Hermit Crab Genus Research Articles

Morphological and molecular analysis of the tropical hermit crab Calcinus vachoni (Decapoda, Diogenidae) and its potential association with colonial anemone.

Calcinus is the colorful hermit crab genus belonging to the family Diogenidae and is often found in coral reefs of the tropical Indo-West Pacific region, including southern Honshu, Japan, which is the northern limit of their occurrence. In the present study, we found C. vachoni for the first time in the intertidal zone of Jeju Island-the southernmost island of South Korea. We examined their morphology and provided a diagnosis of their morphological details with illustrations. In addition, the Korean Calcinus population was genetically characterized using mtDNA cox1 sequences and by placing them into three previously reported regional haplogroups. The phylogenetic tree from maximum likelihood analysis revealed that Korean C. vachoni is assigned to the C. vachoni haplogroups exclusively, one of the three well-supported mitochondrial haplogroups with distinct geographic ranges (i.e., C. vachoni, C. aff. vachoni Cooks, and C. aff. vachoni Mascarenes). This result provides new information on the species distribution of C.vachoni, extending their geographic range further north into the southern coast of Korea. In this study, we also first report the potential association of C. vachoni with their co-occurring colonial anemone species Palythoa aff. mutuki and dead coral head of Pocillopora species based on our on-site observation and a public coral collection database of Calcinus species. However, their ecological association with co-occurring coral species is putatively assumed for now and therefore has to be validated by compelling evidence from further field observation and experimental studies (i.e., whether the presence/absence of colonial anemones affects the behavior and survival of the hermit crabs).

A new species of hermit crab of the genus Pagurus Fabricius, 1775 (Crustacea: Anomura: Paguridae) from north-western Africa

One male and two female specimens of an undescribed species of the heterogeneous hermit crab genus Pagurus Fabricius, 1775, were found during the study of the collections of the Oceanographic Institute of Cádiz, containing specimens from African and European coasts collected during the scientific cruises carried out between in years 2008-2013. The new species is named Pagurus pectinidactylus n. sp., in reference to the presence of a well-developed toothless pectinate masticatory border in the dactylus of the left cheliped, composed by a row of tightly placed bristles forming a brush-like structure. The new species is compared to morphologically similar congeners, especially those that are genetically closest. Molecular phylogenetic analyses support the morphological delimitation, with P. pectinidactylus n. sp. forming a separate clade, more closely related to a group of South African species belonging to the Pagurus anachoretus group.

A new species of the diogenid hermit crab genus Pseudopaguristes McLaughlin, 2002 from the Northern Mariana Islands, Micronesia.

The diogenid hermit crab genus Pseudopaguristes McLaughlin, 2002 is currently represented by 15 species worldwide. In this study, we describe a new species of the genus, P. flavioculus, based on a unique male holotype from off Sarigan, Northern Mariana Islands, Micronesia, at depth of 131133 m. The new species appears similar to the type species of the genus, P. janetkae McLaughlin, 2002, but the lack of conspicuous spines on the dorsal face of the right cheliped carpus, the possession of a median row of tiny spines on the dorsal face of the left cheliped carpus, and different colour pattern of the cephalic appendages and the ambulatory legs distinguish P. flavioculus n. sp. from P. janetkae. Pseudopaguristes has been differentiated from the two allied genera, Paguristes Dana, 1851 and Areopaguristes Rahayu, 2012, by the possession of eight functional pairs of gills (versus 13 pairs in Paguristes and 12 pairs in Areopaguristes), but our examination of the new species and three other congeneric species available for study clarifies that the development of arthrobranchs on the maxillipeds 3 and chelipeds is rather variable in species currently assigned to Pseudopaguristes. Careful observation of the anterior arthrobranchs is recommended to avoid misinterpretation in the counts of gill numbers.

A new species of the hermit crab genus Cancellus H. Milne Edwards, 1836 from a mesophotic deep bank in the northwestern Gulf of Mexico (Crustacea: Decapoda: Diogenidae).

