NEWSLETTER ISSN 1834-4259 NO. 149 JANUARY 2014 Sinistrality in the gastropod Zemira australis (Sowerby, 1833) (Pseudolividae) from the NSW south coast Simon Grove and Don Hird, Tasmanian Museum and Art Gallery Hobart, Tasmania Email: [email protected] With a few notable exceptions, chirality (or munities in the South East Fisheries between south- ‘handedness’) in gastropods is generally fixed: all ern New South Wales, eastern Victoria and north- members of a given species coil either dextrally (the eastern Tasmania (CSIRO, 1993). The sample in usual arrangement) or sinistrally. Despite this, rare question was collected on 03/09/1993, and came examples of the ‘wrong’ chirality are now known from east of Disaster Bay, NSW (Station 136), in 72 among a wide range of species. To this select club, –67 m of water at latitude 37°17.7´S, longitude 150° we now add the ‘false-olive’ Zemira australis 03.8´E. (Sowerby, 1833). We checked other available samples from the The genus Zemira is endemic to eastern same survey. Four others, from off Disaster Bay Australia; indeed the two species in the genus are and Bermagui in NSW and from off Point Hicks in Australia’s only representatives of the small but geo- Victoria, produced a total of another 11 Zemira graphically widespread neogastropod family Pseu- specimens; all were from waters 24–32 m deep and dolividae. Zemira australis occurs in the shallow sub- all had been live-caught apart from the five from tidal down to a depth of about 150 m, and can be Bermagui, whose shells were occupied by hermit- found from near Bicheno in north-eastern Tasma- crabs. All were dextral. nia, through eastern Bass Strait, along the coast of (Continued on page 3) New South Wales as far north as Fraser Island, Queensland. According to Des Beechey’s Seashells of The eight Zemira australis specimens, two of them sinistral, NSW website (http://seashellsofnsw.org.au), the extracted from a 1993 benthic sled sample from east of Disas- ranges of Z. australis and the second species in the ter Bay, NSW and now held at TMAG. Shell lengths range genus, Z. bodalla, overlap near Tweed Heads, with Z. from 22 to 29 mm. Photo: S. Grove. bodalla extending further north in Queensland to about Swain Reefs and tending to live in deeper waters (150–350 m). While processing and curat- ing material recently from a series of benthic sled samples from the Tasman Sea and eastern Bass Strait, we came across two sinistral speci- mens and six dextral specimens of Z. australis. All appeared to have been live-caught, though some lacked their operculum and their shells bore various encrustations. The samples had been col- lected in 1993, as part of a survey investigating the demersal fish com- 1 Society information President Rachel Przeslawski Membership fees 2014 Vice President Kirsten Benkendorff Includes Molluscan Research (published four times per Treasurer Don Colgan year) the MSA Newsletter and discounted registra- Secretary Carmel McDougall tion at the Molluscs 2015 conference. Membership Secretary Kathleen Hayes Public Relations Officer Caitlin Woods Ordinary members (Aust., Asia, w. Pacific) $A70 Journal Editor Winston Ponder Ordinary members (rest of the world) $A100 Newsletter Editors Mandy Reid Extra family member $A5 Jonathan Parkyn Affiliate organisation $A100 Website Administrator Shane Penny Student member/concession $A45 Council Members Simon Hills Jonathan Parkyn Membership fees can be paid (preferably) via the Platon Vafiadis Society’s website. All enquiries and orders should be sent to the Send subscriptions via mail to: Malacological Society Secretary, Carmel McDougall, at of Australasia, c/o Kathleen Hayes, 8 Hordern Rd, [email protected] Mt Evelyn, VIC 3796. Newsletter Victorian branch Editors: Mandy Reid, Malacology Department, Secretary Michael Lyons, 19 Banksia Street, Black- Australian Museum, 6 College St, Sydney, NSW burn, VIC 3130. Phone (03) 9894 1526 or Email: 2010. Phone (02) 9320 6412 (W), [email protected]. Meetings at the Email: [email protected] and Melbourne Camera Club, cnr Dorcas and Farrars Jonathan Parkyn, Streets, South Melbourne, on the third Monday of Email: [email protected] each month. No meeting in January, July or Decem- ber. Deadline for articles for the next issue of the News- letter: 21 March 2014. This publication is not deemed to be valid for taxonomic purposes (See article 8.2 in the International Code of Zoological Nomenclature 4th Edition.) MSA website http://www.malsocaus.org 2 (Continued from page 1) We then asked colleagues in other Australian muse- Intriguingly, we have not been able to unearth any ums to check their Zemira holdings (Z. australis and/ other instances of sinistrality in members of the fam- or Z. bodalla) and to let us know whether any of their ily Pseudolividae. However, the phenomenon occurs specimens were sinistral. The response was gratify- in other neogastropod families. Indeed there is some ingly rapid, but disappointing in that no further sin- suggestion