Cistopus platinoidus Sreeja, Norman & Kumar, 2015, sp. nov
Creators: name: Sreeja, Vijayamma
name: Norman, Mark D.
name: Kumar, Appukuttannair Biju
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Octopoda
Octopodidae
Cistopus
Cistopus platinoidus

description: Cistopus platinoidus sp. nov
(Figs. 1–3)
Material examined. Kerala, India, collected from commercial trawlers operating in a depth range of 50–100 metres; collected by V. Sreeja and A. Bijukumar. Holotype: 1M: 120.0 mm ML, 600.0 mm TL, ZSI/ WGRC / IRN / 2084, off Kollam, 8°54'N, 76°30'E, 100 m, 22 September 2010. Paratypes: Beypore: 11o10’N, 75o48’E: 1M, 150.0 mm ML, 830.0 mm TL, 16 February 2011 (DABFUK/MOL/ CEPH /33); 1M, 120.0 mm ML, 566.0 mm TL, 16 February 2011 (DABFUK/MOL/ CEPH /34); 1F, 108.0 mm ML, 628.0 mm TL, 16 March 2011 (DABFUK/MOL/ CEPH /35). Puthiyappa: 11o18’N, 75o44’E: 1M, 180.0 mm ML, 887.0 mm TL, 16 February 2011 (DABFUK/MOL/ CEPH /36); 1F, 114.0 mm ML, 635.0 mm TL, 16 March 2011 (DABFUK/MOL/ CEPH /37). Sakthikulangara: 8o55’N, 76o32’E: 1F, 105.0 mm ML, 512.0 mm TL, 1 March 2012 (DABFUK/MOL/ CEPH /38); 1F, 132.0 mm ML, 610.0 mm TL, 6 January 2012 (DABFUK/MOL/ CEPH /39).
Diagnosis. Medium-size to large species (ML to 180 mm) with short arms (3.0–5.0 x ML), with dorsal arms longest (1>2>3>4). Deepest web 16–20% of longest arm. Dorsal web sectors deepest (A>B>C>D>E). Normal arms with 102–194 suckers (male 60–194, female 78–172). Hectocotylised arm with 60–65 suckers. 2–4 enlarged suckers present in males on arms 1 and 2 (at level of 10–12th proximal suckers), diameter to 10.1% of mantle length (6.7–14.1%). Gills with 9–10 lamellae per demibranch. Third right arm hectocotylised. Ligula small (0.6–1.8% of arm length) with small but distinct calamus (25% length of ligula). Spermatophores around 70.0 mm long (60.0– 80.0 mm), approximately 60% of mantle length (44.4–66.7%). Eggs 6–9 mm, around 6.5% of mantle length (5.6– 7.6%). Base colour grey with preserved specimens acquiring a pinkish colour. Slightly darker on dorsal surfaces. Skin smooth with few, scattered low papillae. Supraocular papillae absent. Lateral mantle ridge absent.
Description. A total of eight specimens were identified as this species. The following description is based on four mature males and four mature females. Counts, measurements and morphological indices are presented in Tables 1 and 2.
Medium-size to large species (Fig. 1a, b); mantle length (ML) to at least 180 mm in males and 132 mm in females, total length to at least 887 mm; weight to at least 1500 g. Mantle ovoid to round, longer than wide (width 47.6–70.4% of ML). Head wide (19.4–42.1% of ML). Skin relatively soft. Eyes relatively small. Stylets present; thin and non-mineralised rods, length around 30% ML. Mantle opening wide, around 50% circumference of body at level of opening. Funnel large broad and conical, approximately 40% of mantle length (41.7–53.3% of ML). Funnel organ large, W-shaped, outer limbs approximately equal in length with median ones (Fig. 1d).
Mucous pouches present in oral surface of web close to mouth, mucous pores present at the level of 3rd to 4th proximal sucker (Fig. 1c).
