Margin Of Carapace Research Articles

First record of the family Callianopsidae (Decapoda: Axiidea) and a new species of Vulcanocalliax from the Hikurangi Margin off Aotearoa New Zealand, with a key to species of Callianopsidae

IntroductionThe Aotearoa New Zealand ghost shrimp of the infraorders Axiidea and Gebiidea have never been comprehensively reviewed, with recent work uncovering a diverse regional fauna representing eight of the 14 known families.MethodsUsing standard morphological and DNA sequencing tools, the family Callianopsidae is, for the first time, recorded off New Zealand, represented by a new species of Vulcanocalliax.ResultsThe new species was found near hydrocarbon seeps on the Hikurangi Margin, on the eastern New Zealand continental slope, and is only the second species now known in this genus. The single congener, V. arutyunovi, is only known from a mud volcano in the Gulf of Cádiz, off the Iberian Peninsula. Vulcanocalliax sp. nov. was formerly reported as an unnamed host of a new endemic New Zealand rhizocephalan barnacle Parthenopea australis and is here formally described as Vulcanocalliax beervana sp. nov.DiscussionThe new species differs, e.g., in the shape of the anterior carapace margin (convexly rounded and without elevated postantennal shoulder present in V. arutyunovi), the ocular peduncle having a convex anterolateral margin (compared to a straight margin), and the uropodal exopod has a dorsomedian ridge, lacking the elevated anterior portion that is distinct in V. arutyunovi. This brings the number of described New Zealand ghost shrimp species to 18. A key to all known Callianopsidae is provided.ZOOBANKLSID urn:lsid:zoobank.org:pub:4EDE6CE1-B644-4FFB-94CA-C8725A7549DD.

Variation in defensive spines across juvenile instars of Daphnia magna

Abstract Various species of freshwater zooplankton feature defensive spines, spikes or spinules across a comparatively wide size range. Among those is Daphnia magna, which has previously been found to express an enhanced spinescence in response to the predatory tadpole shrimp Triops cancriformis. This involves an elongated tail-spine, further protruding fornices and elongated, as well as further spread spinules along its carapace margins. Of these, the predator-induced trait changes concerning the spinules of D. magna at the age of first reproduction are known. However, their morphological development throughout the juvenile instars, in comparison to the changes of the prominent tail spine during the same periods, has thus far been unclear. Our study shows that D. magna expresses spinules across all investigated juvenile instars. Furthermore, during ontogeny, the development of D. magna’s rather small spinescence traits, i.e. the dorsal and ventral mean spinule length, as well as the dorsal spinules bearing area, in response to predation pressure, differs distinctly from that of the prominent tail-spine. Thus, our study provides further insight into the connectedness of traits contributing to the overall defensively enhanced spinescence of D. magna, with possible implications for the functional benefit of the traits at certain developmental periods.

Antipredator responses of three Daphnia species within the D.longispina species complex to two invertebrate predators.

Prey communities in natural environments face a diverse array of predators with distinct hunting techniques. However, most studies have focused only on the interactions between a single prey species and one or more predators and typically only one of many induced defense traits, which limits our understanding of the broader effects of predators on prey communities. In this study, we conducted a common garden experiment using five clones each of three Daphnia species (D. cucullata, D. galeata, and D. longispina) from the D. longispina species complex to investigate the plasticity of predator-induced defenses in response to two predators in a community ecology setting. Five clones from each species were subjected to predator kairomones from two closely related invertebrate predators that are common in several European lakes, Bythotrephes longimanus or Leptodora kindtii for a duration of 10 days, and the morphological traits of body size, head size, spina size, and the presence of spinules on the ventral and dorsal carapace margins were measured. We show that among the species within this species complex there are different antipredator reactions to the invertebrate predators. The induced responses exhibited were species, trait, and predator-specific. Notably, D. galeata and D. cucullata developed distinctive helmets as defensive mechanisms, while microdefenses were induced in D. galeata and D. longispina, but not in D. cucullata. This demonstrates that the expression of micro- and macrodefenses across species was unrelated, highlighting the possible independent evolution of microstructures as defensive modules in Daphnia's antipredator strategies. This study is the first to document both micro- and macrodefensive phenotypic plasticity in three co-occurring Daphnia species within the D. longispina species complex. The differences in inducible defenses may have a substantial impact on how these three species cohabit with Bythotrephes and Leptodora.

Two new species of hairy crabs (Pilumnidae) and the first record of Crinitocinus alcocki (Borradaile, 1900) (Acidopsidae) (Crustacea: Brachyura) from Taiwan.

