New osteological and morphological data of four species ofAphaniops(Teleostei;Aphaniidae)

Aphaniops dispar, widespread around the Arabian Peninsula, was recently separated in four species (A. dispar,A. hormuzensis,A. kruppi,A. stoliczkanus) by molecular results and colour patterns, but the morphological differences are small and call for more studies. Here we report differences in skeleton and median fin osteology of these species. In addition, we introduce the term 'modified caudal vertebra' to describe caudal vertebrae that are not directly associated with caudal ray support but are visibly modified from a 'usual' caudal vertebra.Aphaniops hormuzensis, an endemic species to southern Iran, has a significantly higher number of modified caudal vertebrae compared to the more widespreadA. stoliczkanusandA. dispar, and also toA. kruppi. This is a surprising result as the caudal skeleton and related structures of the posterior caudal vertebral column have yielded successful results in separating between families or genera, but there are only a few studies that have examined these structures for their role in species diagnosis. Our study also highlights that state-of-the-art methods in X-raying and improved staining procedures assist in the discrimination of superficially similar species

The underestimated giants: operant conditioning, visual discrimination and long-term memory in giant tortoises

Relatively little is known about cognition in turtles, and most studies have focused on aquatic animals. Almost nothing is known about the giant land tortoises. These are visual animals that travel large distances in the wild, interact with each other and with their environment, and live extremely long lives. Here, we show that Galapagos and Seychelle tortoises, housed in a zoo environment, readily underwent operant conditioning and we provide evidence that they learned faster when trained in the presence of a group rather than individually. The animals readily learned to distinguish colors in a two-choice discrimination task. However, since each animal was assigned its own individual colour for this task, the presence of the group had no obvious effect on the speed of learning. When tested 95 days after the initial training, all animals remembered the operant task. When tested in the discrimination task, most animals relearned the task up to three times faster than naive animals. Remarkably, animals that were tested 9 years after the initial training still retained the operant conditioning. As animals remembered the operant task, but needed to relearn the discrimination task constitutes the first evidence for a differentiation between implicit and explicit memory in tortoises. Our study is a first step towards a wider appreciation of the cognitive abilities of these unique animals

Sexual dimorphism in postcloacal scales in the northern caiman lizard (Dracaena guianensis)

Morphological differences between males and females are common among reptiles. A particularly interesting sexually dimorphic feature whose function is largely unknown is the number and pattern of specific scales. Several lizard species possess an arrangement of centered scales near the cloacal region that differ between the sexes and can be used for sex determination. The presence of postcloacal buttons, sexually dimorphic postcloacal scales on both sides of the body, is an exclusive trait in the subfamily Tupinambinae and is only poorly documented. Here, we investigate postcloacal scales in northern caiman lizards (Dracaena guianensis) housed at the Vienna Zoo. For a period of two years, we documented scale patterns and performed morphometric measurements of individuals of different age classes. Caiman lizards were CT scanned to confirm the sexes. Males exhibit three raised postcloacal scales in a row behind the left and right leg, while females possess one or two large scales surrounded by several smaller scales. The study provides the first evidence that these scales can function as a reliable trait to distinguish the sexes regardless of age or reproductive status. The sexually dimorphic bilateral scale pattern is present immediately after hatching and does not change during development. Scales only increase in thickness and length during growth. We further demonstrate that sexual size dimorphism (SSD) exists in juveniles during ontogenetic development. Juvenile females had a larger SVL, body length, tail length and higher weight compared to juvenile males. This SSD could not be confirmed in adults, and sex determination based on SSD seems unreliable

Emergence of novel cephalopod gene regulation and expression through large-scale genome reorganization

