Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Tergipedidae from New Zealand waters

Four species of the genus Cuthona Alder & Hancock are recorded for the first time. Two of these species are Cuthona beta (Baba & Abe, 1964) and C. alpha Baba & Hamatani, 1963: although the local specimens differ in some features, principally ceratal arrangement, length of the radula and colour, the differences are considered too slight to warrant separation. The other two are new, being distinguished by a combination of features: C. scintillans sp. nov. by the large size reached (24 mm), rhinophores, oral veil and number of ceratal rows (13), the rounded foot-angles, green diverticula and yellow surface pigmentation, and number of denticles on the largest radular teeth (9); C. reflexa sp. nov. by the simple colouration, short radula (30 teeth), terminal position of the cusp, a very short or no vagina and the renal opening above the anus.
The name Tergipedidae (= Cuthonidae) is given priority and its use reviewed. Three subfamilies are recognized viz. Cuthonellinae, Cuthoninae and Tergipedidinae, each founded on the division of the digestive gland. Thirteen genera are listed, but only seven are firmly established as being distinctive and belonging to the family; one of the remaining six, Guyvalvoria Vayssiere, 1906, is certainly valid, but, because the ceratal arrangement is only superficially known, its place in the family could not be determined.     

Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Glaucidae from New Zealand waters

Two new species of aeolid, a new genus being created for one of them, are described along with another two species, one Phidiana militaris (Alder & Hancock) (= Learchis militaris ) a new record for New Zealand, the other, Glaucus atlanticus , found only once before. Jason mirabilis gen. et sp. nov. is distinguished by a ventral tongue-like process with a ridged chitinous covering which replaces the radula (still present but vestigial) and by the greatly subdivided rhinophoral lamellae. Babaina caprinsulensis sp. nov. differs from its Californian relative in having papillate rhinophores. The New Zealand specimens of Phidiana militaris differ slightly in colouration from those described for elsewhere in the Indo-Pacific.
The Glaucidae is enlarged to include the Babainidae, Facelinidae and Favorinidae, the main familial characteristics being the simple oral glands, sharp radular tooth and pugnacious behaviour. Possible evolutionary trends within the family based on the arrangement of the cerata and penial structure are traced out. The Babaininae, pleuroproctic with a notal ridge and irregular disposition of the cerata, is considered the most primitive subfamily and the Hervellinae, with cerata in single rows, the most advanced. The many facelinid genera previously recognized are reduced to two, Antionetta Schmekel and Phidiana Gray.     

Dorid nudibranchs from eastern Australia (Gastropoda, Opisthobranchia)

Collections of nudibranch gastropods made in 1968 are described. All the 18 eastern Australian species of doridaceans (excluding chromodoridiform species) obtained are illustra-ed and investigated anatomically, often for the first time since their original discovery over a century ago. A list of the dorid nudibranches reliably recorded from Australian waters (compiled by R. Burn) supplements the paper.     

Chromodorid nudibranchs from eastern Australia (Gastropoda, Opisthobranchia)*

Collections of nudibranch gastropods made in 1968 and 1969 are described. All the 11 eastern Australian species of Casella, Hypselodoris and Chromodoris obtained are fully illustrated by line diagrams, photographs and water-colours. Two species new for Australia are described, and nine others are re-described. A list of the chromodoridiform species reliably recorded from Australian waters concludes the paper.     

Phylogeny and evolution of corambid nudibranchs (Mollusca: Gastropoda)