Two new species of pilumnid crabs, Heteropilumnus planus n. sp. and Pseudolitochira taiwang n. sp., are described from reefs in Taiwan. Heteropilumnus planus n. sp. is most similar to H. hirsutior (Lanchester, 1900) from Singapore and Japan, but can easily be distinguished by its distinctly flatter carapace, different anterolateral carapace armature, longer ambulatory legs, and male first gonopod structure. Pseudolitochira taiwang n. sp. is most similar to P. crinita Ng & Clark, 2022, from Papua New Guinea but can easily be separated by its carapace physiognomy, armature of the anterolateral carapace margin and proportionately shorter ambulatory legs. Heteropilumnus setosus (A. Milne-Edwards, 1873) is also transferred to Pseudolitochira; and compared with P. taiwang n. sp. The rarely reported acidopsid, Crinitocinus alcocki (Borradaile, 1900) is also recorded from Taiwan for the first time, substantially extending its known range northwards.

First occurrence of caryocaridids (Crustacea, Phyllocarida) in the Ordovician of North China

Although caryocaridids experienced a significant biodiversity boost during the Ordovician and spread over broad trans-equatorial areas, they have been rarely reported from Siberia, Tarim and North China. Herein, we describe a new species of caryocaridids, Soomicaris ordosensis sp. nov., from the Upper Ordovician of western Inner Mongolia, China, which represents the first report of caryocaridids from the North China craton and extends the palaeogeographical distribution of caryocaridid phyllocarids to the northwestern margin of the Palaeo-Tethys. Detailed morphological and morphometric studies show that these specimens can be ascribed to different ontogenetic stages. After close inspection, we infer that Soomicaris ordosensis sp. nov. should have experienced a long pre-adult time, with several moulting stages, during which time the posterior margin of carapace gradually extends backward to form the posterodorsal spine, and the posterior margin of carapace gradually transitions from convex, linear, and finally to a rightward-sloping sigmoid curve. The taphonomic features of caryocaridids from the Upper Ordovician in the western Inner Mongolia suggest in-situ and parautochthonous preservation. The carapaces have experienced weak phosphatic mineralization during diagenesis. The Ordovician caryocaridids were most likely stenothermic which preferred to inhabit the cool- to cold-water environments from the upper mesopelagic to the lower epipelagic zones, and showed the polar emergence phenomenon.

Two new species of the genus Galathea Fabricius, 1793 (Crustacea: Decapoda: Anomura: Galatheidae) from the Andaman Sea, India

Two new species of the galatheid squat lobster genus Galathea Fabricius, 1793 are described from the Andaman Sea, India. Galathea nicobarica sp. nov. closely resembles G. rubromaculata Miyake & Baba, 1967a, but differs in the armature of the branchial carapace margin and shape of the dactylus of the third maxilliped. Galathea tirmiziae sp. nov. is allied to G. consobrina De Man, 1902 and G. tagaro Macpherson & Robainas-Barcia, 2015, but is distinguished by the merus of the third maxilliped lacking a disto-extensor spine and the proportionally more slender merus of the second pereopod.

Pricklier with the proper predator? Predator-induced small-scale changes of spinescence in Daphnia.

Phenotypic plasticity in defensive traits is a common response of prey organisms to variable and unpredictable predation regimes and risks. Cladocerans of the genus Daphnia are keystone species in the food web of lentic freshwater bodies and are well known for their ability to express a large variety of inducible morphological defenses in response to invertebrate and vertebrate predator kairomones. The developed defenses render the daphnids less susceptible to predation. So far, primarily large‐scale morphological defenses, like helmets, crests, and tail‐spines, have been documented. However, less is known on whether the tiny spinules, rather inconspicuous traits which cover many Daphnia’s dorsal and ventral carapace margins, respond to predator kairomones, as well. For this reason, we investigated two Daphnia species (D. magna and D. longicephala) concerning their predator kairomone‐induced changes in dorsal and ventral spinules. Since these small, inconspicuous traits may only act as a defense against predatory invertebrates, with fine‐structured catching apparatuses, and not against vertebrate predators, we exposed them to both, an invertebrate (Triops cancriformis or Notontecta maculata) and a vertebrate predator (Leucaspius delineatus). Our results show that the length of these spinules as well as spinules‐covered areas vary, likely depending on the predator the prey is exposed to. We further present first indications of a Daphnia species‐specific elongation of the spinules and an increase of the spinules‐bearing areas. Although we cannot exclude that spinescence is altered because it is developmentally connected to changes in body shape in general, our results suggest that the inducible alterations to the spinule length and spinules‐covered areas disclose another level of predator‐induced changes in two common Daphnia species. The predator‐induced changes on this level together with the large‐scale and ultrastructural defensive traits may act as the overall morphological defense, adjusted to specific predator regimes in nature.

