Male Gnathopod Research Articles

Melitapanda, a new species of Melitidae (Crustacea, Amphipoda) from Japan.

A new intertidal species of the melitid amphipod, Melitapanda, from the Wakayama Prefecture, Japan, is identified and described. Melitapanda sp. nov. differs from the similar M.koreana and M.nagatai by its black-and-white body color, well-developed anterodistal projection of the male gnathopod 1 propodus, and telson armature. Molecular phylogenetic analyses based on the nuclear 28S rRNA and mitochondrial COI genes support that M.panda sp. nov. is closely related to M.koreana and M.nagatai.

On a small collection of Maeridae Krapp-Schickel, 2008 (Crustacea: Amphipoda) from Gujarat, India

The present study was based on amphipod specimens collected from the coastal areas of Gujarat state, India. From the collection, four species belonging to the family Maeridae Krapp-Schickel, 2008 were identified. Two species, Ceradomaera plumosa Ledoyer, 1973 and Ceradocus (Denticeradocus) alama Myers & Nithyanandan, 2016 are reported for the first time from Gujarat state and India, respectively. Two more species, Maera gujaratensis sp. nov. and Quadrimaera okha sp. nov. are described as new species. Maera gujaratensis sp. nov. can be differentiated from its closely related congener M. hirondellei Chevreux, 1900 on the basis of shape of male gnathopod 1 coxa and number of setae present on the telson. Quadrimaera okha sp. nov. can be differentiated from its closely related congeners Q. brownorum Hughes, 2015 and Q. caliban (Ruffo, Krapp & Gable, 2000) by the non-lobate anterodistal corner of gnathopod 2 basis, by the shape of the propodus of the male gnathopod 2, and in having a comparatively smaller uropod 3 peduncle to rami ratio.

On a small collection of amphipods (Crustacea, Amphipoda) from Chilika Lake with the description of three new species and a new genus

The current study was conducted on the basis of a small collection of amphipods made from Chilika Lake that contained 4 species. Three were described as new species, including one new genus: Parhyale kalinga sp. nov., Chilikorchesta chiltoni gen. nov. sp. nov. and Grandidierella rabindranathi sp. nov., while a fourth one was a previously reported species: Quadrivisio bengalensis Stebbing, 1907. Parhyale kalinga sp. nov. can be differentiated from its closely related congeners Parhyale basrensis Salman, 1986 and Parhyale darvishi Momtazi & Maghsoudlou, 2016 by having male gnathopod 2 propoduswith 2 robust setae at the base of the palm and 2 small setae slightly behind the palm and dactylus much smaller than palm. Chilikorchestia chiltoni gen. nov. sp. nov. can be differentiated from the closely related genus Morinoia Lowry & Myers, 2019 by its incrassate male antenna 2 and untapered telson. Grandidierella rabindranathi sp. nov. can be differentiated from its closely related congeners G. mahafalensis Coutière, 1904 and Grandidierella nioensis Myers, Sreepada & Sanaye, 2019 by having male gnathopod 2 carpus oval shaped with both margins convex.

Three species of the family Aoridae Stebbing, 1899 (Crustacea: Amphipoda) collected from remote islands in southern Japan, with a key to all Japanese species of the family

Three species of the aorid amphipod were collected from remote islands in southern Japan. Protolembos ryukyuensis sp. nov. was collected from Ishigaki Island in Okinawa Prefecture and Tanegashima Island in Kagoshima Prefecture, and characterized by the dense plumose setae on the male gnathopods 1 and 2. Tethylembos cavatus sp. nov. and T. japonicus Ariyama, 2004 were collected from Miyake Island and the Ogasawara Islands in Tokyo Prefecture, respectively. Both species share the male gnathopod 1 propodus heavily setose medially; however, Tethylembos cavatus can be distinguished from T. japonicus in the excavated basis of the male pereopod 5. Keys to species of Protolembos Myers, 1988 and Tethylembos Myers, 1988 in the world and a key to all Japanese species of the family Aoridae are provided. Number of aorid species in Japan stands at 34.

A new species of amphipod of the genus Parhyale Stebbing, 1897 from Chilika Lagoon, India.

A new species of the genus Parhyale, Stebbing 1897 was collected from the intertidal region of Chilika Lagoon associated with the seaweed Gracilaria sp. Parhyale odian sp. nov. differs from other species of the genus by having a stout robust seta on the surface of the propodus near to dactyl hinge of male gnathopod 1. With the new description of P. odian sp. nov., the global species number in the genus rises to 16.