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schmidbaur, H., Kawaguchi, A., Clarence, T., Fu, X., Hoang, O. P., Zimmermann, B., Ritschard, E. A., Weissenbacher, A., Foster, J. S., Nyholm, S., Bates, P. A., Albertin, C. B., Tanaka, E., & Simakov, O. Emergence of novel cephalopod gene regulation and expression through large-scale genome reorganization. Nature Communications, 13(1), (2022): 2172, https://doi.org/10.1038/s41467-022-29694-7.Coleoid cephalopods (squid, cuttlefish, octopus) have the largest nervous system among invertebrates that together with many lineage-specific morphological traits enables complex behaviors. The genomic basis underlying these innovations remains unknown. Using comparative and functional genomics in the model squid Euprymna scolopes, we reveal the unique genomic, topological, and regulatory organization of cephalopod genomes. We show that coleoid cephalopod genomes have been extensively restructured compared to other animals, leading to the emergence of hundreds of tightly linked and evolutionary unique gene clusters (microsyntenies). Such novel microsyntenies correspond to topological compartments with a distinct regulatory structure and contribute to complex expression patterns. In particular, we identify a set of microsyntenies associated with cephalopod innovations (MACIs) broadly enriched in cephalopod nervous system expression. We posit that the emergence of MACIs was instrumental to cephalopod nervous system evolution and propose that microsyntenic profiling will be central to understanding cephalopod innovations.H.S., O.P.H., E.R., and O.S. were supported by the Austrian Science Fund (FWF) grant P30686-B29. O.S. was supported by Whitman Center Early Career Fellowship (Frank R. Lillie Quasi-Endowment Fund, L. & A. Colwin Summer Research Fellowship, Bell Research Award in Tissue Engineering). H.S. was supported by the short-term grant abroad (KWA) of the University of Vienna. H.S. and O.S. were supported by the University of Chicago/Vienna Strategic Partnership Programme Mobility Grant. A.K. was supported by the JSPS Postdoctoral Fellowship for Overseas Researchers program from Japan. C.B.A. was supported by the Hibbitt Early Career Fellowship. Eggs and paralarvae of E. scolopes were generated in part by support by the NASA Space Biology 80NSSC18K1465 awarded to J.S.F. S.V.N. was supported by the National Science Foundation IOS-1557914. This work was supported by the Francis Crick Institute, which receives its core funding from Cancer Research UK (FC0001003), the UK Medical Research Council (FC001003), and the Wellcome Trust (FC001003)

Biomechanics and hydrodynamics of prey capture in the Chinese giant salamander reveal a high-performance jaw-powered suction feeding mechanism

During the evolutionary transition from fish to tetrapods, a shift from uni- to bidirectional suction feeding systems followed a reduction in the gill apparatus. Such a shift can still be observed during metamorphosis of salamanders, although many adult salamanders retain their aquatic lifestyle and feed by high-performance suction.Unfortunately, little is known about the interplay between jaws and hyobranchial motions to generate bidirectional suction flows. Here,we study the cranial morphology, aswell as kinematic and hydrodynamic aspects related to prey capture in the Chinese giant salamander (Andrias davidianus). Compared with fish and previously studied amphibians, A. davidianus uses an alternative suction mechanismthat mainly relies on accelerating water by separating the ‘plates’ formed by the long and broad upper and lower jaw surfaces. Computational fluid dynamics simulations, based on three-dimensional morphology and kinematical data from high-speed videos, indicate that the viscerocranial elements mainly serve to accommodate the water that was given a sufficient anterior-to-posterior impulse beforehand by powerful jawseparation.We hypothesize that this modifiedway of generating suction is primitive for salamanders, and that this behaviour could have played an important role in the evolution of terrestrial life in vertebrates by releasing mechanical constraints on the hyobranchial system

Cephalopod-omics: emerging fields and technologies in cephalopod biology

14 pages, 1 figure.-- This is an Open Access article distributed under the terms of the Creative Commons Attribution LicenseFew animal groups can claim the level of wonder that cephalopods instill in the minds of researchers and the general public. Much of cephalopod biology, however, remains unexplored: the largest invertebrate brain, difficult husbandry conditions, and complex (meta-)genomes, among many other things, have hindered progress in addressing key questions. However, recent technological advancements in sequencing, imaging, and genetic manipulation have opened new avenues for exploring the biology of these extraordinary animals. The cephalopod molecular biology community is thus experiencing a large influx of researchers, emerging from different fields, accelerating the pace of research in this clade. In the first post-pandemic event at the Cephalopod International Advisory Council (CIAC) conference in April 2022, over 40 participants from all over the world met and discussed key challenges and perspectives for current cephalopod molecular biology and evolution. Our particular focus was on the fields of comparative and regulatory genomics, gene manipulation, single-cell transcriptomics, metagenomics, and microbial interactions. This article is a result of this joint effort, summarizing the latest insights from these emerging fields, their bottlenecks, and potential solutions. The article highlights the interdisciplinary nature of the cephalopod-omics community and provides an emphasis on continuous consolidation of efforts and collaboration in this rapidly evolving fieldPeer reviewe

The oropharyngeal morphology in the semiaquatic giant Asian pond turtle, heosemys grandis, and its evolutionary implications

The oropharynx as a functional entity plays a fundamental role in feeding. Transitions from aquatic to terrestrial lifestyles in vertebrates demanded major changes of the oropharynx for the required adaptations to a different feeding environment. Extant turtles evolved terrestrial feeding modes in three families (testudinids, emydids, geoemydids)–independently from other amniotes–and are therefore important model organisms to reconstruct morpho-functional changes behind aquatic-terrestrial transitions. In this study we hypothesized that the oropharyngeal morphology in semiaquatic turtles of the geoemydid family shows parallels to testudinids, the only purely terrestrial extant lineage. We provide an in-depth description of the oropharynx in the semiaquatic geoemydid Heosemys grandis by using a combination of micro computed tomography (micro-CT) and subsequent digital in situ 3-D reconstruction, scanning electron microscopy (SEM), and histology. We show that H. grandis has a large tongue with rough papillose surface and well-developed lingual muscles. The attachment sites of the lingual muscles on the hyolingual skeleton and their courses within the tongue are nearly identical with testudinids. The hyolingual skeleton itself is mainly cartilaginous and shows distinct–but compared to testudinids rather small–anterior extensions of the hyoid body and hypoglossum. Oral glands are well developed in H. grandis but are smaller and simpler than in testudinids. Similarly, oropharyngeal keratinization was minimal and found only in the anterior palate, regions close to the beak, and tongue tip. We conclude that H. grandis shows distinct oropharyngeal morpho-functional adaptations for a terrestrial lifestyle but still retains characters typical for aquatic forms. This makes this species an important example showing the oropharyngeal adaptations behind aquatic-terrestrial transitions in turtles

