Taxonomic revision of the genus Cabassous McMurtrie, 1831 (Cingulata: Chlamyphoridae), with revalidation of Cabassous squamicaudis (Lund, 1845)

Cabassous comprises armadillos lacking a full osteoderm cover in the tail, justifying its common name naked-tailed armadillos. In the only taxonomic revision of the genus, in 1980, four living species were recognized, including a polytypic taxon with two subspecies. Recent studies have questioned this classification, but a comprehensive taxonomic review is lacking. Here, we revise the taxonomy of the genus Cabassous using complementary morphological approaches and clarify the geographical limits of naked-tailed armadillo species. Based on qualitative and quantitative analyses, we recognize five living species: C. centralis, C. chacoensis, C. squamicaudis, C. unicinctus, and C. tatouay. Most of the species can be easily differentiated using external or cranial traits, except C. centralis and C. unicinctus, which share several morphological features. The scutes pattern on the cephalic shield is an important diagnostic feature in naked-tailed armadillos and can be easily applied in field studies. Cabassous squamicaudis and C. unicinctus were previously treated as subspecies but we show they have conspicuous diagnostic traits, without mixture of characters even in closer contact. Cabassous species can be classified as open-dwellers (C. chacoensis and C. squamicaudis), forest-dwellers (C. centralis and C. unicinctus), or of more generalist habits (C. tatouay). We designate a lectotype for C. unicinctus to preserve its long-term nomenclature use.

Zooid morphology and molecular phylogeny of the graptolite Rhabdopleura annulata (Hemichordata, Pterobranchia) from Heron Island, Australia

Rhabdopleura Allman, 1869 is one of the longest surviving animal genera. The five-known species are the only living Graptolithina, a group well known from their diverse Paleozoic fossil record. Here we add information on the soft-bodied zooids and molecular phylogenetics of Rhabdopleura annulata Norman, 1921, which was previously only known from its tubes. Tubes and zooids were collected from Heron Island, Queensland, Australia. Zooids have a single pair of tentaculated arms. Dark pigment granules are found throughout the body, and particularly dense in the pair of arms and the anterior lip of the cephalic shield. Colonies grow encrusted in and on coral debris. The tubes are either creeping or erect, but no stolon has been found. Inside of the coral matrix lacunae, the tube cortex formed a parchment-like wallpaper. Phylogenetic analysis based on combined 18S+16S rRNA sequences placed R. annulata as sister to the remaining rhabdopleurids, albeit with weak support. The biogeographic range of R. annulata extends from Indonesia to Tasmania, and New Zealand. Its occurrence on Heron Island does not extend this range, but highlights that rhabdopleurids may be more common, and in shallower waters, than previously appreciated, permitting further studies that may shed light on graptolite paleobiology.

Compound slides: a new technique for examining branchiopod head pores in optical microscopes

A new technique for the optimization of the taxonomic study of cephalic openings in Branchiopoda is proposed here. The study of the cephalic openings in the various taxa that constitute this clade is of great importance. This is true not only for taxonomic studies, being fundamental for species identification in the Chydoridae, but also for phylogenetic and physiological investigations. For this, currently available protocols include the use of electron microscopic analysis, using the whole specimen, or the use of optical microscopy, by removing the cephalic shield from the specimen and mounting it on slides. This work presents a simple technique for the study of cephalic openings in Branchiopoda, facilitating their study, particularly for those associated with the Chydoridae.

From swimming towards sessility in two metamorphoses – the drastic changes in structure and function of the nervous system of the bay barnacle Amphibalanus improvisus (Crustacea, Thecostraca, Cirripedia) during development

Knowledge about the development of the nervous system in cirripeds is limited, particularly with regard to the changes that take place during the two metamorphoses their larvae undergo. This study delivers the first detailed description of the development of the nervous system in a cirriped species, Amphibalanus improvisus by using immunohistochemical labeling against acetylated alpha-tubulin, and confocal laser scanning microscopy. The development of the nervous system in the naupliar stages corresponds largely to that in other crustaceans. As development progresses, the protocerebral sensory organs differentiate and the intersegmental nerves forming the complex peripheral nervous system appear, innervating the sensory structures of the cephalic shield. During metamorphosis into a cypris the lateral sides of the cephalic shield fold down into a bilateral carapace, which leads to a reorganization of the peripheral nervous system. The syncerebrum of the cypris exhibits the highest degree of complexity of all developmental stages, innervating the frontal filaments, nauplius eye, compound eyes and the antennules. During settlement, when the second metamorphosis occur, the closely associated frontal filaments and compound eyes are shed together with the cuticle of the carapace and the antennules. In adults, the syncerebral structures are reduced while the ventral nerve cord and the peripheral nervous system increase in complexity. The peripheral nervous system plays an important role in processing sensory input and also in settlement. In summary, through the larval development we observed a structural and thus also functional increase of complexity in favor of the peripheral nervous system and the ventral nerve cord.

Morphological differences between phyllosoma larvae from the western–central and eastern Pacific populations of the pronghorn spiny lobster Panulirus penicillatus

The pronghorn spiny lobster Panulirus penicillatus is known to have the widest distribution among palinurid lobster species, occurring in tropical and sub-tropical areas of the Indo-Pacific Ocean. In the Pacific Ocean, mitochondrial DNA analyses have revealed that the western–central and eastern populations are genetically isolated. We performed morphological investigations on mid- to late-stage phyllosoma larvae collected in these two areas. The larvae of the western–central population had a significantly narrower cephalic shield, shorter abdomen, and longer eyestalk than those of the eastern population. Additionally, for larvae larger than about 25-mm body length, the widest position of the cephalic shield in the western–central population was located closer to the middle of the median line of the cephalic shield than that in the eastern population. The ratio of width to length of cephalic shield and the ratio of cephalic shield width to thorax width are key traits for distinguishing between the larvae of the two populations.

