molecular barcodes of calanoid copepods Labidocera madurae, Pontella sinica and P. spinipes from coastal waters of the southwest coast of India revealed their actual taxonomic status and unambiguous identification of these species from various marine waters. This work confirms that the molecular and morphological methods can be considered complementary and when applied in combination, constitute a powerful tool for identification with minimal errors not only of copepods in the Arabian Sea but in the adjoining marine areas; the results are the first step in building databases of sequences and update morphological identification keys. The present study provides an authentic database for future studies on copepods and related fishery oceanographic studies in coastal waters of the southwest coast of India.
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