Organismic diversity, as well as distributional and ecological patterns, can be fully understood in an evolutionary framework only. Reliable phylogenetic trees are required to ‘read history’, but are not yet available for most marine invertebrate groups. Molecular systematics offers an enormous potential, but still fails for ‘all‐species approaches’ on groups with species that are rare or occur in remote areas only, simply because there is no easily collectable material available for sequence analyses. Exploring morphologically aberrant corambid nudibranch gastropods as a case study, we assess whether or not morphology‐based phylogenetic analyses can fill this gap and produce a tree that allows a detailed view on evolutionary history. Morphology‐based parsimony analysis of corambids and potential relatives resulted in a well‐resolved and remarkably robust topology. As an offshoot of kelp‐associated onchidoridid ancestors, and obviously driven by the heterochronic shortening of life cycles and morphological juvenilization in an ephemeral habitat, the ancestor of corambids originated in cool northern Pacific coastal waters. A basal clade (the genus Loy) diverged there, adapting to live on soft bottoms under successive reversals of paedomorphic traits. The more speciose Corambe lineage radiated preying upon short‐lived encrusting bryozoa in a high‐energy kelp environment. Selection favoured transformation of the mantle into a cuticle‐covered shield, and successive paedomorphic translocations of dorid anal gills to the protected ventral side of the body, where compensatory, multiple gills evolved. Corambe species probably first colonized tropical American seas, and then radiated in worldwide temperate waters: this is explained by the excellent long‐distance dispersal abilities afforded by rafting on kelp, with the subsequent divergence of colonizers in allopatry. The competitive coexistence of Corambe pacifica MacFarland & O'Donoghue, 1929 and Corambe steinbergae (Lance, 1962) off California is the result of independent colonization events. The closing of the Isthmus of Panama separated the latter species from a flock that have radiated within warm Atlantic waters since then. Our case study shows that morphological structures, if investigated in depth, bear the potential for an efficient phylogenetic analysis of groups that are still elusive to molecular analyses. Tracing character evolution and integrating a wide range of geographic, biological, and ecological background information allowed us to reconstruct an evolutionary scenario for corambids that is detailed and plausible, and can be tested by future molecular approaches. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 585–604.     

Additional dextral triphorids (Mollusca: Gastropoda) from New Zealand

Abstract

Socienna maoria Finlay and Mendax duplicarinata Powell are referred to Metaxia Monterosato. Metaxia solitaria n.sp., Socienna cracens n.sp., and S. cracens regia n.subsp. are described. Additional range data are provided for Metaxia exaltata (Powell).     

New records of Conidae (Mollusca: Gastropoda) from the New Zealand region

Abstract

Conus howelli Iredale is recorded from New Zealand. C. howelli and C. raoulensis Powell are considered to be very closely related, and Kermasprella Powell is thus probably a svnonvm of Endemoconus Iredale. C. teramachii (Kuroda) and C. smirna Bartsch ' Rehder are recorded from off northern New Zealand, and the known range of C. kermadecensis Iredale is extended southward.     

Recent and Tertiary Seguenziidae (Mollusca: Gastropoda) from the New Zealand region

Abstract

The family Seguenziidae is represented in the New Zealand region by the following new species (fossil taxa asterisked): Seguenzia glabella*, S. prisca*, S. serrata*, S. conopia, S. fulgida, S. chelina, S. transenna, S. textilis, S. compta; Seguenziella (n.gen.) patula; Seguenziopsis (n.gen.) bicorona; Carenzia venusta, C. fastigiata; Thelyssina (n.gen.) sterrha; Ancistrobasis dilecta, A. regina; Fluxinella (n.gen.) lepida, F. lenticulosa, F. maxwelli*; Calliobasis (n.gen.) eos*, C. chlorosa, C. miranda.     

Eastern Australian Pleurobranchomorpha (Gastropoda, Opisthobranchia)

Collections of pleurobranchomorph gastropods made in 1968 are described, and compared with material in the British Museum (Natural History) and with live Mediterranean specimens examined in the Naples Aquarium. All the eastern Australian species obtained are illustrated by line diagrams. Three species new for Australia are described, one is transferred to another known species, and six others are re-described. A list of the 12 species (with synonyms) reliably reported for eastern Australian waters concludes the paper, together with a key for their identification.     

Phylogeography and phyloecology of dorid nudibranchs (Mollusca, Gastropoda)

Dorid nudibranchs exhibit a number of anatomical and physiological adaptations that reflect a complex evolutionary history. The lack of a fossil record means that all available information on the evolution of this group comes from phylogenetic evidence. Deep imbalances in the phylogeny of dorid nudibranchs indicates that this group has probably undergone random extinction events and subsequent speciation of derived lineages. Sister-group relationships between eastern Pacific, Atlantic and tropical Indo-Pacific taxa [(eastern Pacific, Atlantic) Indo-Pacific], repeated throughout several lineages of dorid nudibranchs, provide solid evidence of two consecutive vicariant events: (1) the closure of communication between the tropical Indo-Pacific region and the Atlantic and eastern Pacific, which began during the Oligocene–Miocene transition and was completed with the formation of the East Pacific Barrier, and (2) the rise of the Panama isthmus. The absence of solid dates for the effective isolation of the eastern Pacific and the central Pacific does not allow estimations of the time of diversification of dorid nudibranchs. Phylogenetic evidence indicates that omnivorism and de novo synthesis of chemical defences are probably the plesiomorphic conditions in dorid nudibranchs. It is also likely that all sponge-feeding cryptobranch dorids have a common ancestor, but other cases of sponge feeding in phanerobranch dorids have arisen independently. The numerous instances in which de novo synthesis was replaced by sequestration of chemicals from the prey are evidence of a great metabolic versatility in dorid nudibranchs.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 551–559.     

