Indian Journal of Geo Marine Sciences Vol. 46 (06), June 2017, pp. 1098-1104

Comparative taxonomic evaluation of Thais species (Order: ; Family: ) of from Maharashtra coast of India

Ravi Kumar1, A.K. Jaiswar1, S. Jahageerdar1, S.K. Chakraborty1, A. Pavan Kumar1 & Laxmi Prasad2

1Central Institute of Fisheries Education (ICAR), Mumbai, Maharashtra - 400061, India 2Narendra Dev University of Agriculture & Technology, Kumarganj, Faizabad, U.P. -224229, India

[Email- [email protected]]

Received 17 December 2014 ; revised 15 November 2016

Based on shell morphology alone, it was difficult to differentiate the species belonging to Thais because of large amount of plasticity, observed in the shell characters. The colour of the shells was poorly defined as species identifying character in Thais species. The morphometric and meristic characters of the shell along with radular characters can solve the taxonomic ambiguities in Thais species (Thais lacera; T. blanfordi; T. tissoti; T. rudolphi; T. bufo and T. subnodulosa). The radular morphology was found to be different in each species except in T. rudolphi and T. blanfordi and hence these two species were differentiated based on radular morphology where the first denticle on outer base of the lateral cusp was smaller than other five denticles in T. rudolphi but in T. blanfordi, all were same in size. A deep ‘V’ shaped notch was present between inner denticle base of lateral cusp and central cusp in T. blanfordi, which was found to be a species specific character. [Keywords: Thais, Muricidae, Gastropods, Mollusca, radular]

Introduction 5 Molluscs have been evolved about 500 of phylogeny for Thaidid gastropods . In India million years ago during the Cambrian period1. molluscan fishery is contributing significantly in Among the classes of Mollusca, Gastropoda is total marine fishery. They form an important part most diverse group consisting of 80 per cent of all of food of coastal population, in preparation of the molluscs numbering to around 80,000-100,000 decorative items and in lime industry, and are species. Appukuttan, reported 3271 species important link in marine food web. However, the belonging to 220 families and 591 genera, previous studies did not explain in detail including 1900 species of gastropods, 1100 for majority of Thaidids, which aid to pelecypods, 210 cephalopods, 41 polyplacophores differentiate them easily. In view of this, the and 20 scaphopods from India2. Among the present study attempted to describe the gastropods, muricids shell exhibits highest degree identification of six Thais species occurring along of variations with regards to shell morphology and the Maharashtra coast of India based on shell sculptural patterns, which demonstrate its morphology and radular structure. 3 evolutionary importance . Materials and Methods Taxonomic studies of the gastropods have For the present study, a total of 177 specimens been carried out by researchers using shell belonging to six different species of Thais morphology, sculpture, micro-structure, radula comprising of Thais lacera (41); T. blanfordi (50); and anatomical characters, operculum structure T. tissoti (50); T. rudolphi (20); T. bufo (10) and and meristic counts. In Thais species the radula T. subnodulosa (6) were collected from different is stenoglossan (rachiglossan) type and usually coastal areas, Juhu Kolivada, Bandstand, Aksa has three cusps and smaller denticles. Radular beach, Versova beach, Shrivardhan, Alibaug and characters have also been widely used in species Ratnagiri along the Maharashtra coast of India. diagnosis4,and, considered as valid indicators The species were identified by using identification

