Ingo Burghardt

Thermal stress response in a dinoflagellate-bearing nudibranch and the octocoral on which it feeds

Abstract In this study, we examined two non-scleractinian taxa, the rare nudibranch Phyllodesmium lizardensis and Bayerxenia sp., the octocoral on which the nudibranch lives and feeds, to investigate the effect of experimental heat stress on their symbioses with Symbiodinium. Bleaching has not been studied in nudibranchs. Bayerxenia sp. belongs to the alcyonacea family Xeniidae, members of which are known to be heat sensitive, but the genus has never been subject to heat stress experiments or bleaching observations. While qPCR did not reveal any changes to the symbiont community composition, the two host species responded differently to increased temperature. There were changes in the relative proportion of tissue types in Bayerxenia sp., but these were not attributable to the temperature treatment. Bayerxenia sp. exhibited no changes in cellular structure (apoptosis or cell necrosis), or symbiont functioning, cell size, density, or cladal community structure. On the other hand, the host, P. lizardensis, experienced tissue loss and symbiont densities decreased significantly with the majority of the remaining symbiont cells significantly degenerated after the heat stress. This decrease did not influence symbiont community composition, symbiont cell size, or photosynthetic efficiency. While the bleaching process in nudibranchs was demonstrated for the first time, the physiological and molecular pathways leading to this response still require attention.

Rhagada revisited: on the taxonomy of species from the Kimberley and Dampierland, Western Australia (Pulmonata, Camaenidae)

The genus Rhagada is the second most diverse camaenid genus in Australia. We examined anatomical and mitochondrial characters of previously unidentified material from the Kimberley that was earmarked to potentially represent new species in recently published molecular phylogenetic studies. Our comparisons revealed that specimens from Gibbings Island (‘R. sp. Gibbings’) were morphologically and genetically most similar to Rhagada cygna from the Dampier Peninsula. Hence, ‘R. sp. Gibbings’ is considered to be identical to R. cygna. In addition, we found that R. cygna as so delimited is not clearly distinguished from the second species on the Dampier Peninsula, Rhagada bulgana. Both species differ rather subtly in anatomical and mitochondrial characters, indicating their close relationships and potentially incomplete evolutionary differentiation. Furthermore, we describe two new species based on comparative morphology and mitochondrial sequences: Rhagada worora n. sp. from the Prince Regent Reserve in the Kimberley and Rhagada karajarri n. sp. from Dampierland. The present study confirms that species in Rhagada are best identified by means of both morphological and molecular data. http://zoobank.org/urn:lsid:zoobank.org:pub:556E1866-6F9E-4CC0-8ACF-CD56E929501F

Cryptic diversity in a widespread land snail: revision of the genus Xanthomelon Martens, 1860 from the Australian Monsoon Tropics (Pulmonata, Camaenidae)

The camaenid genus Xanthomelon is widely distributed throughout the Australian Monsoon Tropics and eastern Queensland, with nine species currently being recognised in Australia based exclusively on shell features. Due to the combination of poor taxonomic descriptions and considerable variation in shell characters, considerable confusion surrounds the number of species in the Northern Territory (NT), their key characteristics and distributions. To uncover the full taxonomic diversity of Xanthomelon in the NT, we employed molecular phylogenetics and comparative studies of morphology/anatomy. Based on the patterns of mitochondrial differentiation as well as comparative shell and penial anatomy, we demonstrate that previous studies failed to correctly delineate species. We recognise five species in the NT, of which two (X. darwinense n. sp. and X. arnhemense n. sp.) are newly described. These species have distributions that range from narrowly endemic to most widely distributed throughout most of the Australian Monsoon Tropics. The ranges of multiple species overlap extensively with each other, which is a rather unusual phenomenon amongst the Australian Camaenidae.

Embryonic development of the solar-powered nudibranch Phyllodesmium lizardensis (Gastropoda: Nudibranchia)

ABSTRACT In this pilot study we investigated the early embryonic development of the recently described solar-powered nudibranch species Phyllodesmium lizardensis. In previous studies P. lizardensis has been used as a model system to study the symbiosis between nudibranchs and their symbiotic dinoflagellates Symbiodinium, but the transmission mode of symbionts in the life cycle of this species remained unknown. Embryonic development in P. lizardensis was similar to related nudibranch taxa. Specimens laid clear gelatinous egg masses filled with relatively small egg capsules (81.25 ± 3.78 µm, n = 11). Zygotes developed into planktotrophic veliger larvae that hatched after about 85 hours. No Symbiodinium cells could be detected by means of light microscopy at any developmental stage in zygotes or unhatched veliger larvae. Vertical transmission of symbionts is therefore unlikely; the timing of Symbiodinium acquisition by this species remains unknown.

Southern high latitude squat lobsters II: description of Uroptychus macquariae sp. nov. from Macquarie Ridge

Squat lobsters have only recently been recorded from the Macquarie Ridge, which extends south between New Zealand and Antarctica. Among these, Uroptychus insignis (Henderson, 1885) was recorded for the first time outside the western Indian Ocean, exhibiting only subtle morphological differences. Reexamination of the Macquarie Ridge and Indian Ocean specimens attributed to U. insignis using morphological and molecular data revealed the Macquarie Ridge form to represent a separate species. Subtle but consistent morphological differences are evident and partial CO1 sequence data indicates that the specimens collected on Macquarie Ridge differ from those collected in the Indian Ocean by more than 7%. The Macquarie Ridge species is described herein as Uroptychus macquariae n.sp. Subtle morphological differences between the new species and U. insignis are discussed.

The Enidae of Timor (Stylommatophora: Orthurethra)

ABSTRACT The systematic classification of the Enidae of Timor is reviewed by means of comparative morphology and molecular phylogenetics using recently collected land snail samples from Timor-Leste (‘East Timor’). Features of the renal and genital anatomy as well as analyses of nuclear 28S rRNA sequences confirm the placement of the species in the Enidae. Generic combinations employed by earlier authors are discussed. The name Coccoderma Möllendorff, 1901 used for enids from the Indo-Australian Archipelago is pre-occupied by Coccoderma Zittel, 1887 and therefore not available. The assignment of species from Timor to Pseudonapaeus Westerlund, 1887, which is otherwise known from central Asia, is also rejected. Instead, the Enidae from Timor are here affiliated with Apoecus Kobelt, 1902, a name originally introduced for the Papuan species Buliminus colonus Möllendorff, 1895. While Apoecus samples from Timor-Leste form three distinct mitochondrial clades, only two groups can be reliably distinguished by their morphology. One of these groups represents the previously named species Apoecus apertus (Martens, 1863). This species is found throughout lowland Timor occurring at altitudes of up to 600 m. The second species has been found in the Ramelau Mountains at altitudes above 1300 m, and is described as Apoecus ramelauensis n. sp. http://zoobank.org/urn:lsid:zoobank.org:pub:3A8781B6-6EAC-4C58-8DB3-63741B03B43C