Observations on torquaratorid acorn worms (Hemichordata, Enteropneusta) from the North Atlantic with descriptions of a new genus and three new species

Abstract

Abstract. Enteropneusts in the family Torquaratoridae were imaged using still and video cameras in the deep North Atlantic and then collected by remotely operated vehicles. From this material, we describe Yoda purpurata n. gen, n. sp., Tergivelum cinnabarinum n. sp., and Allapasus isidis n. sp. Individuals of the first two species were browsing completely exposed on the sea floor, whereas the specimen of the last species was encountered floating~1 m above the sea floor. Living specimens of Y. purpurata were 12-19 cm long and had a dark reddish-purple proboscis, collar, and genital wings (folded dorsally over the anterior region of the trunk). Members of this species were hermaphrodites (the first ever discovered in the phylum Hemichordata), with numerous separate testes and ovaries in the genital wings. Living specimens of T. cinnabarinum were 12-26 cm long and had a cinnabar-colored proboscis, collar, and back veils (arising from the anterior region of the trunk); sexes were separate, and body shape and internal morphology closely resemble those of its brown congener, T. baldwinae, from the eastern Pacific. The only specimen of A. isidis collected was a male 13 cm long and pale yellow when alive. Its body shape was proportionally shorter and broader than that of its orange congener, T. aurantiacus, from the eastern Pacific, but the internal anatomy of the two species is virtually identical.

An Externally Brooding Acorn Worm (Hemichordata, Enteropneusta, Torquaratoridae) from the Russian Arctic

“…The latter are Torquarator bullocki Holland et al 2005Holland et al (1901, Tergivelum baldwinae Holland et al, 2009 (3952 m), Allapasus aurantiacus Holland et al, 2012bHolland et al, (2994; Tergivelum cinnabarinum Priede et al, (2493, Allapasus isidis Priede et al, 2012Priede et al, (2622, and Yoda purpurata Priede et al, 2012Priede et al, (2622. Smith et al (2005), Holland et al (2005Holland et al ( , 2009Holland et al ( , 2012b, Anderson et al (2011), Osborn et al (2012), and discussed the ecology of torquaratorid enteropneusts.…”

Modern Antarctic acorn worms form tubes

“…Because of these sampling difficulties, until recently, enteropneusts were poorly known from the deep sea. Increased application of deepsea imaging has helped alleviate this problem and resulted in description of a new family of deep-sea enteropneusts, Torquaratoridae 4,5 . Further, reports of enteropneusts from the Antarctic region have been limited to brief mentions in ecological studies [6][7][8] .…”

Rediscovery and augmented description of the HMS ‘Challenger’ acorn worm (Hemichordata, Enteropneusta),Glandiceps abyssicola, in the equatorial Atlantic abyss

“…In the Romanche Trench, where the neotype was collected, the substratum has variously been described as erosional sands (Heezen & Laughton, 1963) or ooze (Cifelli, 1967), and the minimum bottom temperature was about 0.7 o C (Morozov et al, 2010). However, from what is known about other deep-sea enteropneusts (Smith et al, 2005;Holland et al, 2009Holland et al, , 2012aAnderson et al, 2011;Priede et al, 2012), G. abyssicola is very likely a deposit feeder, although nothing is yet known about how selective it might be. However, from what is known about other deep-sea enteropneusts (Smith et al, 2005;Holland et al, 2009Holland et al, , 2012aAnderson et al, 2011;Priede et al, 2012), G. abyssicola is very likely a deposit feeder, although nothing is yet known about how selective it might be.…”

“…In contrast, the relatively large (300 -1500 mm diameter) oocytes of other deep-sea enteropneusts studied to date (Holland et al, , 2009(Holland et al, , 2012aPriede et al, 2012) indicate that these species develop directly without passing through a larval stagealthough Young (1994) has pointed out that predictions about life history strategy based solely on female gamete size can sometimes be unreliable. Each ovary of the neotype contains numerous oocytes, most of which had a uniform diameter about 95 mm and were enveloped with a jelly layer.…”