HAMINOEIDAE Pilsbry, 1895a

Bharate, Monisha, Oskars, Trond R., Narayana, Sumantha, Ravinesh, Raveendhiran, Kumar, Appukuttannair Biju & Malaquias, Manuel António E., 2018, Description of a new species of Haminoea (Gastropoda: Cephalaspidea) from India, with an account of the diversity of the genus in the Indo-West Pacific, Journal of Natural History 52 (37 - 38), pp. 2437-2456 : 2442-2448

Family HAMINOEIDAE Pilsbry, 1895a

Genus Haminoea Turton and Kingston [in Carrington], 1830

Haminoea aptei sp. nov.

( Figures 1 – 3 )

Diagnosis

Animal light olive with dark green blotches; mantle with brown, green and black dots, and fine white spots; cephalic deeply bilobed; visible eyes, unpigmented periocular area; Hancock ’ s organ, simple horizontal ridge. Shell pale yellowish, translucent; periostracum light orange to cream coloured; columellar lip thin, slightly reflected; columellar callus broad; outer lip, rounded, extends beyond apex. Jaws crescent shaped, formed by rodlet-like structures; ends of rodlets diamond shaped, with small indentations. Radular formula 18 × 6.1.1.1.6; rachidian tooth with three triangular cusps, larger central cusp; lateral teeth hook-shaped, smooth, tapering outwardly; inner lateral with broader cusp. Gizzard plate with 19 ridges; rachis present. Both upper sides of ridges and rachis covered by pointed rods; rods slightly sparsely distributed on top of ridges; absent on lower part of ridges. Male reproductive system with thick-walled atrium, thin-walled fundus; lower fundus narrow, upper fundus oval to bulbous; fundus filled with soft warts, forming vertical ridges, right side of upper fundus with larger, slightly pointed warts, separated by thick horizontal ridges and thin vertical ridges.

Type locality

Burmanallah , South Andaman, Andaman Islands, India (11.574511°N, 92.738906°E) .

Etymology

The species is named after Dr Deepak Arun Apte, current Director of the Bombay Natural History Society, India, for his excellent and dedicated work on the taxonomy of Indian Mollusca including opisthobranchs.

Material examined

India, Burmanallah , Andaman and Nicobar Islands (11.574511°N, 92.738906°E), 1 spc ., BNHS opistho 1343A (holotype), H = 6 mm, 24 March 2016; 26 spcs (6 dissected), BNHS opistho 1343/WII/NWR/ BNHS _9 (paratypes), H = 7.1 – 7.9 mm, 24 March 2016; 7 spcs (2 dissected, 2 sequenced), BNHS opistho 1344/WII/NWR/ BNHS _31, H = 6.0 – 8.2 mm, 8 March 2016 . India, Lakshadweep, Minicoy Island (8.27333333°N, 73.02638889°E), 3 spcs and 1 shell (2 dissected and sequenced), BNHS opistho 1361, H = 8 – 13 mm, 18 September 2014 .

COI barcodes

GenBank accession numbers MH 638603 ( BNHS opistho 1344), MH 638604 ( BNHS opistho 1344), MH 638590 ( BNHS opistho 1361), MH 638591 ( BNHS opistho 1361).

External morphology ( Figure 1 )

Animal light olive with dark green blotches; mantle with brown, green, black dots, and fine white spots. Cephalic shield broad anteriorly, laterally funnel-like structures present in some specimens only; tapering posteriorly, deeply bilobed, with cephalic lobes extending over anterior part of shell. Eyes visible, unpigmented periocular area.

Hancock ’ s organ simple, horizontal ridge. Parapodial lobes do not meet dorsally. Rounded pallial lobe, extends beyond apex.

Shell ( Figure 2 (a–c))

Shell, pale yellowish, translucent; periostracum light orange to cream coloured; shape cylindrical-elongate in smaller specimens (H = 6 mm) to oval in larger specimens (H = 8 – 13 mm). Aperture, broad anteriorly, tapers posteriorly; columellar lip thin, slightly reflected; columellar callus broad; outer lip rounded, extends beyond apex; shoulder rounded.

Jaws ( Figure 2 (d))

Crescent shaped, formed by rodlet-like structures; ends of rodlets diamond shaped, with small indentations.

Radula ( Figure 2 (e))

Radular formula 18 – 26 × 6 – 5.1.1.1.5 – 6 (based on three specimens with shell H = 7.9, 7.9, 8.2 mm). Rachidian tooth with three triangular cusps, central cusp larger. Lateral teeth hook shaped, smooth; inner lateral with broader cusp; outer laterals slimmer, tapering outwardly.

Gizzard plates ( Figure 2 (f–h))

Plates with 19 ridges. Rachis present. Both upper sides of ridges and rachis covered by pointed rods; rods slightly more sparsely distributed on top of ridges; absent on lower part of ridges.