The introduced slugs of New Zealand (Gastropoda: Pulmonata)

Abstract

Eleven species of slug introduced into the New Zealand fauna are discussed: Testacellidae - Testacella haliotidea Draparnaud, 1801 (T. vagans Hutton, 1882 n.syn.); Arionidae - Arion intermedius (Normand, 1852), A. hortensis Férussac, 1819 (A. incommodus Hutton, 1879 n.syn.); Milacidae - Milax gagates (Draparnaud, 1801), M. budapestensis (Hazay, 1881), M. sowerbyi (Férussac, 1823); Limacidae - Deroceras reticulatum (Müller, 1774) (Limax molestus Hutton, 1879 n.syn.), D. panormitanum (Lessona & Pollonera, 1882), Limax maximus Linnaeus, 1758, Lehmannia flava (Linnaeus, 1758), L. nyctelia (Bourguignet, 1861). Of these, T. haliotidea, M. budapestensis, M. sowerbyi, D. panormitanum, and L. nyctelia are recorded from New Zealand for the first time. A key for the identification of these species is provided. Species thought to be doubtfully established are discussed, and a list is given of recent interceptions at New Zealand ports.     

Reproduction in some New Zealand Cymatiidae (Gastropoda:Prosobranchia)

The behaviour during reproduction of four species of New Zealand cymatiids is described revealing a year-long courtship period in Cabestana spengleri. Charonia species, Mayena australasia and Monoplex australasiae have only a brief period of courtship prior to egg laying. The female of all species remains with the egg mass until the embryos hatch. This period may be as long as three months in the case of Mayena australasia. Protection of the egg mass seems to be the reason for this brooding behaviour as development proceeds normally in the absence of the female. Anatomically, the genital system of these mesogastropods is approaching the condition seen in more advanced neogastropods particularly with regard to the female.     

Origins and relationships of primitive members of the Opisthobranchia (Mollusca: Gastropoda)

An examination of possible prosobranch precursors of opisthobranchs and pulmonates suggests that archaeogastropods are poor candidates, as they lack the complex female glands which characterize all higher gastropods. Similarities between members of the Rissoacea and Cerithiacea with the Opisthobranchia and Pulmonata are here considered to be a result of parallel evolution. Much of the basis for suggesting phylogenetic aRinities between members of these taxa hinges on the supposition that pyramidellids are opisthobranchs. This contention is questioned, as the euthyneurous nervous system and hermaphroditic reproductive system share weak structural and positional homologies with opisthobranchs. The range of morphological variation within the Pyramidellidae should be more thoroughly investigated, as this taxon is poorly known. The reproductive system of members of the Littorinacea is largely homologous with that found in the least derived opisthobranchs and pulmonates. This, when considered in conjunction with other morphological and palaeontological evidence, suggests that the least derived mesogastropods, the Littorinacea, provide a more precise model of the opisthobranch-pulmonate ancestor among living prosobranchs. The specialization of the digestive system in littorinaceans suggests that morphological divergence has taken place following the cladogenesis of these taxa, and that a direct ancestor/descendent relationship cannot be implied from extant littorinaceans. The status of Acteon and other acteonids as archetypal opisthobranchs is questioned. Moditication 01 all morphological systems, with the exception of the shell and mantle complex, diminish the position of the Acteonidae as ancestral opisthobranchs. Members of the Ringiculidae more closely approach the ancestral form, but have undergone modification, as well. No extant opisthobranch retains all plesiomorphic character states. For this reason, in addition to the fact that contusion exists as to the plesiomorphic conditions of some characters within the Opisthobranchia, a hypothetical ancestral opisthobranch is characterized. It appears that parallel evolution, which confounds the relationships of certain prosobranchs and opisthobranchs, is also evident within the Opisthobranchia. Much of the confusion that has surrounded the determination of phylogenetic relationships within the Opisthobranchia relates directly to the high incidence of parallelism throughout the subclass.     

