Indian Journal of Geo Marine Sciences Vol. 46 (06), June 2017, pp. 1098-1104 Comparative taxonomic evaluation of Thais species (Order: Gastropoda; Family: Muricidae) of Mollusca 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 genus 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 taxonomy 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 animal 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 animals 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.