A new deep-sea hot vent stalked barnacle from the Mariana Trough with notes on the feeding ecology of Vulcanolepas

Abstract

A new species of deep-sea neolepadid stalked barnacle, Vulcanolepas verenaesp. nov., is described from Hafa Adai hydrothermal vent field in the Mariana back-arc basin, northwest Pacific. Vulcanolepas verenaesp. nov. is differentiated from other described species in the family morphologically by a mandible with a very small first tooth and small, non-protruding peduncular scales. Its gross external morphology exhibits a range of plasticity, similar to those previously reported from other neolepadid stalked barnacles. This is the first report of the genus Vulcanolepas in the northern hemisphere, and we discuss the phylogeography of Neolepadidae with a phylogenetic reconstruction based on the cytochrome c oxidase subunit I gene. We also discuss the relationship between key morphological characteristics and the feeding habits in the family, showing that, a number of Vulcanolepas species including Vulcanolepas verenaesp. nov. are specialized in culturing filamentous bacteria on their cirri.

Contrasted phylogeographic patterns of hydrothermal vent gastropods along South West Pacific: Woodlark Basin, a possible contact zone and/or stepping-stone

“…oshaeai in the Kermadec Volcanic Arc, and V . verenae in the Mariana Trough [ 35 , 77 – 79 ]. On the contrary, the non-hydrothermal deep-water stalked barnacle Scalpellum stearnsii forms a complex of 4 cryptic species with one species present throughout the South West Pacific, from Papua New Guinea to Fiji [ 73 ].…”

“…Considering the large geographic gap between the South West and North West regions of the Pacific, the link between the Okinawa Trough and the Mariana Trough with the Manus Basin implies the occurrence of yet undiscovered sites that could act as stepping-stones, throughout the Philippine Arc for instance. In comparison, analysis of the distribution of hydrothermal and non-hydrothermal deep-sea barnacles showed distinct distributions of closely related species between the northern and southern West Pacific [ 73 , 79 ].…”

“…Such variability in the distribution patterns of closely related species were also reported in other groups of benthic organisms such as the deep-sea stalked barnacles in the West Pacific. For instance, the genera vent neolepadid barnacles Vulcanolepas/Leucolepas display high species diversity with one species per basin: V. buckeridgei in the Lau Basin, V. fijensis in the North Fiji Basin, a new undescribed Vulcanolepas species in the Woodlark Basin, Leucolepas longa in the Manus Basin, V. oshaeai in the Kermadec Volcanic Arc, and V. verenae in the Mariana Trough [35,[77][78][79]. On the contrary, the non-hydrothermal deep-water stalked barnacle Scalpellum stearnsii forms a complex of 4 cryptic species with one species present throughout the South West Pacific, from Papua New Guinea to Fiji [73].…”

Phylogeny and adaptative evolution to chemosynthetic habitat in barnacle (Cirripedia: Thoracica) revealed by mitogenomes

“…No studies have specifically discussed the morphological or physiological adaptations of chemosynthetic barnacles for surviving in extreme environments, but Yorisue et al (2013) showed potential strategies of larval development to settle down in proper habitats developed by chemosynthetic barnacles. In comparison with their deep-sea or shallow-water relatives, chemosynthetic barnacles have a relatively larger number of setae on the intermediate segments of the posterior three cirri (i.e., generally more than six pairs vs. less than six pairs), and a higher ratio of setal length to the width of the segment where the setae are rooted (generally 2.8-14.1 vs. mostly 2.0-3.5) (primary data summarized from Yamaguchi and Newman, 1990;Buckeridge, 1998;Newman, 2000;Southward & Jones, 2003;Buckeridge et al, 2013;Watanabe et al, 2021). We speculate that these features represent morphological adaptations of chemosynthetic barnacles, as the dense and long setae would enhance the volume of water currents flowing into the mantle cavity when their cirri are beating for respiration and feeding.…”

“…Buckeridge et al (2013) have shown that the powerful morphological plasticity of Vulcanolepas scotiaensis was triggered by microenvironmental variation in chemosynthetic habitats. Several chemosynthetic barnacle species, such as V. osheai, V. buckeridgei and V. verenae, had developed ectosymbioses with sulfur-oxidizing bacteria for feeding (Southward & Newman, 1998;Watanabe et al, 2021). Furthermore, all barnacle somatotypes (e.g, sessile, stalked and asymmetric) were developed in chemosynthetic habitats.…”