Aphanius dispar

Key to species in the <i>Aphanius dispar</i> group <p> It should be noted that more than one species seems to be involved in <i>A. dispar</i> from the Red Sea basin and only limited material was available from the different molecular groups. The identification key is based on <i>A. dispar</i> from the northern Red and Mediterranean Sea basins. Other populations from the Red Sea may not be identified using this key.</p> <p> 1a Caudal fin emarginated; body without scales......................................................... <i>A. furcatus</i></p> <p>1b Caudal fin truncate; body covered by scales................................................................. 2</p> <p> 2a Lower jaw sharply upturned, oriented about 90° to body axis.......................................... <i>A. stiassnyae</i></p> <p>2b Lower jaw gently upturned, oriented about 45° to body axis.................................................... 3</p> <p> 3a Female with a midlateral row of roundish, black spots, often with additional black spots on flank; male with a wide, black dorsal-fin margin; anal fin yellow, with or without a narrow black margin and 0–2 short black bars on middle of fin... <i>A. sirhani</i></p> <p>3b Female with a midlateral row of vertically elongated black, grey or dark-brown blotches or narrow bars; male without black dorsal-fin margin, anal fin yellow anteriorly, with 3–8 narrow black or brown bars on posterior part of fin............... 4</p> <p> 4a Male with silvery vermiculation on grey background on flank........................................ <i>A. richardsoni</i></p> <p>4b Male with dark-grey bars on silvery background or with roundish or ovoid silvery spots or blotches, sometimes with short vermiculation, on a grey, greenish or blueish background, often with spots in front of anal-fin origin and bars on caudal peduncle..................................................................................................... 5</p> <p>5a Male with 9–19 brown or grey flank bars between pectoral- and caudal-fin bases.................................... 6</p> <p>5b Male with roundish or ovoid silvery spots or blotches, sometimes with short vermiculation, on a grey, greenish or blueish background, often with spots in front of anal-fin origin and bars on caudal peduncle..................................... 7</p> <p> 6a Five branched dorsal-fin rays, ½ ray absent in all individuals examined; male with 15–19 brown bars on flank, bars as wide or narrower than interspaces; female with a narrow and long bar at caudal-fin base; 4–5 scale rows on caudal-fin base.................................................................................................... <i>A. ginaonis</i></p> <p> 6b 6½–7½branched dorsal-fin rays, several individuals have 7 rays and no ½ ray; male with 9–14 brown or grey bars on flank, bars as wide or wider than interspaces; female with a diamond-shaped or slightly vertically elongate black or dark brown blotch at caudal-fin base; 2–3 scale rows on caudal-fin base............................................. <i>A. kruppi</i></p> <p> 7a Male usually without bars on caudal peduncle; tip of dorsal fin reaching to 3 scales in front of end of hypural complex in nuptial male larger than 40 mm SL; female with a midlateral series of wide bars or irregularly shaped and set, vertically elongated, lateral blotches................................................................................. <i>A. dispar</i></p> <p> 7b Male usually with wide grey or brown bars at caudal peduncle; tip of dorsal fin reaching to end of hypural complex in nuptial males larger than 40 mm SL; female with a midlateral series of narrow bars, not much wider in upper part... <i>A. stoliczkanus</i></p>Published as part of <i>Freyhof, Jörg, Weissenbacher, Anton & Geiger, Matthias, 2017, Aphanius kruppi, a new killifish from Oman with comments on the A. dispar species group (Cyprinodontiformes: Aphaniidae), pp. 557-573 in Zootaxa 4338 (3)</i> on pages 560-561, DOI: 10.11646/zootaxa.4338.3.10, <a href="http://zenodo.org/record/1036914">http://zenodo.org/record/1036914</a&gt

FIGURE 6 in Aphanius kruppi, a new killifish from Oman with comments on the A. dispar species group (Cyprinodontiformes: Aphaniidae)

FIGURE 6. Aphanius cf. kruppi, not preserved, female, about 40 mm SL, male, about 45 mm SL; Oman: Al-Hoota. Photo by Barbara Nicca (female), Kai Borkenhagen (male)