Introduction
The subfamily Ophelininae Hartmann-Schröder, 1971 under the family Opheliidae Malmgren, 1867 is comprised of six genera Ammotrypanella McIntosh, 1878 (six species), Antiobactrum Chamberlin, 1919 (single species), Armandia Filippi, 1861 (38 species), Ophelina Örsted, 1843 (61 species), Polyophthalmus Quatrefages, 1850 (10 species), and Tachytrypane McIntosh in Jeffreys, 1876 (single species) (Read and Fauchald, Reference Read and Fauchald2024). The genus Armandia is characterized by an elongate body, a ventral groove extending all along ventral side, conical prostomium with palpode, cirriform branchiae from the second chaetiger to posterior end, lateral segmental eyespots, simple parapodia with two bundles of capillary chaetae and anal tube. The anal tube is one of the major distinguishing features among the species of this genus, as its length, shape, opening, presence, and types of anal papillae varies among species (Moreira and Parapar, Reference Moreira and Parapar2017). In the Indian waters, five species of Armandia have been reported (Gopal et al., Reference Gopal, Abdul Jaleel, Parameswaran and Vijayan2016; Sivadas and Carvalho, Reference Sivadas and Carvalho2020) viz. Armandia intermedia Fauvel, 1902, A. lanceolata Willey, 1905, A. leptocirris (Grube, 1878), A. longicaudata (Caullery, 1944), and A. sampadae Gopal, Jaleel, Parameswaran & Vijayan, Reference Gopal, Abdul Jaleel, Parameswaran and Vijayan2016.
The genus Ophelina differs from the genus Armandia in the absence of lateral segmental eyespots along the body. The body is elongated with deep ventral groove, cirriform branchiae may be present or absent, parapodia are provided with capillary chaetae and pygidium bears a defined anal tube (Parapar et al., Reference Parapar, Al-Kandari, Barroso and Moreira2023). Under the genus Ophelina, only a single species i.e. Ophelina acuminata Örsted, 1843 has been recorded from Indian waters (Sivadas and Carvalho, Reference Sivadas and Carvalho2020).
The present paper describes a new species belonging to the genus Armandia and provides the first record of Ophelina arabica Parapar, Al-Kandari, Barroso & Moreira, Reference Parapar, Al-Kandari, Barroso and Moreira2023 from Indian waters (Figure 1).
Map of northern Indian Ocean, indicating collection locations of Armandia ramanamurthyi n. sp. and Ophelina arabica.
Materials and methods
As part of the Sea Water Quality Monitoring Programme, benthic sampling was conducted along the entire coastline of India covering western Bay of Bengal (August–October 2023) and eastern Arabian Sea (December 2023–January 2024) onboard CRV Sagar Tara and CRV Sagar Anveshika. A Van Veen grab (0.1 m2 bite area) was used to collect sediment samples at 2 and 5 km distance perpendicular from the coast in each transect. Sediment samples were sieved using 500 μm mesh sieve and residual samples were preserved in a 5% Rose Bengal formalin solution. Light microscopy observations and measurements were carried out using a Leica M205C stereo zoom microscope and Leica DM1000 LED compound microscope. Photographs were taken using a Leica Flexacam C3 camera attached to the stereomicroscope as well as compound microscope. Drawings of the holotype specimen of Armandia ramanamurthyi n. sp. were created using a Leica M Series drawing tube, attached to the Leica M205C stereo zoom microscope. Opheliid polychaetes were identified using taxonomic references (e.g. Fauchald, Reference Fauchald1977; Parapar and Moreira, Reference Parapar and Moreira2015; Moreira and Parapar, Reference Moreira and Parapar2017). All type materials are deposited in the reference collections of the National Centre for Coastal Research (NCCR), Chennai, Tamil Nadu, India. The accession number IO/NCCR/POLY/xxxx denotes IO-Indian Ocean, NCCR-National Centre for Coastal Research, POLY-Polychaeta, xxxx-accession number.