INDIAN J. MAR. SCI., VOL. 46, NO. 06, JUNE 2017 1099 keys and publications1, 2-10. A total of seven removal of out of shell without any morphometric characters, shell length (SL), shell damage. In case of any difficulty to draw out the width (SW), body whorl length (BWL), aperture animal from shell, the shells were kept in deep length (APL), aperture width (APW), shell weight freeze at -200C for 24 hours resulting in shrinkage (SWT) and animal weight (AWT) were measured of muscle part. It is necessary to thaw them for from the collected specimens. Similarly, four 15-20 minutes in tap water before pulling out meristic traits like number of whorls (NW), animal from frozen shells. Subsequently the number of primary spiral cords bearing extracted were washed and cleaned nodules/tubercles on body whorl (NPBW), thoroughly; an incision was made on dorsal number of ridges or teeth inside of outer lip of the surface of the head with the help of scalpel and aperture (NRL) and number of tubercles in first scissor, a few millimetres away from the base of spiral row on shoulder of body whorl bearing tentacles or mouth opening to expose out radular nodules/tubercles (NT) were counted. The length sac. The sac was lifted out carefully with the help (mm) variables were measured using digital of forceps and transferred to 20% NaOH solution. Vernier callipers and weight (g) with a digital Later the solution was boiled for 5-8 minutes at weighing balance. 1000C in order to dissolve the attached tissue that resulted in release of radula into the solution. The

radula was picked up from solution with the help of forceps and washed in distilled water and absolute alcohol for 2-3 times to dehydrate and clean the radula. For further examination, the radulae were mounted on a clean glass slide with a drop of glycerine and examined under compound microscope. The radula was photographed by fixing the target at maximum resolution with provided zooming power (10X & 40X) followed by fixing the lens of digital camera on the eyepiece of compound microscope.

Fig 1. (A). T. Lacera (i). six whorls, (ii). two spiral ridges on body whorl bearing strong triangular tubercles. (B) (i). two grooved sulcus instead of anal sulcus, (ii). Well developed umbilical chink; (2). T. rudolphi (C) (i).five whorls, (ii). Five primary spiral cords on body whorl, (D) (i).primary spiral cords bearing alternate brown and white nodules; (3). T. subnodulosa (E) (i).six whorls, (ii). A white spiral strip between third and fourth spiral cords on body whorl (F) (i). four Fig. 2 Characteristics of radula, 1. T. blanfordi, 2.T. bufo, 3. T. lacera, 4. T. rudolphi, 5. T. subnodulosa and, 6. T. tissoti ridges or teeth inside of outer lip of the aperture; (4). T. tissoti (G) (i).five whorls, (ii). secondary grooved spiral cords in between of the cc- central cusp, lc- lateral cusp, idlc- inner each primary spiral cord on body whorl, (H) (i). four primary spiral denticle on lateral cusp, mc-marginal cusp, d- cords, (ii). five ridges or teeth inside of outer lip of the aperture; (5). denticles between marginal and lateral cusp.

T. bufo (I) (i).five whorls, (ii).two primary spiral cords bearing blunt tubercles; (6). T. blanfordi (J) (i).five whorls, (K) (i). ). six ridges or teeth inside of outer lip of the aperture. Statistical analysis PROC MEANS procedure (SAS Institute, Extraction of radula 2012) was used to estimate the descriptive Live specimens were anesthetized by injecting statistics. PROC FREQ procedure was used to 7.5% of MgCl2 to relax, loosen the muscles create frequency and cross-tabulation tables for attached to the inner shell surface, facilitated easy meristic traits.