New species of Ampithoe Leach, 1814 from Todos-os-Santos Bay, Bahia State, Brazil

ABSTRACTAmpithoe is one of the most diverse genera of Ampithoidae, commonly found in shallow waters associated with algae. This genus is distinguished by the absence of antenna 1 accessory flagellum, pereopods 5–7 not prehensile and uropod 1 spur absent. From Brazil, only four species are hitherto known, which are A. thaix, A. robustimana, A. ramondi and A. marcuzzii. In the present study, we describe a new species of Ampithoe from Todos-os-Santos Bay, Northeastern Brazil, found associated with the sponge Clathria. The new species is unique by showing mandibular palp thin and reduced, male gnathopod 1 propodus palm very short and setose, male gnathopod 2 propodus palm acute, with a tooth near hinge of dactylus. A taxonomic key to Ampithoe of the world is provided.http://www.zoobank.org/urn:lsid:zoobank.org:pub:F1FF8E18-BCDA-45F7-8B42-85552B094707http://www.zoobank.org/urn:lsid:zoobank.org:act:49F7BB4F-8AF5-46DA-B470-10114085E420

A new species of Cerapus (Amphipoda, Senticaudata, Ischyroceridae) from Mae Klong Estuary, with a discussion on their nesting and types of mating behaviour

The first representative of the genus Cerapus in the Gulf of Thailand, Cerapus rivulus sp. nov., is described from specimens sampled from Mae Klong Estuary, the inner Gulf of Thailand. The main identifying characteristics of this new amphipod species are pereonites 1 and 2 without constriction; male gnathopod propodus palm transverse with long posterior defining tooth and well-developed anterodistal recurved tooth adjacent to propodus articulation; pereopod 6 coxa without fine fringe setae ventrally, basis with setae on posterior margin; and telson with deep cleft. An updated identification key for the 25 known species in the genus is also presented. A discussion on their nesting and types of mating behaviour is provided.

Talorchestia buensis sp. nov. (Senticaudata, Talitridae), a new species of amphipod from West Bengal, east coast of India.

In coastal regions, Talitrids are found among decaying material in the supralittoral zone of sandy beach, mangroves and delta regions. Five genus and five species of the family Talitridae have been reported so far from Indian coastal waters. A new species of the amphipod genus Talorchestia Dana, 1852, Talorchestia buensis sp. nov. was collected from Kadirabad Char, West Bengal, east coast of India. The species was collected from a sandy beach, beneath dead leaves. The new species can be distinguished from other described species of the genus by the presence of a double rows of setae on the endopod of uropod 2, the presence of more than 10 robust setae in each lobe of the telson, antenna 2 reaching more than half the body length, pereopod 7 longer than pereopod 6 and by the absence of a distal protuberance on the palm of male gnathopod 2. The present article increases the total number of world species in the genus to 26.

A new species and a new record of the amphipod genus Cymadusa Savigny, 1816 (Senticaudata, Ampithoidae) from India.

The present study recorded Cymadusa filosa Savigny 1816 for the first time from India along with the description of a new species Cymadusa kaureshi n. sp. The newly described species C. kaureshi n. sp. can be differentiated from its closely related congeners C. setosa (Haswell, 1879) and C. tattersalli Peart, 2004 in having 3 articulated accessory flagellum of antenna 1 and male gnathopod 2 palm with small proximal knob-like process. The record of Cymadusa filosa Savigny, 1816 by Rabindranath (1972) from Tamil Nadu does not match with the description and illustrations of C. filosa sensu stricto in having mid palmar tooth on male gnathopod 2; antenna 1 with 3 articulated accessory flagellum and gnathopod 1 significantly longer and slender than gnathopod 2. Since the record of Rabindranath (1972) significantly differs from C. filosa sensu stricto, we assume that the Tamil Nadu specimen could be an undescribed species. Moreover, all the previous reports from India of C. filosa are erroneous, and here in this study we report the first confirmed record of C. filosa from India.

Pseudaeginella makranensis sp. nov., a new species of caprellid (Crustacea: Amphipoda) from the Iranian coasts of Gulf of Oman.

Pseudaeginella makranensis sp. nov. is described from the Iranian coast of the Oman Sea. This species differs from other Pseudaeginella species by setose antennae, setae arrangement on mandibular palp, basis of male gnathopod 2 larger than pereonite 2, and bearing subrectangular propodus in second male gnathopod. A key to all species of Pseudaeginella Mayer, 1890 is provided.