Results
Class POLYCHAETA Grube, 1850
Family OPHELIIDAE Malmgren, 1867
Genus Armandia Filippi, 1861
Armandia ramanamurthyi n. sp.
(Figures 1–7)
Armandia ramanamurthyi n. sp., holotype: (A) entire specimen, ventral view and (B) prostomium, anterior end, and palpode.
Armandia ramanamurthyi n. sp., holotype: (A) ventral mouth with oral papillae and (B) ventral view of body showing ventral cirrus.
Armandia ramanamurthyi n. sp., holotype. Parapodium from 18th chaetiger.
Armandia ramanamurthyi n. sp., holotype: (A) anal tube, ventral side and (B) anal tube, details of orbicular papilla bearing black pigmentation.
Armandia ramanamurthyi n. sp., holotype: (A) anal tube and posterior end, dorsal view and (B) anal tube, ventrolateral view.
Armandia ramanamurthyi n. sp., holotype: (A) entire specimen, ventral view; (B) anal tube, dorsal side; (C) parapodium from 18th chaetiger (left side) and (D) anal tube, ventral side.
Diagnosis
Prostomium with clavate tipped palpode. Prostomial eyes absent. Branchiae present from chaetiger 2 to 39. Lateral eyespots from chaetiger 7 to 28. Anal tube long, laterally compressed forming a ridge in ventral margin. Proximal end of anal tube provided ventrally with an orbicular papilla with black pigmentation on dorsal surface of bulbous portion; orbicular papilla ending in an oblique cirrus towards posterior end. Anal tube opening dorso-posteriorly without marginal papillae in the posterior margin.
Etymology
The species is named in honour of Dr. M. V. Ramana Murthy, Director, National Centre for Coastal Research (NCCR), Ministry of Earth Sciences, India. He is also serving as Mission Director for Deep Ocean Mission, India which is flagship initiative of the Government of India to explore and harness the resources of the deep ocean.
Material Examined
Holotype
India. Tamil Nadu: Marakkanam, TN4/2, 12°13.143′N, 80°0.871′E, 7.8 m, specimen complete, IO/NCCR/POLY/0001, 3.19 mm long and 0.18 mm wide, 40 chaetigers.
Paratypes
India. Tamil Nadu: Marakkanam, two complete specimens, IO/NCCR/POLY/0002, 3.51 mm long and 0.13 mm wide, 40 chaetigers; IO/NCCR/POLY/0003, 1.46 mm long and 0.08 mm wide, 40 chaetigers.
Description
Body slender, tapering towards anterior end, with a deep ventral groove all along body (Figures 2A & 7A). Prostomium conical with a clavate palpode (Figure 2B). Prostomial eyes absent. Nuchal organs present on lateral side of prostomium, as a U-shaped depression. Mouth ventral, three oral tentacles protruding from pharynx (Figure 3A). Branchiae long, even surpassing parapodium, starting from chaetiger 2 to 39. Branchiae marginally increasing in length from anterior to middle chaetigers and then marginally decreasing in length towards posterior chaetigers; branchial length variation not pronounced. Black, rounded lateral eyespots of the same size observed from chaetiger 7 to 28. Each parapodium with a conical chaetigerous lobe bearing two bundles of chaetae, a very short dorsal cirrus and a stalked spherical ventral cirrus (Figure 4). First chaetiger with a dorsal cirrus and ventral cirrus, both small and spherical, ventral cirrus stalked and spherical in consecutive parapodia (Figure 3B). Parapodia bearing two bundles of simple capillary chaetae (Figures 4 & 7C). Notochaetae longer than neurochaetae, comprising 7–8 long capillaries and 7–8 medium-sized capillaries; neurochaetae includes 7–8 medium-sized capillaries and 7–8 small-sized capillaries. Anal tube about 5.5 times as long as wide, as long as last eight chaetigers, laterally compressed forming a ridge in ventral margin, bearing 20–22 faint vertical bands in entire length (Figures 5A, B & 6A, B). A bulbous orbicular papilla-like structure ventrally and near to proximal region of anal tube (Figures 5A & 7D); orbicular papilla with black pigmentation on dorsal surface ending in an oblique cirrus towards posterior end; cirrus broken in the posterior end in both holotype and paratypes (Figure 5B). Anal tube opening dorso-posteriorly, posterior margin lacking marginal papillae (Figures 6A & 7B).