1100 KUMAR et al.: COMPARATIVE TAXONOMIC EVALUATION OF THAIS

Table.1: Descriptive statistics of the morphometric traits Species Statistics Variable T. subnodulosa T. tissoti T. lacera T. rudolphi T. blanfordi T. bufo SL 18.25±1.306 18.15±0.400 41.82±1.367 45.18±3.134 26.03±0.373 38.64±3.893 BWL 12.23±0.745 9.84±0.282 29.99±1.043 37.08±2.481 18.22±0.281 32.22±3.723 SW 9.27±0.769 11.31±0.189 26.65±1.006 28.45±1.752 15.42±0.207 27.16±3.413 Mean±SE OPL 10.49±0.637 9.40±0.299 24.97±0.713 33.60±2.209 15.55±0.207 29.52±3.417 OPW 3.46±0.279 5.12±0.128 11.33±0.364 14.09±0.887 6.76±0.118 12.97±1.641 SWT 1.78±0.401 1.12±0.088 13.19±1.0458 13.49±2.035 3.09±0.125 12.71±4.588 AWT 0.19±0.030 0.16±0.011 2.17±0.154 3.68±0.682 0.36±0.015 3.31±1.620 SL 14.23 10.84 25.55 27.14 19.11 27.14 BWL 9.92 6.86 18.75 20.91 14.58 20.91 SW 6.85 7.14 17.02 17.04 12.18 17.04 Minimum OPL 8.42 6.31 17.19 19.49 12.75 19.49 OPW 2.66 3.67 7.42 6.62 5.06 6.62 SWT 0.63 0.21 2.58 2.94 1.35 2.94 AWT 0.10 0.06 0.87 0.59 0.14 0.59 SL 21.78 26.27 58.76 70.57 29.83 60.85 BWL 13.97 14.97 41.54 53.07 21.96 53.89 SW 11.41 15.92 39.68 41.58 19.05 47.56 Maximum APL 12.19 14.75 32.91 47.65 18.45 47.61 APW 4.31 7.39 15.72 20.07 8.32 22.49 SWT 3.19 3.59 22.43 35.92 4.59 47.31 AWT 0.27 0.39 4.07 8.83 0.56 15.91

Where, SL (Shell Length), SW (Shell Width), BWL (Body Whorl Length), APL (Aperture Length), APW (Aperture Width), SWT (Shell Weight) and AWT (Animal Weight)

Table 2. Comparative statement of meristic traits of Thais species Characters T. T. T. T. T. T. lacera bufo tissoti rudolphi blanfordi subnodulosa No. of whorls 5-6 5 5 5 5-6 6 No. of tubercles 7-11 9-11 10-14 12-13 9-11 10-12 in first spiral cord on shoulder of the body whorl

No. of primary spiral 2 2 or 4 4 3-5 2-4 4 cords on body whorl bearing tubercles

No. of ridges or teeth 0 0 4-5 26-29 4-8 4-5 inside of outer lip of the aperture

No. of inner lateral 1 1 1 1 1 1 denticles (radula)

No. of denticles 5 7 3 6 6 1 between lateral and marginal cusps

Colour Plain grayish light Light Chocolate Light chocolate or yellowish brown brown, brown with brown, brown with tan, inside of to gray with white spaces interior dark brown aperture pale in dark between white, dark tubercles orange colour brown beads on the blotches on tubercles beaded cords columella and aperture and aperture columella whitish white INDIAN J. MAR. SCI., VOL. 46, NO. 06, JUNE 2017 1101