Arms long, around 3–5 times mantle length (3.0–4.7 x ML). Arms of moderate width, sub-cylindrical along length, taper gradually to thin tips. Arm autotomy at base of arms absent. Dorsal arms longest, decreasing in length to ventral pair (1>2>3>4). Suckers in two rows, moderate sized in females, around 6.3% of mantle length (5.7– 6.4%); 2–4 enlarged suckers present in males on arms 1 and 2 (at level of 10–12th proximal suckers), up to 10.1% of mantle length (6.7–14.1%) (Fig. 2 a). Around 100–194 suckers on intact arms (males 60–194, females 78–172).
Webs of moderate depth (deepest webs 15.8–20.3% of longest arm). Dorsal webs deepest, ventral web shallowest (A>B>C>D>E).
Third right arm of males hectocotylised. Modified arm short, approximately twice mantle length (1.2–2.1 x ML) and around 70–75% length of opposite arm. Ligula small (0.6–0.8% of arm length); triangular with shallow groove (Fig. 2 b). Calamus small and distinct, around one quarter of ligula length (16.0–33.3% LL). Hectocotylised arm with 60–65 suckers. Gills with 9–10 lamellae on both inner and outer demibranchs, plus terminal lamella.
Upper beak (Fig. 2 c) with narrow hood, short, and blunt rostrum. Lower beak (Fig. 2 d, e) with narrow hood and moderate wings, the lateral wall not separated in posterior region. Radula (Fig. 2 f) with nine elements, seven transverse rows of teeth and two rows of marginal plates. Rachidian tooth large, leaf-shaped with one or two lateral cusps on each side of the medial cone. Lateral cusps in asymmetrical seriation migrating from lateral to medial position over two transverse rows. First lateral teeth small with one medial cusp; second lateral teeth with wide heel, one dagger-like cusp. Marginal teeth long with sabre-like cusp, short base. Marginal plates moderate in length.
Digestive tract (Fig. 3 a). Anterior salivary glands moderate, longest axis 36% of buccal mass length. Posterior salivary glands well developed, slightly larger than buccal mass length (16% in 180 mm ML male), approximately 70% of digestive gland length (68.5% in same specimen). Crop with distinct diverticulum present. Caecum with approximately one whorl. Intestine long. Digestive gland well developed. Ink sac small. Anal flaps present.
Male genitalia (Fig. 3 b). Terminal organ (“penis”) in mature males muscular hollow tube (29.2–46.7% of ML); curved with small diverticulum. Vas deferens duct long and coiled. Spermatophores (60–80 mm, 44.4–66.7% of ML), produced in low numbers (10–12 in spermatophore storage sac). Ejaculatory apparatus coiled, one third of spermatophore length. Sperm reservoir 50% of total spermatophore length.
Reproductive tract of female (Fig. 3 c). Distal oviducts long and thin. Oviducal glands without radiating chambers, wrapped in ligament. Eggs small (Fig. 3 d), mature ovarian eggs 6.0–9.0 mm long in material examined. Numerous, approximately 7,000 to 8,000 small eggs in mature female. Egg length around 6.3% of mantle length based on available material (ELI 5.6–7.0%). This relative egg size of less than 10% of mantle length supports the likelihood that hatchlings are small and planktonic (Boletzky, 1974), potentially enabling wide planktonic dispersal.
Colouration. Fresh specimens dark greyish in colour dorsally and light greyish ventrally. Specimens preserved in formalin appeared reddish-brown. Skin smooth, with few scattered low papillae on dorsal mantle. Supraocular papillae absent. Lateral mantle ridge absent.
Type locality. Off Kollam coast, Kerala, India, 8°54'N, 76°30'E, 100 m.
Distribution. Only known from off southwest coast of India.
Etymology. The name ‘platinoidus’ is proposed for the species in remembrance of the Platinum Jubilee celebrations (2013) of University of Kerala, India and the Department of Aquatic Biology and Fisheries (2014), University of Kerala, India.