Description of a new species of emGlassella/em Campos amp; Wicksten, 1997 from a coastal lagoon, SE Gulf of California (Crustacea, Decapoda, Pinnotheridae).

A new a species of pinnotherid crab in the eastern Pacific coasts is presented. Twenty males and 21 females of small crabs were collected from burrows, presumably from ghost shrimp (Neotrypaea spp.), in sand-mud substrata from the Santa María-La Reforma coastal lagoon, SE Gulf of California. The new species was assigned to the genus Glassella because its morphological characteristics clearly match the amended diagnosis of the genus Glassella by Palacios Theil and Felder (2020) and Felder Palacios Theil (2020), including the presence of a gonopodal plate (GP) inserted in the internal part of the male pleon, similar to that described for most of the species currently grouped into the genus Glassella. The new species is similar to G. miamiensis (McDermott, 2014) from western Atlantic, but it can be distinguished from this and the rest of the species of Glassella by differences in carapace margins and ridges, male pleon outline, and the shape of the GP.

Description of a new species of deep-sea spider crab from the genus Crocydocinus Lee, Richer de Forges & Ng, 2019, from the south-eastern Arabian Sea (Crustacea: Decapoda: Majoidea: Epialtidae)

A new species of spider crab is described from two male specimens collected from the southeastern Arabian Sea. This species differs from its congeners in the absence of uograstric granule on carapace, the presence of two granules along lateral margin of carapace at branchial region, the presence of granules on P2-P4 dactyli and the constricted distal tip of the male first gonopod.

Redescription, paleogeography, and experimental paleoecology of the Silurian phyllocaridGonatocaris

AbstractGonatocaris decora(Clarke, 1901) is an unusual, highly ornamented Silurian phyllocarid from the Pittsford Shale Member of the Vernon Formation, Salina Group of New York, that has been allied withEmmelezoein the past due to the possession of an ‘optic tubercle.’ The systematic positions ofGonatocarisandEmmelezoehave been difficult to assess due to the lack of complete remains, attributions based on spurious characters, and missing and unfigured specimens. Relatively recent collections ofGonatocaris decora, along with a relocation of the original type material ofEmmelezoe, have allowed a reexamination of all relevant genera and a more robust systematic placement forG. decora. Characters of generic importance forGonatocarisinclude a greatly elongated abdomen; an acute angle of the ventral carapace margin separating distinct anteroventral and posteroventral margins from each other; and distinctive, multiscale horizontal ridge-like ornament of the carapace valves. Growth was found to be isometric. Experimental work done using a model of the scale-like ornament and multiple grain sizes of substrate indicates that cuticle ornament may have served to increase friction between the animal and a fine sand substrate, although resistance to predation is the currently favored hypothesis. BecauseGonatocarisspecies are currently known only from the eastern margin of Laurentia and northern South China, it is likely that this genus was nektonic. Accumulations of similarly sized carapaces and other disarticulated sclerites in shallow-water settings may indicate spawning events following molting en masse.

A redescription of Tenagomysis species and Gastrosaccus australis from estuarine environments (Crustacea: Mysida) in Auckland region, New Zealand

Investigation of mysid habitats in estuarine waters were conducted at 59 sites throughout Auckland region from May 2006 to January 2009. This paper provides the taxonomic descriptions of the three species, collected during this survey. Among the 59 sites mysids were collected only at 26 sites: Tenagomysis chiltoni collected from 15 sites, T . novaezealandiae from 21 sites and Gastrosaccus australis from four sites. Ontogenetic variation observed in the size of the antennal scale, and counts of lateral spines and cleft spines of telson and uropod for both T . chiltoni and T . novaezealandiae. Such apparent characteristics should not be used alone to differentiate species. It is important to use a combination of characteristics such as shape of the rostrum, anterolateral margin of the carapace, number of articulations of carpo-propodus of thoracic limbs and shape and size of the antennal scale. Several aspects of the description of T . chiltoni provided by Tattersall (1923) and Hodge (1964), do not agree with the present specimens, this is due to size variations.