Results fourth row of tubercles, visible inside of the Based on our present findings six species of aperture. Aperture with four to five denticles, the Thais are described below. posterior two denticles lead to raised ridges inside the aperture. Spire consists of five angulated T. lacera (Born, 1778) Fig. 1(A & B) whorls, with two spiral cords of compressed Shell with 5-6 whorls, body whorl largest. tubercles on each whorl. Body whorl bears 4-5 Secondary spiral cords (8-12) present between spiral chords of compressed round tubercles. first two well developed tuberculated primary Axial sculpture with 8-9 axial ribs. Denticles 4-5 spiral keels on body whorl. Umbilical chink inside of the outer lip of aperture. Columella with surrounded by a broad thickened rim. Aperture 2-3 anterior plications just above the siphonal ovate, inside of the outer lip smooth and siphonal canal; siphonal canal short and narrow; anal canal short. Two grooved sulcus present instead of sulcus deep, inverted ‘U’ shaped. Colour: Shell anal sulcus, where keeled spiral ridges ended on chocolate brown with dark brown tubercles, outer lip. Colour: Shell surface plain greyish or Interior of aperture violet in colour. Columella yellowish tan, inside of aperture pale orange, with dark brown patch posteriorly, anterior juveniles had darker lines in grooves on inner side portion violet in colour. of the outer lips. Central cusp of radula was thin, needle The radula with a triangular pointed central shaped; 1 or 2 denticles present between lateral cusp; lateral cusps bear single inner lateral and central cusps; single marginal denticle. denticle; edge of the inner lateral denticle Marginal cusp absent. serrated; base of the inner lateral denticle wider, five denticles present between marginal and T. tissoti (Petit, 1852) Fig.1 (G & H) lateral cusps. The length of lateral cusp about half Spire elevated, body whorl large and oblong. of the total length of central cusp. Aperture narrowly ovate, outer margin crenulated, inside of the outer lip with 4-5 ridges, columella T. rudolphi (Lamarck, 1822) Fig. 1 (C&D) smooth plicated anteriorly, margined posteriorly Shell thick with large body whorl, aperture by ridge, anal sulcus deep inverted ‘U’ shape. The more expanded with a short siphonal canal, four sculpture of body whorl consists of 4 thick spiral whorls, short conical apex, spiral growth lines ridges with bisulcate grooves and two narrow well developed and aperture canaliculated both cords in between of primary spiral ridges the ways. Surface sculptured with spiraled, widely ornamented with low tubercles, umbilicus small beaded cords with plain spiral cords between. almost closed; anterior canal short. 10-14 Columella almost straight, a longitudinal deep tubercles present in first spiral row on shoulder of notch in middle region of anterior portion of the body whorl. Colour: Light brown with dark columella is present. 4-5 flat but feebly raised brown tubercles and aperture brownish white in spiral ridges on the body whorl, alternatively colour. banded with white and dark brown nodules. Outer Central cusp of radula triangular in shape and lip thin, inner surface finely grooved in brown and short; single inner denticle; four small pointed yellowish line with the outer fine spiral ridges. denticles between lateral and marginal cusps.The Columella and parietal wall heavily calloused and lateral cusps extending toward marginal cusp. yellowish in colour but, inner margin of columella Marginal cusp short and blunt. towards aperture dark brown in appearance. Umbilicus reduced. Colour: Chocolate brown with T. bufo (Lamarck, 1822) Fig.1(I & J) white spaces between beads on the beaded cords; Shell thick, globose in shape, heavy and solid aperture and columella white. with short spire; body whorl largest with blunt Six denticles present between lateral and spines. Aperture large and canaliculated on both marginal cusps; first denticle on outer base of the anterior and posterior sides; columella broad, lateral cusp smaller than other five denticles; a smooth and extended beyond upper extremity of single inner lateral denticle; central cusp straight outer lip. Umbilicus well developed and and pointed. The base of lateral cusp wider than surrounded by thick umbilical chink. Aperture, central cusp. relatively broader than other thaidid shells. The body whorl liraeted with fine spiral cords and T. subnodulosa (Gravely 1942) Fig. 1 (E & F) spirally grooved structure. Outer lip margin Shell slender, spire longer than the body serrated, alternately marked by white and brown whorl; aperture opening narrow. The Body whorl spots but smooth inside. Body whorl wider, outer consisted of a white band between the third and lip thicker, tubercles comparatively well 1102 KUMAR et al.: COMPARATIVE TAXONOMIC EVALUATION OF THAIS