The zoogeography of extant rhabdopleurid hemichordates (Pterobranchia : Graptolithina), with a new species from the Mediterranean Sea

The early origin and evolutionary radiation of graptolites (Hemichordata:Pterobranchia) is a story told almost entirely in the fossil record, but for four extant species of the genus Rhabdopleura Allman, 1869. Here we report the discovery of a fifth species, Rhabdopleura recondita, sp. nov., at a depth range of 2–70m from the Adriatic and Ionian Seas, always associated with bryozoans in coralligenous habitats. This is the first pterobranch record in Italian waters, and the second in the Mediterranean Sea. The new species is characterised by: (1) tubaria with smooth creeping tubes adherent to the inside of empty bryozoan zooecia; (2) erect outer tubes with a graptolite, fusellar-like organisation; and (3) zooids that extend from a black stolon, which is free from the creeping tube. Each of the paired feeding arms has two rows of tentacles that do not extend to the arm tip. The distal ends of the arms, the collar and the cephalic shield are replete with black granules. Phylogenetic analyses of individual and concatenated gene sequences of mitochondrial 16S rDNA and nuclear 18S rDNA support the validity of R. recondita as a new species. Finally, we discuss the global biogeographic and habitat distributions of the extant Rhabdopleura representatives. http://zoobank.org/urn:lsid:zoobank.org:pub:82C6A51E-F8F4-44AF-AD8F-16873BE80D03

A restudy of Utahcaris orion (Euarthropoda) from the Spence Shale (Middle Cambrian, Utah, USA)

Utahcaris orion Conway Morris & Robison, 1988, from the lower middle Cambrian (Series 3, Stage 5) Spence Shale Member situated in Utah, USA, is redescribed based on a restudy of the original material. Newly recognized features, including ventral lateral eyes, trunk appendages, and a bulbous cephalic shield with subtriangular extension, reinforce similarities with Sanctacaris uncata from the middle Cambrian Burgess Shale. Both are assigned to the new family, Sanctacarididae. Sanctacaridids represent the oldest chelicerates. Their ecology and that of their nearest non-chelicerate relatives indicate that Chelicerata were plesiomorphically predatory.

A new aglaspidid-like euarthropod from the lower Cambrian Emu Bay Shale of South Australia

A new euarthropod from the Emu Bay Shale (Cambrian Series 2, Stage 4) on Kangaroo Island, South Australia, is a rare component of this Konservat-Lagerstätte. The two known specimens of Eozetetes gemmelli gen. et sp. nov., in combination, depict a non-biomineralized euarthropod with a relatively short cephalic shield lacking dorsal eyes and bearing a flagelliform antenna, 18 trunk segments with broad tergopleurae and paired axial nodes/carinae, and an elongate, styliform tailspine. The new species compares most closely with taxa in the putative clade Vicissicaudata, which groups Aglaspidida, Cheloniellida and Xenopoda. A ring-like terminal tergite in E. gemmelli corresponds to the caudal tergite in cheloniellids and xenopodans. Incorporating Eozetetes into recent character sets for Cambrian euarthropods supports close affinities to either Emeraldella or to aglaspidids, but several plesiomorphic character states are inconsistent with membership in Aglaspidida sensu stricto. Eozetetes is among the earliest of various Cambrian taxa informally referred to as ‘aglaspidid-like euarthropods’.

A New Helmetiid Arthropod from the Early Cambrian Chengjiang Lagerstätte, Southwest China

A new arthropod, Haifengella corona new genus new species is described from the early Cambrian Chengjiang Lagerstätte (Series 2, Stage 3), Yunnan Province, southwest China. It is readily assignable to helmetiida based on gross morphology of the tergum. The new helmetiid is unique in having the marginal spines extending over one-third of the total body width. The weakly sclerotized tergum consists of six thoracic tergites with edge-to-edge tergite articulations. The sub-trapezoidal cephalic shield has a pair of long spines projecting from each posterolateral corner. A prehypostomal sclerite (anterior sclerite) recesses in the anterior margin of the cephalic shield, and a pair of bulges that are close to the prehypostomal sclerite in the cephalic shield are presumed to be the position of ventral eyes. Each of the thoracic tergites exhibits a pair of long spines projecting from the posterolateral corners. The semicircular pygidium carries one terminal spine and two pairs of lateral spines.

The tantulocarid genus Arcticotantalus removed from Basipodellidae into Deoterthridae (Crustacea: Maxillopoda) after the description of a new species from Greenland, with first live photographs and an overview of the class

A new species of Tantulocarida was found off the coast of Disko Island, West Greenland. The new species, Arcticotantulus kristenseni sp. nov., is exclusively found on an as yet undescribed species of Bradya Boeck, 1873 (Copepoda, Harpacticoida) caught at depths of 200 m off the coast in muddy sediments. A total of 44 individuals were found, and 38 were examined by use of LM and SEM; these represented different stages of the life cycle: tantulus larvae, developing males, parthenogenetic females, and what may be only the third record of a developing sexual female. Arcticotantulus kristenseni is tentatively placed in Deoterthridae based on the mode of formation of the male trunk sac, the pattern of ornamentation on the tergites and cephalic shield, and the number of setae on the thoracopods and caudal rami. It is suggested that the genus Arcticotantulus Kornev, Tchesunov & Rybnikov, 2004 is removed from Basipodellidae and placed in Deothertridae instead, in accordance with the mode of trunk sac development in males and the absence in the latter family of a cephalic rostrum. Various internal anatomical features were examined, including the tubular structures inside the head of the tantulus larvae. The first live photographs of any species of Tantulocarida are presented. This is also the first report on Tantulocarida from West Greenland.