Vicariance and convergence in Magellanic and New Zealand long-looped brachiopod clades (Pan-Brachiopoda: Terebratelloidea)

Abstract

Phylogenetic reconstructions using parsimony, maximum likelihood (ML), and Bayesian relaxed molecular clock analyses of~2850 nucleotides of nuclear-encoded small and large subunit ribosomal DNAs (SSU and LSU rDNAs) from 14 long-looped (terebratelloid) ingroup and four short-looped (terebratulidine) outgroup brachiopod taxa, together with ML analyses of~663 nucleotides of mitochondrial cytochrome oxidase subunit 1 (cox1) from 12 terebratelloid taxa, show that deep divergence separates taxa endemic to waters in the vicinity of New Zealand from those with a Magellanic distribution around South America and Antarctica. This deep divergence also separates Magellanic Terebratella dorsata from New Zealand Terebratella sanguinea, showing that they are not congeneric. Instead, they belong to separate 'Magellanic' (MAG) and 'New Zealand' (NZ) clades that first diverged about 82 Mya (95% highest posterior density, 48-120 Mya), correlating with separation between the NZ and Antarctic tectonic plates. Sequence analyses also reveal (1) that the Antarctic endemic taxa Magellania fragilis and Magellania joubini are not congeneric with Magellania venosa, suggesting that their previous placement in Aerothyris should be restored, and (2) that divergence between Antarctic and NZ species of the terebratulide Liothyrella occurred much later than plate separation, perhaps because of continuing gene flow caused by long-lived larvae. The topology of the rDNA and cox1 gene trees implies that radial ornament of the shell ('ribbing') has been gained (and/or lost) independently within the MAG and NZ clades. Radial ribs are widespread in articulate brachiopods throughout the Phanerozoic, but no comparisons of brachiopod rib morphology and morphogenesis have been published. Our comparisons of transverse shell mid-sections in the scanning electron microscope reveal no obvious evidence of differences in morphology between independently gained ribs. We also consider several ways in which ribs may affect fitness, including effects on hydrodynamics. Only scanty and inconclusive evidence is available, but we suggest that effects (if any) are likely to be of small magnitude; adaptive value of brachiopod shell ribs remains to be demonstrated.

Atlas of Antarctic and sub-Antarctic Brachiopoda

“…Latitude 55°17.5'S, longitude 66°00'W, at 205--207 meters, off the southeast end of Tierra del Fuego, Argentina." Depth range: 95 --947 m. References: Cohen et al (2011), Cooper (1973a, Foster (1989, see below *), Richardson (1997), .…”

“…[South Georgia Island]. Depth range: 275 --970 m. References: Allan (1939Allan ( , 1940a, Cohen et al (2011), Foster (1989, see below *), Martens & Pfeffer (1886), , Zezina & Pakhnevich (1998. * Foster (1989) pointed out that "A better understanding of this species is particularly vital in order to adequately evaluate a number of somewhat similar species that occur in the same area that may be variants of Magellania venosa.…”

“…notorcadensis Jackson, 1912Liothyrina antarctica: Joubin (1914 ?Liothyrella ovata Thomson, 1918 Liothyrella notorcadensis Thomson, 1918 Gryphus antarcticus: Dall (1921) Gryphus uva: Dall (1921) Liothyrella oblonga Cooper, 1973a Liothyrella uva georgina Foster, 1974 Liothyrella antarctica georgina Zezina 1980Liothyrella "uva": Cooper (1983 Liothyrella uva notorcadensis: Foster (1974) Liothyrella uva cancerderma Foster, 1974Liothyris uva: Zezina (1976 Liothyrella georgina: Cooper (1982) Liothyrella fosteri Cooper, 1982 Liothyrella expansa Cooper, 1982Liothyrella notocadensis: Cooper (1982 Type locality: "in sinu Tehuantepec", "found by Captain Dare, attached to a sea--vorn bivalve, at a depth of 10--12fathoms" [18--22 m]. Depth range: 0 --2273 m. References: Alexander (1990), Barnes & Clarke (1995), Blochmann (1906Blochmann ( , 1908, Bowden et al (2006), Broderip (1833), Came et al (2014), Cohen et al (1998), Cohen et al (2011), Cooper (1973a, Dall (1908Dall ( , 1921, Davidson (1880Davidson ( , 1886Davidson ( --1888, Eichler (1911), Fischer & OEhlert (1892), Foster (1969Foster ( , 1974Foster ( , 1989, Harper & Peck (2003), Jackson (1912Jackson ( , 1918, …”

“…venosa: Levy (1961) Magellania? venosa: Cooper (1981 Type locality: "the country unkown" (Solander, 1786); "Falkland's Islands" Depth range: 2 -3510 m. References: Álvarez (2017), Cohen et al (2011), Dall (1921, Davidson (1886), , Fischer & OEhlert (1892), Försterra et al (2008), Foster (1969, 1989, Jackson (1912), Jackson et al (2015), Richardson (1997), Roux & Bremec (1996), Solander (1786.…”

“…Genus Syntomaria Cooper, 1982 [Type species= Syntomaria curiosa Cooper, 1982 (p. 20 Cohen et al (2011), Cooper (1973a, Cotton (1937), Dall (1873Dall ( , 1921, Davidson (1886), Eichler (1911), Fischer & OEhlert (1892), Foster (1969Foster ( , 1974Foster ( , 1989, Gmelin (1790), Gould (1950), d'Hondt (1976, 1977, Jackson (1912), Richardson (1997), Roux & Bremec (1996), Cooper (1982), Dall (1921), Fischer & OEhlert (1892), Foster (1969Foster ( , 1989, Helmcke (1939a), Lüter & Sieben (2005). Note: Helmcke (1939b, p. 240) mentioned that the diagnoses of the new species would follow later in a revision of the genus.…”