developed, widely spaced and less in number than Descriptive statistics of meristic traits T. rudolphi. Colour: The shell light brown to gray The number of primary spiral cords on body in colour. The rachidian cusp of radula sharply whorl bearing tubercles in T. tissoti and T. pointed; single inner lateral denticle pointed subnodulosa were similar but, the number of upward but slightly bent towards the lateral cusp. whorls was different. The number of primary Seven denticles between lateral and marginal spiral cords on body whorl bearing tubercles was cusps, of which the first two denticles on outer 2-4, 3-5, 2, 4, 2-4 and 4 in T. blanfordi, T. base of the lateral cusp poorly developed and rudolphi, T. lacera, T. tissoti, T. bufo and T. blunt (Fig 2). subnodulosa, respectively. Number of body whorls in T. tissoti and T. bufo were found to be T. blanfordi (Melvill, 1893) Fig.1 (K & L) similar but different in presence and absence of It neither pose bisulcate transverse groove nor ridges inside of the outer lip. They were also the revolving raised ridges of small nodules found to differ in number of the tubercles present equidistantly on the body whorl, as in T. tissoti. on first spiral cord. The tubercles present on Spire made up of 4-5 angulated whorls, body shoulder of the body whorl were 10-14 and 9-11 whorls with two spiral rows of compressed in T. tissoti and T. bufo, respectively (Table tubercles (9-11 in numbers), and two rows of 2).The number of primary spiral cords (4) and indistinct ridges, anal sulcus broad inverted ‘U’ number of ridges inside of the outer lip (4-5) was shape margined by ridge. Inside of outer lip with tissoti, but difference was seen in having six and 4-8 strong ridges, generally six, arranged in pairs. found to be similar in T. subnodulosa and T.five Anterior canal short and broadly open. Colour: number of whorls, respectively. T. lacera has Light brown, interior white, dark blotches on unique meristic character as presence of only two columella. keeled spiral ridges bearing strong triangular A deep ‘V’ shape notch between inner lateral tubercles and absence of ridges inside of the outer denticle and central cusp of radula. The central lip. cusp pointed and slightly curved towards the right side. Six small pointed denticles between The PROC FREQ procedure was applied for marginal and lateral cusp. meristic traits analysis revealed that in T. blanfordi 92% specimens were with 5 numbers of Descriptive analysis of shell morphometric traits whorls, while 88% of T. lacerahad6 numbers of The mean shell length in the present study whorls. In, other three species i.e. T. rudolphi, T. ranged from 45.17±3.13 mm in T. rudolphi to tissoti and T. bufo 100% specimens were with 5 18.14±0.29 mm in T. tissoti. The overall and numbers of whorls, while 100% specimens of T. species wise average of various morphometric subnodulosa had six number of whorls (Table 3). traits is presented in Table1.In the present study, it was observed that the species belonging to the Discussion genus Thais have different radular morphological Molluscs exhibit complex larval stages, frequent characters. The general radular formula for all cryptic taxa and substantial phenotypic plasticity; Thaidid species was same, having rachiglossan all factors hinder morphological approaches to type of radula consisting of one marginal cusp, identify Thais species11, 12. The phenotypic one lateral cusp and one central cusp, but plasticity in shell morphology which is common denticles present between lateral and marginal in molluscs poses additional problems for their cusps differed in each species. The number of proper identification and often leads to erroneous denticles between marginal and lateral cusps was results creating many synonyms and doubtful found to be different in all studied species except species. In the present study, colour of the shells in T. rudolphi and T. blanfordi, however, their of same species was found to be differed along radular morphology was different. The first with their change in habitats. However, the denticle on outer base of the lateral cusp was morphological features used most frequently for smaller than other five denticles in T. rudolphi, species identification, including size, shape and but in T. blanfordi all denticles were similar in the absence or presence of blotches on the nodules size. A deep ‘V’ shaped notch was present of shell surfaces and apertures etc. were highly between inner denticle base of lateral cusp and variable depending on the local environment. central cusp in T. blanfordi, which was found to be a species specific character.

INDIAN J. MAR. SCI., VOL. 46, NO. 06, JUNE 2017 1103

Table.3. Analysis of meristic traits by using PROC FREQ procedure

Frequency of the meristic traits

Species Species NW NPBW NRL NT 1 NO 5 6 2 4 4 6 8 9 10 11 Freq (92%) (8%) (12%) (88%) (8%) (82%) (10%) (74%) (20%) (6%)

