The malacologicalsocietymalacological society of Japan Rre VENUS (Jap. Jour. Malac.) Vol. so, Ne. 2 (1991):130 149 = - v> - 7 . 7 Fre V a V ff V it{ s 7v rfiKcD !k!Ck . ttJEmpthts -? 6ELktaJE!ff ] i )lf'l EiF v . v ti V it{ `pt !v de"d !Ell}Fomelt B. E i>y . ij The Evolution of the Ancillinae with Special Reference to New Zea]and Tertiaryand Recent Speciesof A7nalda H. & A. Adams, 1853 Olividae: Ancillinae) (Gastropoda: B. MIcHAux (Zoelogy Department, Evolutionary Geneties Laboratory, Auckland University, Private New Zealand)* Bag, Auekland, Abstract: Amal(la numerieally the most is important genus in the subfamily Aneillinae, but the systematics and the taxonomy of the group is poorly understood. This contribution represents an atte･mpt to increase understanding of the evolution of this The study is based on group. New Zealand Tertiary and Recent members of the genus and relevant literature published since Olson's original work. on Zealand (1956) Based New species, it is proposed that the subgenus Alocospira be elevated to generic rank, and that three subgenera of Amatda be reeognised-Gracilispira, Ba･ryspira, and Spinaspira. On the basis of shell charaeteristics it is by no means certain that Gracilispira is monophyletie. Three are recognised informal groups within the subgenus Baryspira-the extinct rchusta-group for large, bieonie shells with extensively developed, tongue-shaped eallus, parietal the mucronata-group for species with rnucronate spires, and the australis-group for species with conie spires, The relationship between species these and those from other parts of the world is discussed. The disjunct distribution of Amalda and Alocospira in northern and southern hemisphere waters temperate is noted. Three hypo- theses whieh attempt to explain this distribution pattern are discussed. A dispersalist explanation is detailed and rejected. Two vieariant explana- tions are also presented. concluded Both that the disjunet distribution noted for these is best made intelligible genera by reference to the breakup of Gondwana. However, these two hypotheses differ in a number of important details.In the/ hypothesis by Kilburn proposed (1981b), Amal(la populations were carried by dispersing Gondwanic fragments and subsequently removed * Present address: Private Bay, Kaukapakapa, New Zealand NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Michaux: Evolution of Ancillinae 131 from tropical Indo-Pacific regions by competition with, and predation from, other Olividae. In the hypothesis presented in this papeT, deep water ancestral taxa were earried on Gondwanie fragments. These ancestral taxa are then hypothesized to have given rise independently to northern and southern populations. A phylogenetic test, based on the cladistie analysis of allozymic data, is proposed to tes･t these hypotheses, Introduction My primary interest is in evolution and to this end the Ancillinae is a potentially ideal group te study because they are widely distributed in both space and time, and live animals are available for study. The combination ef fossil and modern data enables evolutionary problems to be examined combining the strengths of both approaches (Michaux, 1988). In a series of papers concerning New Zealand Tertiary and Recent speeies of Amalda, a genetieal and morphological based taxonomy for this genus has been outlined (Michaux, 1987; 1989a), changes in form of a number of extant species threugh time has been earried out using multivariate statistical analyses (Michaux, 1989b), and the relationship between the geological de- velopment of the southwest Pacific and the biogeography of the region discussed (Michaux, 1989c). It is the purpose of this paper to make the first steps in extending what has been learnt about the evelution of Amalda in the New Zealand region to the genus as a whole. This task can only be tentative beeause there are still uncertainties in the taxonomy, and the systematic relationships between the various taxa that are reeognised in this genus. However, enough is known to construct a number of testable, working hypotheses whieh it is hoped will lead to a mere complete understanding of the evolution of the Ancillinae. There are three interrelated areas of study which are necessary to consider if evolution is to be made intelligible. Croizat (1964) deseribed these as Space, Time, and Form. This paper is organized around the three concepts of fbrm (taxonomy), time (fossil evidenee), and spaee (biogeography). The final section outlines three hypotheses about the evolutionary history of the group. Form Chavan (1965) was the first modern worker to attempt a broad classification of the Aneillinae. It is upon this classification that subsequent workers have built. Foremost amongst recent works