Male reproductive system ( Figure 3 (a–c))

Consists of atrium, fundus, seminal duct and prostate. Atrium with thickened walls. Fundus with lower and upper parts, both thin walled; lower fundus narrow; upper fundus broader with variable shape, oval-elongated to bulbous; fundus filled with soft warts, forming axial ridges; warts tapers in size towards atrium; right side of upper fundus with larger, slightly pointed warts, separated by thick transversal ridges and thin axial ridges. Two retractor muscles; one connects seminal duct to mantle, the other to proximal region of atrium sheath.

Ecology

Rocky intertidal shores with cyanobacteria mats, green and red algae.

Distribution

So far only known from India in the Andaman and Nicobar Islands (Bay of Bengal) and Minicoy Island, Lakshadweep Islands ( Laccadive Sea).

Phylogenetic and species delimitation analyses

Both COI analyses (with and without third codon positions included) resulted in similar tree topologies, but the tree inferred from the data set with third codon positions included was better resolved with higher node supports ( Figure 4; Figure S1 ). This latter analysis suggests a possible 20 putative species ( Figure 4), whereas only16 were inferred

by the ABGD analyses ( Figure S2 ). Nevertheless, concerning the tropical IWP species, the focus of the current paper, both Bayesian COI analysis and ABGD were congruent in rendering 10 lineages.

The tropical Indian Ocean species H. natalensis represented by specimens from South Africa, United Arab Emirates and India received maximum support maximum support measured as posterior probabilities (PP) ( Figure 4, PP = 1) and was rendered sister to the West Pacific H. japonica Pilsbry, 1895b (also known to be invasive in the East Pacific coast of the US and Mediterranean Sea; Álvarez et al. 1993; Gosliner and Behrens 2006; Hanson et al. 2013) ( Figure 4, PP = 1).

Specimens of the colourful IWP species H. ovalis and H. cymbalum clustered together ( Figure 4, PP = 1), but the results suggest three species, namely H. cymbalum proper with representatives from the Philippines, Indonesia and Lakshadweep Islands ( India) as well as two cryptic species of H. cf. ovalis , one formed by specimens from the Philippines and Andaman Islands ( India), and the other one with a single specimen from Hawaii.

The remaining four IWP species formed a clade with maximum support ( Figure 4, PP = 1). This clade includes specimens from the Indian Ocean that match the description of H. pemphis ( Philippi, 1847) , here provisionally ascribed to the latter species which has its type locality in the Red Sea, two additional species represented by western Pacific specimens resulting from GenBank sequences ( Haminoea sp. 1 and Haminoea sp. 2 ), and a fourth species here described as new ( Haminoea aptei sp. nov.) based on specimens from the Andaman and Lakshadweep Islands off the western and eastern coasts of India.

Concerning only the IWP species, intraspecific COI genetic uncorrected p -distance varied between 0.25% for H. cf. ovalis ( India, Indonesia) and H. cymbalum and 2.8% for H. cf. pemphis . The new species here described, Haminoea aptei sp. nov. (see Taxonomic section), is 9.1% distant from its closest relative in the tree, namely the Western Pacific Haminoea sp. 1 from Indonesia and East Timor, and 18.2% distant from the chromatically similar Western Indian Ocean and sympatric species H. natalensis ( Figure 4 and Table 3).

Figures

Figure 1. Live specimens of Haminoea aptei sp. nov. (a) Andaman Islands (BNHS opistho 1344); animal length: 18.2 mm. (b) Minicoy Island, Lakshadweep Islands (BNHS opistho 1361); animal length: 23.0 mm.

Figure 2. Haminoea aptei sp. nov. (a) Apertural view (left image) and dorsal view (right image) (BNHS opistho 1361, H = 13 mm). (b) Apertural view (left image) and dorsal view (right image) (BNHS opistho 1343, H = 7.5 mm). (c) Apertural view (left image) and dorsal view (right image) (BNHS opistho 1344, H = 6 mm). (d) SEM, detail of jaw plate (BNHS opistho 1344). (e) SEM, detail of radula with central rachidian (BNHS opistho 1344). (f) SEM, surface of whole gizzard plate (BNHS opistho 1344). (g) SEM, detail of rachis and ridges (BNHS opistho 1344). (h) SEM, detail of ridge (BNHS opistho 1344). Scale bars: d, e, g = 20 µm; f = 100 µm; h = 5 µm.

Figure 3. Male reproductive system of Haminoea aptei sp. nov. (a) System with upper fundus on its rounded form (BNHS opistho 1344). (b) System with upper fundus on its stretched form (BNHS opistho 1343). (c) Detail of interior of fundus (BNHS opistho 1343). Abbreviations: smg, seminal groove; ga, genital aperture; at, atrium; as, atrium sheet; lfu, lower fundus; ufu, upper fundus; sd, seminal duct; pr, prostate; rm, retractor muscle. Scale bars: a, b = 1 mm; c = 0.5 mm.