that it occurs more in neogastropods than istral specimens came to light. Winston Ponder in other gastropod clades; of the 102 reverse-coiled (AM) reported 96 dry and 35 wet lots of Z. australis, gastropod species amassed by Florida collector Har- and 16 dry lots of Z. bodalla, many with multiple old G. Lee, all but 11 are neogastropods (see http:// specimens; Richard Willan (MAGNT) reported 15 www.jaxshells.org/reverse.htm). Why this might be shells in six dry lots (one lot of two shells comprised so is not clear; the separate sexes and copulatory Z. bodalla); John Healy (QM) reported six Z. australis mating systems of neogastropods, including false- and six Z. bodalla; Julian Finn (MV) reported 6o lots, olives (Ponder and Darragh, 1975) ought to militate many with multiple specimens (two of these Z. bodal- against the propagation of reverse-coiling, since chi- la); and Andrea Crowther (SAM) reported six lots of rality has a bearing on the orientation of the genita- 32 specimens, all Z. australis. Lisa Kirkendale (WAM) lia. This means that successful interchiral matings reported no Zemira holdings. In total, these reports (between dextral and sinistral individuals) seem high- account for well over 200 specimens, and perhaps ly improbable, particularly for low-spired species that closer to 300. engage in ‘face-to-face’ mating (Schilthuizen and Our findings beg the question as to why a Davison, 2005), as would be the case for many neo- single sampling event was able to produce not one gastropods. This copulatory barrier implies that the but two sinistral specimens, contrasting with the proportion of sinistral individuals in an otherwise complete absence of sinistrality amongst all the oth- dextral species should seldom rise to the equilibrium er samples held in museum collections around Aus- that would be predicted by population genetics tralia. It is unlikely that the cause of sinistrality was a alone, even if there were no other selection pressure developmental hiccup — after all, why would this disfavouring reverse-coiled individuals. happen twice, and in the same location at the same However, chance may at times dictate that time? More likely, it was the result of past mutation. two sinistral individuals do indeed meet and mate. In It is believed that while several genes may be such rare circumstances, there would be no copula- involved in orchestrating chirality, a mutation in one tory barrier, and the proportion of sinistrality in the of these may cause an individual’s chirality to ‘flip’. local population could indeed climb. This must be a Typically, the standard (and usually dominant) allele rare occurrence, since there are very few document- codes for the species’ ‘right’ chirality while a mutant ed cases of established sinistral populations of other- version (usually recessive) codes for the ‘wrong’ chi- wise dextral neogastropod species. Valero (1972) rality (reverse coiling). Under a normal Mendelian reported finding nine live sinistral specimens of Co- system of inheritance, the reverse-coiled offspring nus ventricosus (Conidae) in close proximity to each could arise if at least one parent was itself reverse- other, near the shores of the Mediterranean at Cap coiled, or if both parents were normal but each was Benat, near Toulon in France. Also on Mediterrane- heterozygous, bearing a single copy of the recessive an shores, Donati et al. (1984) reported finding elev- allele coding for reverse coiling. But in a peculiar en sinistral specimens of Conus mediterraneus form of inheritance displayed by some pulmonate (Conidae) over a period of two days in the vicinity of gastropods, chirality is not determined by which al- Mediba, Sardinia; this find followed discovering five leles the individual itself carries, but by which alleles sinistral specimens in the same area in 1973. its mother carried; this is known as maternal delayed Our finds leave open the possibility, there- inheritance (Freeman and Lundelius, 1982). In such fore, that there is a self-sustaining population of sin- species, an individual’s chirality is decided very early istral Zemira australis in the vicinity of the point of on in its development, and is mediated by maternal origin of our two specimens. Twenty years on, per- messenger RNA or proteins acting on the as-yet un- haps it’s time someone with a boat and some sort of fertilised egg; those agents are of course the product benthic sampling device revisited the locality to try of the maternal genotype, so the phenotype of the and find out? offspring reflects her genotype rather than theirs (Schilthuizen and Davison, 2005). Postscript Of course, pondering modes of inheritance Having written this article, we heard from Lynton cannot solve the question as to the origin of sinistrali- Stephens that there is a sinistral specimen of Zemira ty in the sampled Zemira; at best, it only pushes the australis on display at the Griffiths Sea Shell Museum possible origin back by one generation.