are Kilburn (1981a, b). Kilburn (1981b) is an important treatment of Aneitlus, the largest tropical genus in the subfamily. Ancillinae are also found in temperate seas. These temperate species, classified in the genus Amalda, are numerically the most important grouping. Olsen Barysptra (1956), working on New Zealand Tertiary and modern (=Amalda NII-Electronic Library Service The malacologicalsocietymalacological society ofJapanof Japan 132 VENUS: VoL 50, No. 2 (1991) Table 1.Charactersand character state distribution matrixused to obtainFigure 2 Character States 123456789101112Protoconch O=bulbous 1=-pointed Parietal callus margin O=irregular 1=sigmoidal 2=:tongue 3:=other Spire height O=high 1==medium 2=:low Spire shape O =: conic 1 =T- mucronate 2 == bullet Ancillid groove O=::absent 1=present Body whorl outline O=slight infiation 1=moderate infiation 2=cylindri cal 3= taperig Aperture shape O=tear drop 1 =T- oval 2=triangular SizeGrooves O=: rnedium 1 =] small 2=', large on spire O=absent 1 == present Ridge at base of spire O=absent 1==present Cross sectional shape O=:dorso-ventral flatteni'ng 1=cylindrical Denticular projection O=absent 1=-present Character 12o 34oo 56 78OO 9 10 11 12 Gracilispira ooo1 ooOl 1 OOO 1010 O O O I SPinasPira OIOO OOeo O OOI OOOI O I I O AlocosPira OOI ol 1 OIO OO 1010 BaryPira australis-type O 100O 10 OO 1 loe100OOIoo ooooO O O I mucronata-type 100O 10 10 1 ooOlO O O I robusta-type OIO 10 10 O Ol OOOI Protoconch tion ADe ch Fig. 1.An Amalda shell illustrating the terminology used. of Chavan), recognised six subgeneric groupings. These were: Ba･rypira s. str., Gemaspira, SPinasipra, Gracilispira, Alocosptra and Pinguisptra. Ponder Both (1968) and Beu (1970) have discussed aspects of Olson's NII-Electronic Library Service The malacologicalsocietymalacological society of Japan Michaux :Evolution ef Ancillinae 133 r Amalda -. r Baryspira o fi Fig. 2. Most parsimenious cladogram for the data presented in Table 1, Analysed by PENNY algorithm CPHYLIP v3. 1), CI=O, 88. a b c d ,N･tZ...･･. .//./t.tt//.t.t/.t.ttt "'ltii'i'i'i'"i"1' ili/'/1't'/"l'/'ill'ii'/' le sp.; Fig. 3. New Zealand fossil Alocospira; a. A. hebera;b. A. nov. c. A. cuPPedia; cl. A. subhebera. Black=parietal callus; stippled==$pire callus, (1956) work. They both suggested that Olson's (1956) subgEmus PinguisptTa is an invalid taxon. This was subsequently eonfirmed by Michaux (1987) wheii a cladistic analysis of eleetrophoretic data showed that Amalda (Pinguispirth) depressa was the sister taxbn of Amatdes (Bcwysptra) australis, which together foTm a sister group te Amalda (BaTysptra) mzacTonata. A eladistic analysis of New Zealand fossil and extant Amatda has previously been carried out (Michaux, 1989). That analysis, together with stratigraphic NII-Electronic Library Service The malacologicalsocietymalacological society of Japan 134 VENUS: VoL 50, No,2(1991) evidence, suggested that Olson's (1956) subgenus Alocospira, which has existed since the Eocene, should be elevated to rank, generic and that three subgenera- Baryspira, and Gracilisptra, Spiuaspira-should be recognised within Amalda. Beu's suggestion subgenus C197e) that the Ge7nasptra should be synonymized with Barysptra is accepted because Gemmsptra is a paraphyletie taxon whieh is ancestral to Barysptra. In this reanalysis, present the relationship between the three subgenera of Amalda and Alocospira have been reassessed on a subgeneric basis. This results in a tendency to idealization and ignores detail at the speeies level. The characters and character-state distribution matrix used are given in Table 1. Fig. 1 shows a Amcrlda generalized shell illustrating the terminology used. A single most parsimonious tree was produced (using the PENNY algorithm in Felsenstein's PHYLIP paekage, version 3.1) whieh had a consistency index O.88. of This tree was rooted, using Alocospz'Ta as the outgroup, to produce the cladogram shown in Fig. 2. In this analysis Sptnasptra and Baryspz'ra! Graeilisptra are sitser taxa. A classification for New Zealand specimens, based on Michaux (1989) and Fig. 2, is as follows: Genus Aloeosptres Cossmann, 1899 Genus Amalda H. & A. Adams, 1853 Subgenus BarysptTa Fischer, 1833 robusta-group australis-group mucronata-group Subgenus GraeiZispi･rth Olson, 1956 Subgenus Sptnaspira Olson, 1956 Key for the identification of taxa: 1. Spiral grooves present ,..................Alocosptra 2. Spiral grooves absent ..,..,..........,..,....3 3. Shell cylindric-pupoid ...................,Alocosptra 4. Shel] biconic .............,........,.,....,..6 5. Shell ovate .............................,.,.8 6. Sharp apieal spine present ...............Sptnasptra 7. Apex eompletely obscured by callus .......Barysptra (robusta-group) 8. Moderate infiation