A new species of the ghost shrimp genus Neocallichirus Sakai, 1988 (Decapoda: Axiidea: Callianassidae) from the southwestern Atlantic

ABSTRACTA new species of ghost shrimp, Neocallichirus pinheiroi, is described based on specimens collected in subtidal habitats of Saquaira beach, northeastern coast of Brazil. This new species resembles N. lemaitrei Manning, 1993, but differs from it primarily in having a third maxilliped propodus expanded ventrally, and in the case of males, a large subtriangular tooth on the cutting edge of the major cheliped dactylus. Diagnostic features of the new species include: (i) frontal margin of carapace with rounded lateral projections not exceeding rostrum distal margin, (ii) third maxilliped carpus with row of sclerotized setae on median internal surface, (iii) minor cheliped with cutting edge of dactylus microscopically pectinate, (iv) endopod of male second pleopod with appendices interna and masculina. This is the seventh described species of the genus Neocallichirus from the western Atlantic and the fourth report of this genus in Brazil. A key for identification of western Atlantic species belonging to the genus is provided.

Redescription and new records of a poorly known leucosiid crab,Pseudophilyra punctulata Chen Ng, 2003, and description of a new species of Pseudophilyra from Japan (Crustacea: Decapoda: Brachyura).

A poorly known leucosiid crab, Pseudophilyra punctulata Chen Ng, 2003, originally described on the basis of an immature male holotype and an immature female paratype from Singapore, is rediscovered and rediagnosed on the basis of material from Thailand, the Philippines and the Ryukyu Islands (Japan). In addition, a new species closely related to P. punctulata, P. parilis, is described and illustrated on the basis of material from Mie Prefecture, Honshu mainland of Japan. The new species is distinguished from P. punctulata by the coarser granules bordering the lateral carapace margins and the different shape of the gonopods. Pseudophilyra tridentata Miers, 1879, is also compared with P. punctulata and P. parilis n. sp. because of the close similarities in the overall morphology of the carapace and appendages, but can easily be differentiated by the smoother carapace and thoracic sternum surface, different shape of the carapace and the stouter cheliped palm. It is possible that previous records of P. tridentata outside Japan might contain more than one species.

Larval development to the first eighth zoeal stages in the deep-sea caridean shrimp Plesionika grandis Doflein, 1902 (Crustacea, Decapoda, Pandalidae).

The larvae of the deep-sea pandalid shrimp Plesionika grandis Doflein, 1902 were successfully reared in the laboratory for the first time. The larvae reached the eighth zoeal stage in 36 days, both of which are longest records for the genus. Early larval stages of P. grandis bear the general characters of pandalid shrimps and differ from the other two species of Plesionika with larval morphology known in the number of spines on the anteroventral margin of carapace, number of tubercles on antennule, endopod segmentation in antenna, and third maxilliped setation. Although members in Plesionika are often separated into species groups, members of the same species group do not necessarily have similar early larval morphology. Since the zoea VIII of P. grandis still lacks pleopods and fifth pereiopod, this shrimp likely has at least 12 zoeal stages and a larval development of 120 days.

Description of two new species of the genus Automate De Man, 1888 (Crustacea: Decapoda: Caridea) from the South China Sea.

Three species of the genus Automate De Man, 1888 are described herein, including two new species: A. anacanthopusoides sp. nov. and A. spinosa sp. nov.. Automate anacanthopusoides sp. nov. can be easily identified by the presence of a rostrum, the notch on the lower margin of the major chela, the stout minor cheliped and the cutting edge of the pollex not dentate, and by the absence of spines on the ventral margin of the propodus of the third and fourth pereiopod. Automate spinosa sp. nov. can be easily identified by the nearly straight anterior margin of the carapace, and the presence of spines on the ventral margin of the propodus of third and fourth pereiopod. A key of all species of the Automate is provided.

Functional morphology of amplexus (clasping) in spinicaudatan clam shrimps (Crustacea, Branchiopoda) and its evolution in bivalved branchiopods: A video-based analysis.

Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as "claspers," which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts ("movable finger," "large palp," "palm," "gripping area," and "small palp") have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent ("partial homology"). We studied the clasper functionality in four spinicaudatan species using video recordings and scanning electron microscopy, and compared our results with other clam shrimp groups. General mating behavior and carapace morphology was also studied. Generally, spinicaudatan and laevicaudatan claspers function similarly despite some parts being nonhomologous. We mapped clasper morphology and functionality aspects on a branchiopod phylogeny. We suggest that the claspers of the three groups were adapted from an original, simpler clasper, each for a "stronger" grip on the female's carapace margin: 1) Spinicaudata have two clasper pairs bearing an elongated apical club/gripping area with one setal type; 2); Cyclestherida have one clasper pair with clusters of molariform setae on the gripping area and at the movable finger apex; and 3) Laevicaudata have one clasper pair, but have incorporated an additional limb portion into the clasper palm and bear a diverse set of setae. J. Morphol. 278:523-546, 2017. © 2017 Wiley Periodicals, Inc.