South America stygobiont crustaceans: a new species of Hyalellidae (Amphipoda) and new reports of Stygocarididae (Anaspidacea) and Protojaniridae (Isopoda) from Calingasta Valley, Pre-Andean region, San Juan, Argentina

We describe one new eyeless Hyalella species, H. cuyana n. sp., from the hyporheic zone of Calingasta River, San Juan Province, Argentina. Hyalella cuyana n. sp. differs morphologically from its stygobiont congeners by characters of antennae (both antennae subequal in size; aesthetascs elongated); coxal plate 4 (posteriorly without excavation); epimeral plates 1-3 (rounded posterodistally); male gnathopod 2 propodus (almond-shaped, ovate, palm slope strongly oblique); and pleopods (inner ramus reduced to 2-3 articles). We provide a detailed morphological comparison between stygobiont and stygophile Hyalella species. We comment on the sympatry and new report of stygobiont Malacostraca species Parastygocaris andina and Cuyojanira sp. Severe environmental changes and significant decline of habitat quality recorded along the Calingasta River increase the risk of extinction for this vulnerable and endemic fauna. We recommend that the new Hyalella species should be listed as Critically Endangered (CR) in the IUCN categorization according to criteria B1a as it is only known from the type locality; and criteria B1b iii (continuing decline, observed, inferred in the quality of habitat).

Three new species of the family Aoridae collected from Sagami Bay, central Japan (Crustacea: Amphipoda)

Three new species of the amphipod family Aoridae Stebbing, 1899 were collected from the bottom of a 40400 m depth in Sagami Bay, central Japan. Aora biarticulata sp. nov. is characterized by the accessory flagellum with 2 articles, the weakly setose male gnathopod 1 and the male gnathopod 2 with setose carpus and propodus. Aoroides sagamiensis sp. nov. has a distinctive male gnathopod 1 with poorly setose basis and heavily setose merus. Grandidierella gracilis sp. nov. has stridulating ridges on the carpus of the male gnathopod 1. This new species can be distinguished from its related congeners by the teeth arrangement on the male gnathopod 1 carpus, the poorly setose antennae, the sparsely setose posterior margins of the pereopods 6, 7 bases, and the ordinary form of the male gnathopod 2.

The morphological diversity within a species can obscure the correct identification

Critical points of various diagnostic characters and a paucity of information relating to the geographical distribution of several marine species can hinder real species delimitation, particularly if they are supposed to be cosmopolitan. Such constraints characterize many amphipod species and are mainly due to the variation in morphological characters during growth. Specifically, the benthic filter-feeding corophiid Cheiriphotis mediterraneaMyers, 1983 displays different shapes for the male gnathopod 2 as it grows. This variation has hitherto never been described but an extensive sampling has provided us with the opportunity of studying it in detail. More than six thousand individuals, belonging to C. mediterranea, were collected along the Israeli coast during a five-year soft-bottom monitoring survey, comprising 282 sites at a depth between 4 and 37 m. One of the objectives of this study was to integrate the original description of C. mediterranea with the identification of definite six morphotypes, which alternate during growth. A mtDNA Cytochrome c oxidase subunit I sequence was obtained, representing the first molecular datum for the genus Cheiriphotis. The results offer the possibility of including variable morphological characters and molecular sequences in the identification process. Throughout the survey, C. mediterranea was confirmed to be one of the most abundant five species in the study area, in particular in Haifa Bay, where the environmental conditions are stressful. Barely-known abundance and distribution notes relating to this species are reported in this paper; a putative role of bioindicator is also suggested.

An integrated taxonomic approach, using geometric morphometric methods, reveals the cryptic diversity of Parhyale darvishi Momtazi & Maghsoudlou, 2016 (Crustacea: Amphipoda: Hyalidae)

In recent years, morphological analyses and molecular methods have been increasingly used to describe new species of amphipods. Geometric morphometric methods are recognized as part of an integrated approach in taxonomy and are a cost-effective way to identify species, but its application is rare in Amphipoda. Taxonomically, the shape of gnathopods is important in the family Hyalidae, and species could be identified based on changes in these anatomical parts. Previously, Parhyale darvishi Momtazi & Maghsoudlou, 2016, had been described as a very scattered amphipod on a wide range of northern coasts of the Persian Gulf and the Gulf of Oman. In the present study, a geometric morphometric method based on semilandmarks was used to investigate intraspecific gnathopod's shape changes of P. darvishi population in the Persian Gulf and the Gulf of Oman. Therefore, 180 semilandmarks were selected on the propodus of first and second gnathopods of 100 male and 50 female. Data were analysed using tps package software. The results of UPGMA clustering and relative warp analysis reveal cryptic diversity in P. darvishi and show the main morphometric variations between sexes and populations. The present results, clearly separated Bushehr population samples from other studied populations of P. darvishi with concave posterio-distal margin in propodus of first and second male gnathopods and subquadrate propodus of first female gnathopod. Surveying detailed morphology of Bushehr samples confirmed geometric morphometric results. Therefore, Parhyale bushehrisp. nov. was described and distinguished from similar species by revealed propodus shape variations of geometric morphometric analyses and also having setae on the outer ramous of first and second uropods, peduncle of third uropod and some mouthparts characters. Consequently, the results show the integrated approach (numerical variations and statistical analyses along with morphological analyses) in amphipod taxonomy could reveal cryptic diversity.