Recent sampling on mesophotic deep banks in the northwestern Gulf of Mexico has produced a previously undescribed hermit crab assignable to the genus Cancellus H. Milne Edwards, 1836. Members of the genus are most often found to occupy cavities of eroded coral, siliceous sponges, porous calcareous rock fragments, algal concretions, or worm tubes as shelters. The present specimen was found loose as by-catch in a dredged rhodolith sample taken for algal life history studies. In situ, it likely occupied a cavity within one of the collected calcareous rhodoliths or small sponges in the by-catch. While our description is based on a single female specimen, the holotype is fully mature and intact, and it was solidly frozen in seawater until its coloration could be photographically documented and tissues extracted for sequencing. In comparison to the three other known western Atlantic species, the frontal rim of the carapace shield in the new species is continuous between the blunt lateral teeth as in C. ornatus Benedict, 1901 and C. viridis Mayo, 1873, and thus distinct from the subdivided front found in C. spongicola Benedict, 1901. The rim itself is somewhat flattened as in C. ornatus rather than inflated as in C. viridis. However, each of the ocular scales bears a pair of spines at the tip, as in C. viridis. The lower palms of the chelipeds, while distinctly rugose, do not have a separated patch of stridulating ridges comparable to those reported for C. spongicola. The yellow-orange to deep-orange pigmentation of the color pattern differs from fresh coloration in both C. ornatus and C. viridis, but that of C. spongicola is unknown for other than preserved specimens. Description of the single available specimen is in this case justified by the low likelihood for timely acquiring of additional samples from the type locality or adjacent habitats, most of which are deep banks warranting protection under pending habitat management changes. Our diagnosis includes GenBank accession numbers for COI sequences to facilitate future molecular phylogenetic comparisons.

Turleania rubriguttatus, a new species of pagurid hermit crab (Decapoda: Anomura: Paguroidea) from shallow water in Japan, with notes on T. senticosa (McLaughlin amp; Haig, 1996).

A new species of the pagurid hermit crab genus Turleania McLaughlin, 1997, T. rubriguttatus, is described on the basis of two specimens, including one male and one female, from shallow subtidal waters in Kochi Prefecture, Japan. The new species appears close to T. albatrossae (McLaughlin Haig, 1996), known from the Philippines, but the proximally unarmed dorsal surface of the right chela palm and the lack of a dorsomesial row of spines on the left cheliped carpus easily distinguish T. rubriguttatus n. sp. from T. albatrossae. Examination of the type material of T. similis Komai, 1999 and T. spinimanus Komai, 1999, and supplemental material from Japan, confirms that the two taxa are synonymous with T. senticosa (McLaughlin Haig, 1996), as was suggested by previous authors. Re-examination clarified that in T. senticosa the maxilliped 3 has no developed arthrobranchs, and this led the author to assess the status of T. sinensis Han, Sha An, 2016, which is also synonymised with T. senticosa.

Joecalcinus, a new hermit crab genus from the Eocene of northern Italy: the second Cenozoic representative of the extant family Calcinidae (Decapoda, Anomura)

A diminutive paguroid shield from Lower Eocene strata in the Lessini Mountains (northern Italy), recorded several years ago as Paguristes sp. (sensu Beschin et al. 2016), is here transferred to the family Calcinidae Fraaije, Van Bakel & Jagt , 2017, on the basis of the presence of an intra- gastric Y-linea. The new genus and species, Joecalcinus bolcensis, erected here constitute the second known extinct member of this family. We postulate that calcinids derived from the Annuntidiogenidae Fraaije, 2014 during the Late Cretaceous.

A new species of the hermit crab genus Diogenes Dana, 1851 (Decapoda: Anomura: Diogenidae) from shallow coastal waters in Japan.

A new species of diogenid hermit crab, Diogenes minimus, is described and illustrated on the basis of material from shallow subtidal waters (5-19 m) in central Japan. It appears close to D. holthuisi Asakura Tachikawa, 2010, but easily distinguished from the latter by the shape of the antennal acicle, non-elongate male left cheliped and the armature of the right cheliped merus. Including the new species, 14 identified species of Diogenes are now known from Japanese waters. A brief overview on species of Diogenes recorded from Japanese waters is given.

