A new species of turtle-headed sea Snake (Emydocephalus: Elapidae) endemic to Western Australia

Sexual dimorphism in aipysurine sea snakes (Elapidae, Hydrophiinae)

The transition from terrestrial to aquatic life by hydrophiine elapid snakes modified targets of natural selection and likely affected sexual selection also. Thus, the shift to marine life also might have affected sexual dimorphism. Our measurements of 419 preserved specimens of six species of aipysurine snakes (genera Emydocephalus and Aipysurus) revealed sexual dimorphism in mean adult snout-vent length (SVL), body width relative to SVL, lengths and widths of heads and tails relative to SVL, and eye diameter relative to head length. Females averaged larger than males in all taxa, and generally were wider-bodied with shorter and wider tails and smaller eyes. For other traits, sexual dimorphism varied among species: for example, relative head length ranged from male-biased to female-biased, and head shape (width relative to length) was highly dimorphic only in A. laevis. The transition to marine life may have eliminated male-male combat (reducing selection for large males) and favoured visual rather than pheromone-based mate-searching (favouring larger eyes in males). Variation in head-size dimorphism may reflect intersexual niche partitioning, with different taxa following different trajectories. Repeated evolutionary transitions from terrestrial to aquatic life in snakes provide a powerful opportunity to explore selective forces on sexually dimorphic traits.

The sex life aquatic: sexually dimorphic scale mechanoreceptors and tactile courtship in a sea snake Emydocephalus annulatus (Elapidae: Hydrophiinae)

Evolutionary transitions from terrestrial to aquatic habitats involve major selective shifts in animal signalling systems. Entirely marine snakes face two challenges during underwater social interactions: (1) finding mates when pheromones are diffused by water currents; and, once a mate is located, (2) maintaining contact and co-ordinating mating when tactile cues are diminished by buoyancy force. We explore the potential tactile roles of scale protuberances in the mating of turtle-headed sea snakes [Emydocephalus annulatus (Hydrophiinae)] by investigating sexual dimorphism in museum specimens (N = 59). In addition to the previously noted rostral spine on the snout, we found that mature males have enlarged structures located on the chin (genial knobs) and near the cloaca (anal knobs). Ultrastructural data indicates that the rostral spine is comprised of thickened epidermal and dermal layers, similar to rugosities on the body, and likely provide stimulation to the female during prodding by the male. In contrast, the genial and anal knobs have dermally derived central cells indicative of enlarged scale mechanoreceptors (i.e. sensilla). We suggest that these mechanoreceptors are critical to mating success: genial knobs may help amorous males orient to the direction of female motion; whereas, and anal knobs likely give somatosensory feedback for cloacal alignment

Confronting taxonomic vandalism in biology: conscientious community self-organization can preserve nomenclatural stability

Self-published taxon descriptions, bereft of a basis of evidence, are a long-standing problem in taxonomy. The problem derives in part from the Principle of Priority in the International Code of Zoological Nomenclature, which forces the use of the oldest available nomen irrespective of scientific merit. This provides a route to ‘immortality’ for unscrupulous individuals through the mass-naming of taxa without scientific basis, a phenomenon referred to as taxonomic vandalism. Following a flood of unscientific taxon namings, in 2013 a group of concerned herpetologists organized a widely supported, community-based campaign to treat these nomina as lying outside the permanent scientific record, and to ignore and overwrite them as appropriate. Here, we review the impact of these proposals over the past 8 years. We identified 59 instances of unscientific names being set aside and overwritten with science-based names (here termed aspidonyms), and 1087 uses of these aspidonyms, compared to one instance of preference for the overwritten names. This shows that when there is widespread consultation and agreement across affected research communities, setting aside certain provisions of the Code can constitute an effective last resort defence against taxonomic vandalism and enhance the universality and stability of the scientific nomenclature.