Distribution
Tamil Nadu, 7.8 m depth, sandy sediments.
Genus Ophelina Örsted, 1843
Ophelina arabica Parapar, Al-Kandari, Barroso & Moreira, Reference Parapar, Al-Kandari, Barroso and Moreira2023
(Figures 1 & 8A, B)
Ophelina arabica Parapar et al., Reference Parapar, Al-Kandari, Barroso and Moreira2023: 4–12, Figures 1–5.
Diagnosis
Body tubular with ventral and lateral grooves. Branchiae present from second chaetiger. Parapodia biramous with a rounded prechaetal lobe, ligulate ventral lobe and short spherical dorsal cirrus. Anal tube long, annulated, with a black pigmented, elongated, bump-like structure in ventral side of anal tube, fringed with a pair of small elongated papillae and an unpaired anal cirrus. Anal tube opening dorso-posteriorly, lacking marginal papillae.
Ophelina arabica Parapar, Al-Kandari, Barroso & Moreira, Reference Parapar, Al-Kandari, Barroso and Moreira2023: (A) entire specimen and (B) anal tube, lateroventral view.
Material Examined
India. Goa: GA3/2, 15°42′N, 73°40′E, 9 m, 3 complete specimens; IO/NCCR/POLY/0004, 2.58 mm long and 0.11 mm wide, 38 chaetigers, IO/NCCR/POLY/0005, 2.05 mm long and 0.11 mm wide, 38 chaetigers, IO/NCCR/POLY/0006, 1.93 mm long and 0.11 mm wide, 38 chaetigers.
Description
Body long, tubular, slender tapering anteriorly (Figure 8A). Ventral and lateral grooves extending from anterior to posterior end. Prostomium pointed and bearing a terminal palpode; prostomial eyes not observed. Nuchal organs oval, seen as deep lateral depressions. Branchiae long, starting from chaetiger 2 to last chaetiger. Biramous parapodia, with a rounded prechaetal lobe, ligulate ventral lobe and short spherical dorsal cirrus. Parapodia bearing two bundles of chaetae; chaetae as simple smooth capillaries, with 6–8 capillaries in each bundle. Anterior parapodia chaetae oriented laterally or postero-laterally. Notochaetae longer than neurochaetae, as long as branchiae. Notochaetae of posterior five chaetigers oriented latero-posteriorly and longer than those from anterior chaetigers, even surpassing anal tube. Anal tube as long as last 5–6 chaetigers, 2.5 times as long as wide, with 25–26 fine annulations. Anal tube opening dorso-posteriorly, without marginal papillae. Ventral side of anal tube bearing a black pigmented, elongated, bump-like structure in basal portion, fringed with a pair of small elongated papillae and an unpaired anal cirrus even surpassing anal tube. Ventral margin of anal tube fused, showing a pronounced ventral fusion line extending from anal cirri base to anal tube opening (Figure 8B).
Distribution
Kuwait (Parapar et al., Reference Parapar, Al-Kandari, Barroso and Moreira2023), India (present study); intertidal to 9 m, sandy substrate.
Discussion
Four species of Armandia lack papillae in the posterior margin of the anal tube viz. Armandia bilobata Hartmann-Schröder, Reference Hartmann-Schröder, Hartmann-Schröder and Hartmann1986, Armandia exigua Kükenthal, Reference Kükenthal1887, Armandia nonpapillata Jones, Reference Jones1962, and Armandia simodaensis Takahashi, Reference Takahashi1938. Armandia ramanamurthyi n. sp. is similar to all aforementioned species in the absence of posterior marginal papillae in the anal tube and differs from all aforementioned species in the presence of a black pigmented, bulbous orbicular papilla in the ventral proximal region of the anal tube.