Remarks. The new species reported here is readily distinguished from the three Cistopus species described to date (C. indicus, C. taiwanicus and C. chinensis) on the basis of sucker counts, the number and position of enlarged suckers in males, presence or absence of a calamus, web depths, egg size and distinctive colour markings (see summary in Table 3). Differences in relative ligula length require further investigation as the reported size of 2.4% for hectocotylised arm length in C. chinensis (Zheng et al. 2012) is not supported by the scale on the illustration in this work and no raw data or range is presented for examined males.
Comparison of Cistopus platinoidus sp. nov. with C. indicus available in Indian coastal waters and collected during the present study shows distinct variations in normal arm sucker count (78–194 versus 185–206), hectocotylized arm sucker count (60–65 versus 107–127), enlarged suckers in males (absent in C. indicus), ligula length (0.6–1.8 versus 0.5–0.7), and calamus (absent in C. indicus) (Figs. 4 a, b). Comparison with C. taiwanicus specimens (Figs. 5 a–b) recorded for the first time from Indian coastal waters during the present survey recorded variations in hectocotylized arm sucker count (60–65 versus 106–116), enlarged suckers in males (2 at level of 10– 12th proximal versus 2 at level of 18–21st proximal suckers in C. taiwanicus), ligula length (0.6–1.8 versus 0.3– 0.6), and calamus (absent in C. taiwanicus) (Table 3). Further, the variations from C. chinensis are evident in web depth (15.8–20.3 versus 2.2–12.9), Normal arm sucker count (78–194 versus 81–126), enlarged suckers in males (2–4 on arms 1 and 2 at level of 10–12th proximal suckers versus 1–2 on arms 1, 2 and 4 at level of 10–11th proximal suckers), egg length (6–9 versus 5–7), egg number (7,000–8,000 versus 135), and iridescent lines and dots on dorsal mantle (present only in C. chinensis).
In India, benthic octopuses form the basis of economically important fisheries. The reported landings of octopods in 2012, 2013 and 2014 were 9,761, 6,448 and 5,909 tonnes respectively, representing about 5% of the total mollusc landings (CMFRI 2013, 2014, 2015). In Kerala state, from where the new species has been collected, the reported octopus catch in 2012 was 6,515 tonnes, forming 15.3% of total mollusc landings. Approximately 95% of octopus landings were collected by trawlers, with a reported catch rate of approximately 1.2 kg per hour. This trawl fishery includes Amphioctopus neglectus (51.4%), A. marginatus (25.4%), Cistopus indicus (18.6%) and unidentified or unspecified octopod species (18.6%) (CMFRI, 2013). Historically all species in the Cistopus species complex in India have been considered to be Cistopus indicus, though recent studies including the present one have shown that there are three species represented in the catch: C. indicus, C. taiwanicus and the new species described here. Due to the popularity of octopuses as a food source and their prevalence in artisanal and small-scale coastal fisheries, it is likely that reported catch statistics significantly underestimate the total octopod catches in the region.
Members of the genus Cistopus are highly prized as fisheries targets throughout their range, with at least one species, C. chinensis, being reported as suffering declines from overexploitation (Zheng et al. 2012). Clear species identification and delineation, collection of critical biological data (particularly reproductive data), population estimations and introduction of fishery management practices are all required to ensure sustainable harvests of these high profile and valuable species.
It is clear that further research is required into the diversity, distributions and fisheries value of members of the genus Cistopus, both in Indian waters and across the full range of the genus.
* range and raw data not presented in Zheng et al. (2012)
** calculated from raw data presented in Zheng et al. (2012).
description: Published as part of Sreeja, Vijayamma, Norman, Mark D. & Kumar, Appukuttannair Biju, 2015, A new species of pouched octopus, Cistopus Gray, 1849 (Cephalopoda: Octopodidae) from the southwest coast of India, pp. 244-256 in Zootaxa 4058 (2) on pages 245-255, DOI: 10.11646/zootaxa.4058.2.6, http://zenodo.org/record/236469