A set of possible sensory system preserved in cuticle of Late Devonian thylacocephalan arthropods from Poland

The cuticle of concavicarids (Arthropoda: Thylacocephala) from the early Famennian (Upper Devonian) of the Holy Cross Mountains, Poland was studied with respect to its microstructural details. Investigated laminated cuticle with phosphatic/organic composition, possesses two different kinds of microstructure with assumed sensory functions. The first kind consists of circular depressions, each located in the central area of characteristic polygons forming the carapace exterior ornamentation. These depressions are interpreted as sealed during phosphatisation processes setal lumens. The second kind occurs exclusively in carapace margins. These intracuticular microstructures occur as elongated tubular structures, circular to oval in cross section, penetrating the cuticle interior but not reaching its surface. They form a thin belt with a kind of ‘sensory fields’ on the dorsum and a wider belt in the ventrocaudal part of the carapace. These belts are connected in the rostral and caudal area, forming a continuous sensory zone encompassing each valve. These structures are very similar to crustacean organule canals, and the dorsally situated ‘sensory fields’, suggest some similarity to crustacean sensory dorsal organs. This possible sensory system is the oldest of this kind found in Thylacocephala. Its morphology and presumed canal walls mineralogical composition suggests crustacean affinity of Thylacocephala.

A new dromiid crab (Crustacea, Brachyura, Dromioidea) from the Upper Eocene of Huesca (Aragón, northern Spain).

A new genus and species of brachyuran crab from the Upper Eocene (Priabonian) strata in Basa Valley (Huesca, northern Spain) assignable to the superfamily Dromioidea, Basadromia longifrons n. gen., n. sp., adds to current knowledge of the morphological diversity and geographical-stratigraphical distribution of the superfamily. The main characters of the new form, such as the orbitofrontal construction with two median teeth and an rostral tooth situated in a lower plane, two minor frontal (inner orbital) teeth, well-marked cervical and branchial grooves, general carapace outline, and the shape and distribution of dorsal regions, confirm placement in Dromioidea. Unique features, such as the four conspicuous frontal teeth, lateral margins of carapace with small, subtle spines, the reduced length of the posterior margin, disposition of dorsal grooves, and peculiar shape and distribution of the dorsal regions (mainly protogastric and epibranchial), warrants the erection of a new genus and new species. In the absence of ventral features the new taxon is tentatively assigned to the family Dromiidae after detailed comparison with both fossil and extant members.

Tachypleus syriacus (Woodward)—a sexually dimorphic Cretaceous crown limulid reveals underestimated horseshoe crab divergence times

The fossil record represents an important test to molecular divergence estimates, with known occurrences representing minimum divergence times for sister taxa. As such, accurately placing fossils in phylogenies is integral to understanding the patterns and processes that shape the tree of life. The chelicerate order Xiphosura comprises classic archetypes of morphological stasis, with the earliest known Ordovician representatives exhibiting all key morphological characteristics of the group. Molecular studies on the four extant species consistently retrieve a basal split between Limulinae and Tachypleinae, but conflict regarding the relationships of the three Asian species. Molecular divergence estimates using either no or a single fossil calibration point infer a Cretaceous or Palaeogene origin for Limulidae and a Palaeogene or Neogene origin for Tachypleinae and Tachypleus. Here, we present male and female specimens of Tachypleus syriacus (=‘Mesolimulus’ syriacus) from the Cretaceous of Lebanon, revealing an anterior scalloped carapace margin in males—a derived condition of sexual dimorphism shared with Tachypleus tridentatus. Morphological phylogenetic analysis of total group Limulidae retrieves a monophyletic Tachypleus with a minimum divergence time during the Cretaceous, while crown-group Tachypleinae and Limulidae are both present during the Triassic, showing that molecular clock analyses have significantly underestimated the divergence times for these taxa.

New Report of Two Species of Crabs, Cycloes granulosa and Pugettia vulgaris (Crustacea: Decapoda) Collected from Korea

Two species of crabs, Cycloes granulosa and Pugettia vulgaris, are described and illustrated for the first time in Korea. The former is the first species of calappoid genus Cycloes and characterized by having a minute lateral spine on the margin of carapace. The latter is a species of majoid crab and similar to P. pellucens. However, it can be distinguished by shorter rostral spines, a smaller hepatic spine, and a carapace entirely covered with short setae. In Korea the calappoid crab now includes seven species of three genera (Calappa, Mursia, and Cycloes) and the majoid genus Pugettia consists of six species.