A new species of the hermit crab genus Diogenes Dana, 1851 (Decapoda: Anomura: Diogenidae) from southern India.

A new species of the hermit crab genus Diogenes Dana, 1851, D. spongicola, is described and illustrated on the basis of material collected from two locations off southern India. It appears close to D. takedai Rahayu, 2012 among about 70 congeners, but easily differentiated from the latter by the spinulose anterolateral margins of the shield, the article 2 of the antennal peduncle armed only with one distal spine, the longer, spinose antennal acicle, the absence of prominent spines on the ventrolateral margin of the cheliped meri, and the different color of the cheliped palm. Specimens of the new species were all collected from cavities of a callyspongiid sponge Callyspongia diffusa (Ridley, 1884), suggesting a possible association between the hermit crab and sponge.

Molecular phylogeny of ten intertidal hermit crabs of the genus Pagurus inferred from multiple mitochondrial genes, with special emphasis on the evolutionary relationship of Pagurus lanuginosus and Pagurus maculosus.

The hermit crab genus Pagurus exhibits high species diversity and a wide geological distribution. Despite the high species diversity of hermit crabs in the western Pacific coast of Japan, molecular phylogenetic studies of these species have yet to be conducted. To investigate their molecular phylogeny and genetic diversity, we obtained nearly complete mitochondrial genome sequences for ten Pagurus species found along the Pacific coast of Japan by next-generation sequencing, which were compared to other congeners deposited in the GenBank database. The genomes ranged from 13,458 to 16,401 base pairs in length, possessing 13 protein-coding genes, 2 rRNAs, and 22 tRNA genes. Based on the reconstructed phylogeny, we found that (1) Japanese Pagurus species separated into three groups, nested within the Northern Pacific species. (2) Pagurus lanuginosus and Pagurus maculosus, showed high morphological similarities, implying close kinship. Indeed, these two species were genetically closest to each other, compared to the remaining species studied. (3) An unspecified specimen sampled from the deep sea, which morphologically resembled Pagurus, might be a member of the Pagurus genus, but is genetically distant from the other Japanese Pagurus species. The novel data reported here may provide new perspectives for systematic studies of hermit crabs; these results provide important information that will facilitate population-level research and identifying intraspecific variation of these non-model, but ecologically important, decapod species.

A new species of the hermit crab genus Diogenes (Crustacea: Decapoda: Diogenidae) from the coast of KwaZulu-Natal, South Africa.

A new diogenid hermit crab with bright-white chelae, Diogenes albimanus n. sp., is described and illustrated, based on a single ovigerous female collected from KwaZulu-Natal, South Africa. The new species is compared to morphologically similar species, in particular to D. holthuisi and D. dorotheae, from which it is distinguishable by the shape and armature of the telson; and also to the superficially-similar South African D.extricatus, from which it differs by having the unarmed dorsal margins of the propodi and meri of the pereopods, as opposed to being armed with rows of strong spines. The unusually white chelae are similar in colour to those of D. takedai, but the coloration of all other parts is different in these two species. High quality macro photographs, a high-resolution microCT (μCT) scan of the whole animal, and the reference to the repository of the molecular barcode of the new species are provided.

Redescription of the pagurid hermit crab Catapaguroides fragilis (Melin, 1939) and descriptions of two new species from deep-sea off the Ryukyu Islands, Japan (Crustacea: Decapoda: Anomura).

Three species of the pagurid hermit crab genus Catapaguroides A. Milne-Edwards & Bouvier, 1892, all from Japanese waters, are reported. Catapaguroides fragilis (Melin, 1939) is redescribed on the basis of the holotype and additional material from southern Japan. Diagnostic characters of this poorly known species are fully assessed. Two new species, C. bythos and C. rubromaculatus, are described and illustrated on the basis of material from upper bathyal depths off the Ryukyu Islands. Catapaguroides rubromaculatus n. sp. resembles C. fragilis and C. hirsutus Komai & Rahayu, 2013, but the characteristic shape of the ocular peduncle and the elongate male right sexual tube with an anteriorly directed distal portion readily separate C. rubromaculatus n. sp. from the latter two congeners. Catapaguroides bythos n. sp. appears close to C. mortenseni de Saint Laurent, 1968 and C. pectinipes (Lewinsohn, 1969), but the different armature of the chelipeds distinguishes C. bythos n. sp. from the latter two allies. Catapaguroides is now represented by 30 species.