A note on some sacoglossan penial styles (Gastropoda: Opisthobranchia)

A penial style is a hollow, cuticular extension of the vas deferens present in most sacoglossan sea-slugs and also in many eolids and some dorids. During copulation a style projects beyond the tip of the distended penis and is used to transfer sperm either by hypodermic injection, or by conducting the sperm to a bursa copulatrix. The flexible styles of bivalved gastropods are described for the first time and new details are given for some other sacoglossan styles. The evolution of penial styles and their uses in taxonomy are discussed.     

Substratwahlversuche mit Microhedyle milaschewitchii Kowalevsky (Gastropoda,Opisthobranchia: Acochlidiacea)

Zusammenfassung Microhedyle milaschewitchii Kow. aus einem sublitoralen Schellsandvorkommen bei Rovinj (Jugoslawien) bevorzugte in Zweifachwahlversuchen eine Korngröße von 0,5–2 mm, die mit 73,1% im natürlichen Substrat vorherrscht. Die Tiere verhielten sich zum Licht neutral und zeigten im Vergleich zu Protodrilus keine extreme Thigmotaxis. Sterile Sande werden ebenso wie getrockneter Sand gegenüber natürlichem Substrat abgelehnt, sind aber nach zehntägiger Inkubation mit Sandbakterien diesem gleichwertig. Zwischen bakterienhaltigem Quarzsand und Kalksand zeigte sich keine signifikante Präferenz. Für die Besiedlung eines Substrates scheinen optimale Korngröße und lebende Mikroorganismen maßgebend zu sein.

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Summary Microhedyle milaschewitchii Kow. obtained from a sublittoral shellsand near Rovinj (Yugoslavia) prefers a grain size range of 0.5 to 2 mm in simple-choice experiments. This fraction predominates in the natural substrate (73.1%). Light did not affect the behaviour of the animals which are much less thigmotactical than Protodrilus. Sterile sands are rejected when offered together with natural substrate, but are equally attractive after having been incubated with sand bacteria for ten days. Similarly dried sand is not accepted by the animals. There is no significant preference between quartz and chalk sands, both containing bacteria. Optimal grain size and living microorganisms apparently are essential for the colonization of a substrate.

     

The recent New Zealand species of Triforis (Gastropoda: Triforidae)

Paramendax apicina Powell and Mendax attenuatispira Powell are referred to genus Triforis Deshayes; T. antepallaxa, T. blacki, and T. tui are described as new; and a species close to the South Australian Triforis epallaxa (Verco) is recorded from New Zealand waters. Paramendax Powell is transferred from the Cerithiopsidae to the Triforidae as a subgenus of Triforis. It is suggested that the Recent South African Cerithiella nonnitens Barnard is referable to Triforis.     

Towards a phylogeny and evolution of Acochlidia (Mollusca: Gastropoda: Opisthobranchia)

The Acochlidia are unique among opisthobranch gastropods in combining extremely high morphological and ecological diversity with modest species diversity. The phylogeny of acochlidians has never been addressed by cladistic means, as their evolution has remained unknown. This study gives a first overview on more than 150 biological and morphological characters that are potentially useful for phylogenetic analysis. Based on 107 characters, a parsimony analysis (PAUP) was performed for all 27 valid acochlidian species together with 11 (plus two) outgroup taxa. The resulting strict consensus tree shows a moderate overall resolution, with at least some bootstrap support for most resolved nodes. The Acochlidia are clearly monophyletic, and originate from an unresolved basal opisthobranch level. The Acochlidia split into the Hedylopsacea (Tantulum (Hedylopsis (Pseudunela (Strubellia (‘Acochlidium’, ‘Palliohedyle’))))) and Microhedylacea (Asperspina (Pontohedyle, ‘Parhedyle’, ‘Microhedyle’, (Ganitus, Paraganitus))). The formerly enigmatic Ganitidae, resembling sacoglossan opisthobranchs by having dagger‐like rachidian radular teeth, are likely to be highly derived microhedylids. The paraphyly of some of the traditionally recognized family level taxa induced a preliminary reclassification. From the phylogenetic hypothesis obtained, we conclude that the acochlidian ancestor was marine mesopsammic. The colonization of limnic systems occurred twice, independently: first in the Caribbean (with the development of the small interstitial Tantulum elegans), and second in the Indo‐Pacific, with a radiation of large‐sized benthic acochlidian species. The evolution of extraordinary reproductive features, such as hypodermic impregnation by a complex copulative aparatus in hedylopsaceans, cutaneous insemination via spermatophores in microhedylaceans, and gonochorism in Microhedylidae s.l. (including Ganitidae), is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 124–154.