In the Indo-Pacific region, three species of Armandia lacking papillae in the posterior margin of the anal tube have been reported. Armandia bilobata, described from sandy beaches of Port Hughes (Australia) bears an anal tube which opens ventrally and dorsally over the posterior half so that the bi-lobed back half resembles two wings. In A. ramanamurthyi n. sp. the anal tube is longitudinally closed and opens dorso-posteriorly. Lateral eyespots are double in number and branchiae are relatively more numerous in A. ramanamurthyi n. sp. than in A. bilobata (Table 1). Armandia bilobata is provided with three prostomial eyespots while those are absent in A. ramanamurthyi n. sp. Armandia simodaensis, reported from the beach sediments near Shimoda Marine Biological Station (Japan), possesses a horn-shaped delicate membranous anal tube while in A. ramanamurthyi n. sp. anal tube is tubular and relatively thick. Anal tube opens dorso-posteriorly and lacks prostomial eyespots in both species. The dorsal cirri are long and subulate in A. simodaensis but small and spherical in A. ramanamurthyi. Armandia simodaensis has fewer lateral eyespots and branchiae than A. ramanamurthyi n. sp. (Table 1). Armandia exigua from China bears a ventrally opened cylindrical anal tube, with a notch on ventral side of the anal tube as a continuation of abdominal groove whereas A. ramanamurthyi n. sp. bears a relatively long anal tube, closed all along its length and opens only dorso-posteriorly. Prostomial eyespots are absent in both species. The number and arrangement of lateral eyespots and branchiae and in chaetigers are detailed in Table 1.
Comparison of species of the genus Armandia Filippi, 1861 that lack anal papillae in the anal tube
NA, not available; NS, not specified.
In the North Atlantic Ocean, A. nonpapillata, reported from Kingston Harbour (Jamaica), bears ventrally an opened truncated anal tube whereas A. ramanamurthyi n. sp. bears a dorso-posteriorly opened anal tube. Armandia nonpapillata has elliptical segmental eyespots and ciliated branchiae while A. ramanamurthyi n. sp. possesses circular segmental eyespots and non-ciliated branchiae (Table 1); both species lack prostomial eyespots. The dorsal cirri are small and spherical in both species while ventral cirri are subtriangular in A. nonpapillata and spherical and stalked in A. ramanamurthyi. The report of the new species from Bay of Bengal increases the number of known Armandia species to six in Indian waters and 39 species globally.
The specimens of Ophelina arabica reported from Kuwait (Figure 1) and the present specimens from India are mostly similar apart from two features. In specimens of O. arabica from Kuwait (Parapar et al., Reference Parapar, Al-Kandari, Barroso and Moreira2023), the notochaetae of posterior five chaetigers do not surpass the distal end of the anal tube, while in Indian specimens, the notochaetae fairly surpass the anal tube. A reddish spot is present in distal end of anterior lobe of all parapodia in specimens from Kuwait whereas such spots were completely absent in Indian specimens. This new record of O. arabica from Indian waters extends its known geographic distribution from the Persian Gulf to Indian waters.
Data
All data generated during this study are included in this article.
Acknowledgements
The study was undertaken as part of the Sea Water Quality Monitoring (SWQM) project funded by the Ministry of Earth Sciences, Govt. of India. The authors are greatly indebted to Vessel Management Cell, National Institute of Ocean Technology (NIOT), for providing the facilities of CRV Sagar Tara and CRV Sagar Anveshika for conducting the scientific cruises. The authors extend gratitude to all onboard scientific participants, Varya Tech Private Limited engineer, and ship staff for supporting the sampling. Our gratitude goes to colleague Ms. Sasmita Swain for the drawings. This is NCCR contribution number 431.
Author contributions
A. G.: conceptualization, identification, and writing; S. K. S. and K. R.: writing – review.
Financial support
This work is carried out as part of Sea Water Quality Monitoring Project funded by Ministry of Earth Sciences, Govt. of India.
Competing interests
None.
Ethical standards
No animal testing was performed during this study.