Paracapsulapagurus poponguinensis, a new hermit crab (Decapoda, Anomura, Paguroidea) from the Maastrichtian of Senegal

AbstractBased on a single right cheliped from the Cape de Naze Formation (middle–upper Maastrichtian), Senegal, a new genus and species of hermit crab with capsulated setae is described.Paracapsulapagurus poponguinensisn. gen. n. sp. is characterized by platy, scale-like, non-spinose tubercles with setae arranged in curved rows. This is only the third record of a fossil hermit crab with capsulated setae. These are documented in detail using SEM-imaging. For the first time, capsulated setae are also figured for the Early Jurassic hermit crabSchobertella.

A new species of the hermit crab genus Paguristes Dana, 1851 (Crustacea: Decapoda: Anomura: Diogenidae) from southwestern India.

A new species of the hermit crab genus Paguristes Dana, 1851 (Diogenidae), P. luculentus, is described and illustrated on the basis of three male specimens collected from off the Kerala State, southwestern India. It belongs to the species group characterized by the posterior lobes of the telson unarmed on the terminal margins, but the characteristic armature of the chelae and carpi of the chelipeds, consisting of a covering of numerous small corneous-tipped spines, and the presence of numerous small corneous-tipped or corneous spines on the mesial faces of the dactyli of the second pereopods immediately distinguish the new species from other congeneric species. The new species represents the ninth of the genus known from Indian waters.

A new species of the pagurid hermit crab genus Lophopagurus McLaughlin, 1981 (Crustacea: Decapoda: Anomura) from French Polynesia, and additional record of L. indonesiensis McLaughlin, 1997 from the Philippines.

Two species of the pagurid hermit crab genus Lophopagurus McLaughlin, 1981 are reported herein. Lophopagurus (Lophopagurus) minimus n. sp., described on the basis of two females from Tuamotu Archipelago, French Polynesia, appears closest to L. (L.) nanus (Henderson, 1888), but is easily distinguished from the latter by the different shape of the ocular peduncles and the less developed armature of the right cheliped. A single female from the Bohol Sea, the Philippines, is identified with L. (Australeremus) indonesiensis McLaughlin, 1997, a species for which possible synonymy with L. (A.) triserratus has been suggested. The newly collected specimen confirms the validity of the species and represents its second record since the original description.

Additional records of the pagurid hermit crab genus Trichopagurus de Saint Laurent, 1968 (Crustacea: Decapoda: Anomura), with description of a new species from the Philippines

The pagurid hermit crab genus Trichopagurus de Saint Laurent, 1968 is currently represented by three shallow water spe- cies from the tropical Indo-West Pacific region. In this paper, three species of the genus, including one new species, are reported. Trichopagurus tenuidactylus n. sp. is described on the basis of a single ovigerous female from the Bohol Sea, the Philippines, and compared with two close relatives, T. asper Komai & Poupin, 2012 and T. macrochela Komai & Os- awa, 2005. New locality records are provided for T. macrochela (the Philippines) and T. trichophthalinus (Forest, 1954) (Taiwan and Marianas). An identification key to the four species of the genus is presented.

Molecular analysis validates of some informal morphological groups of <i>Pagurus</i> (Fabricius, 1775) (Anomura: Paguridae) from South America