2 NO 5 6 2 0 7 8 9 10 11 Freq (12%) (88%) (100%) (100%) (14.6%) (19.5%) (14.6%) (26.8%) (24.4%)

3 NO 5 3 4 5 26 27 28 29 12 13 Freq (100%) (10%) (30%) (60%) (20%) (10%) (15%) (55%) (40%) (60%)

4 NO 5 4 4 5 10 11 12 13 14 Freq (100%) (100%) (6%) (94%) (4%) (10%) (8%) (72%) (6%)

5 NO 5 4 0 9 10 11 Freq (100%) (100%) (100%) (50%) (30%) (20%)

6 NO 6 4 4 5 10 12 Freq (100%) (100%) (50%) (50%) (83.3%) (16.7%)

SPECIES - 1 (T. blanfordi), 2 (T. lacera), 3 (T. rudolphi), 4 (T. tissoti), 5 (T. bufo) and 6 (T. subnodulosa)

VARIABLES - NW (number of whorls), NPBW (number of primary spiral cords on body whorl), NRL (number of ridges inside of the outer lip) and NT (number of nodules/tubercles in first spiral row on shoulder).

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The above studied six Thais species were 3. Merle, D .& Houart, R., Recent progresses in identified based on the morphological and meristic muricid shell studies: challenge and future works. Bollettino Malacologia, Roma, 39(2004) 161-176. traits along with their radular structure. The 4. Claremount, M., Reid, D. G. & Williams, S. T., A identification of Thais species is therefore still molecular phylogeny of the and debated particularly on family and subfamily Ergalataxinae (: Muricidae). J. Mol. level. There are few genera under the family Stud., 74 (2008) 215-221. Muricidae i.e. Thais, Thaisella, Mancinella, 5. Kool, S. P., Significance of radular characters in reconstruction of Thaidid phylogeny Purpura, Drupa, Rapana and Indothais making (Neogastropoda: Muricacea). The Nautilus, 101 muricids difficult to be identified. (1987) 117-132. 6. Fernando, S. A.& Fernando, O. J., A field guide to Conclusion the common invertebrates of east coast of India, (Centre of Advanced Study in Marine Biology, The present finding will help in identification Parangipettei, T.N. India), (2002) pp 258. of Thais species. Though they are not important 7. Rao, N. V. S., Indian sea shells (Part-I): economically, occupy importance position in food Polyplacophora and Gastropoda, Rec. Zool. Surv. chain of in intertidal ecology, as food for demersal India, Occ. paper, 192(2003) 1-416. fishes. They also help in assessing the 8. Tan, K. S. & Sigurdsson, J. B., Two new species of Thais (Mollusca: Neogastropoda: Muricidae) from environmental quality and often used as indicator peninsular Malaysia & Singapore, with notes on T. species for many physicochemical parameters. tissoti (Petit, 1852) and T. blanfordi (Melvill, 1893) Therefore, these organisms should be protected, from Bombay, India. Raffles Bull. Zool., 44(1996) conserved and managed for sustainable 77–107. 9. Tan, K. S., Species checklist of Muricidae management of fishery resources. (Mollusca: Gastropoda) in the South China Sea. Raffles Bull. Zool. Suppl., 8(2000) 495–512. Acknowledgement 10. Tan, K. S. & Liu,L. L., Description of a new species of Thais (Mollusca: Neogastropoda: Authors are grateful to Dr. W.S. Lakra, Director Muricidae) from Taiwan, based on morphological Central Institute of Fisheries Education for his & allozyme analyses. Zool. Sci., 18(2001) 1275– encouragement and support during the study. 1289. 11. Drent, J., Luttikhuizen, P. C. & Piersma, T., Morphological dynamics in the foraging apparatus of a deposit feeding marine bivalve: phenotypic References plasticity and heritable effects. Functional Ecol., 18 (2004) 349-356. 1. Apte, D., The book of Indian shells,(Bombay 12. Marko, P.B. & Moran, A. L., Out of sight, out of Natural History Society, Mumbai, Oxford mind: high cryptic diversity obscures the identities University Press), 1998,pp. 115. & histories of geminate species in the marine 2. Appukuttan, K. K., Marine molluscs and their bivalve subgenus Acar. J. Biogeo., 36 (2009)1861- conservation, in: Marine Biodiversity: Conservation 1880. and management, edited by Menon, N. G. & Pillai, C. S. G., (CMFRI, Cochin) 1996, 66-79.