The systematics of the hermit crab genus Pagurus is complex, with a long history of taxonomic rearrangements. This group, with worldwide distribution, encompasses a large number of morphologically heterogeneous species. A total of 173 currently recognized species have been morphologically organized into 11 informal groups, in attempts to establish internal stability. This arrangement and the relationships among species of each informal group have remained obscure and have never been evaluated from a molecular phylogenetic viewpoint. Attempts to resolve these high-level classification problems have been restricted to morphological studies, with no satisfactory results because of the extensive overlap of the characters used. We evaluated the phylogenetic position of some of these informal groups of species of Pagurus occurring along the Pacific and Atlantic coasts of South America, using partial fragments of two molecular markers (16S mtDNA and Histone 3 nDNA). Our results indicated a clear polyphyletic arrangement of Pagurus; at the same time, the internal clades fit perfectly with pre-established informal morphological groups from South America, which may warrant a formal taxonomic subdivision of the genus. Additionally, the species belonging to the "provenzanoi group" clearly fit within a different taxon and should be reviewed. Also, the presence of the genus Propagurus in the ingroup could be interpreted by non-exclusive hypotheses: from one point of view, the genus Propagurus is nested within Pagurus, and therefore Pagurus is not valid as currently composed; or possibly, that more than one genus should be recognized among the South American species presently assigned to Pagurus. This latter perspective accords with the proposal to restrict Pagurus to only a few species.

A new species of the hermit crab genus Diogenes (Crustacea: Decapoda: Anomura: Diogenidae) from southern India

A new species of the hermit crab genus Diogenes Dana, 1851 (Diogenidae), D. canaliculatus, is described and illustrated on the basis of material from off the Kerala State, southern India. It is referred to the D. edwardsii (De Haan, 1849) species group, and compared with D. bicristimanus Alcock, 1905, D. fasciatus Rahayu & Forest, 1995, D. laevicarpus Rahayu, 1996 and D. moosai Rahayu & Forest, 1995. The characteristically sculptured left chela and the unarmed dorsal margins of the propodi of the second and third pereopods distinguish the new species from these congeners.

Records of the hermit crab genus Pagurixus Melin, 1939 (Crustacea: Decapoda: Anomura: Paguridae) from Europa Island, western Indian Ocean, with descriptions of two new species

Three species of the pagurid hermit crab genus Pagurixus Melin, 1939, are reported from Europa Island in the MozambiqueStrait, western Indian Ocean: P. haigae Komai & Osawa, 2007, P. annulus n. sp., and P. europa n. sp. Pagurixushaigae is recorded from the western Indian Ocean for the first time. Pagurixus annulus n. sp. and P. europa n. sp. arereferred to the P. boninensis (Melin, 1939) species group and P. anceps (Forest, 1954) group, respectively. Diagnosticcharacters of these two new species are discussed.

Records of four species of the shallow water hermit crab genus Diogenes (Crustacea: Decapoda: Anomura: Diogenidae) from southern China, with description of a new species

Four species of the hermit crab genus Diogenes Dana, 1851, are reported from the coast of Guandong Province, China, including one new taxon: D. acanthochela sp. nov., D. deflectomanus Wang and Tung, 1980, D. paracristimanus Wang and Dong, 1977, and D. rectimanus Miers, 1884. Diogenes acanthochela sp. nov., referred to the D. edwardsii (De Haan, 1849) species group, is characteristic in the spinose left chela lacking distinct crest on the outer surface, the possession of one prominent spine on the ventromesial margin proximally on the merus of the left cheliped, and the propodus of the left third pereopod armed with additional rows of spinules on the lateral surface. Detailed descriptions are provided for D. deflectomanus and D. paracristimanus, and their diagnostic features are fully reassessed. These two species are also referred to the D. edwardsii group. The occurrence of D. rectimanus in Chinese waters is fully confirmed.

A new species of the hermit crab genus Ciliopagurus Forest (Crustacea: Decapoda: Anomura: Diogenidae) from southern India

The diogenid hermit crab genus Ciliopagurus Forest, 1995 is currently represented by 18 recent species, 17 species fromthe Indo-West Pacific and one species from the eastern Atlantic. In this paper, we describe a new species, Ciliopagurusgrandis, from off Kerala State, southern India. This new species is compared with six congeneric species, C. albatrossiForest, 1995, C. caparti (Forest, 1952), C. krempfi (Forest, 1952), C. liui Forest, 1995, C. macrolepis Forest, 1995, and C. shebae (Lewinsohn, 1969). It is characteristic in having weakly armed antennal acicles.