A newHyalella species (Crustacea: Amphipoda: Hyalellidae) from South American Highlands (Argentina) with comments on its cuticular ultrastructure.

Hyalella Smith, 1874 includes approximately 92 species present only in the Neotropical and Nearctic regions. Hyalella is a dominant taxon in Central Andean Highland wetlands of Northwestern Argentina. We describe a new Hyalella species from Chorrillos, a cold-hyperfresh Puna peatbog in Salta province. Two other species occur in the Puna biogeographic province, namely H. kochi Gonzlez Watling, 2001 and H. puna Peralta Isa Miranda, 2019. The new species differs from H. puna mainly in having a smooth body surface; propodus of male gnathopod 1 hatchet-shaped, with nine serrate setae on inner margin; uropod 3 peduncle with two strong distal setae; and number and distribution of telson setae; from H. kochi by having the male uropod 1 without modified curved seta on inner ramus; six sternal gills on pereionites II-VII; globose peduncle of uropod 3 with two strong distal setae; long palp of maxilla 1. We also compared its external morphology with that of H. fossamancinii Cavalieri, 1959, another species recorded in the High Andes. We contribute new details on ultrastructural morphology of cuticular extensions (setae; microtrichs; denticles and pores). With this new species, the number of known Hyalella species in Argentina and Falkland Islands (Islas Malvinas) rises to 13.

A new species of Ampithoe (Amphipoda, Ampithoidae) from Korea, with a redescription of A.tarasovi.

An ampithoid species, previously known as A.tarasovi in Korea, is assigned as a new species, A.changbaensissp. nov. based on the reexamination of the holotype of A.tarasovi. The new species shows different morphological characteristics compared to A.tarasovi, especially in male gnathopods 1 and 2. The type material of A.tarasovi is redescribed and illustrated here and a key to the Korean species of Ampithoe is provided.

The competition of native sponges and the sun coral Tubastraea spp. does not influence the morphological pattern of a new Photis (Photidae: Senticaudata)

ABSTRACT In the marine environment competition between sessile organisms may influence habitat conditions for associated small invertebrates, acting as a selective pressure for individuals with suitable traits to select profitable habitats and leading individuals less adapted to occupy unfavourable habitats. Intraspecific competition may also influence the habitat selection of marine amphipods in different habitat conditions. In the present study, we describe a new Photis species (Photidae: Senticaudata) and analyse its morphological variation influenced by different habitat conditions. Photis oxalai sp. nov. is unique in showing the male gnathopod 1 propodus ventral margin rounded with a spine near the hinge of the dactylus and male gnathopod 2 propodus palm with three pronounced spines and a mesial excavation. This is the first record of the genus in Bahia State. We compared individuals associated with sponges in direct competition with Tubastraea spp. (Scleractinia: Dendrophylliidae) and individuals associated with sponges that were established free from this interaction, analysing morphological traits influenced by the competition between hosts. We did not record any differences in morphological patterns; therefore, the pattern of morphological variation among individuals is not influenced by habitat conditions that emerged from the competition of the host with the sun coral. Photis oxalaisp. nov. shows a generalist behaviour in habitat selection at the local scale, suggesting that this species may not be a profitable model for studying the influence of the sun coral on native communities. http://www.zoobank.org/urn:lsid:zoobank.org:pub:3A5483E5-F096-4D91-B9FB-27A120F1E00A

A new species of Deutella (Amphipoda: Caprellidae) from the Gulf of Mexico

A new species of the genus Deutella Mayer, 1890 is described and illustrated, and a key to identify the Deutella species from the Gulf of Mexico is given. The specimens were collected from coral rubble at 18 m depth in Tuxpan-Lobos coral reef system, W Gulf of Mexico. Deutella pseudoincerta n. sp. is remarkably close to Deutella incerta (Mayer, 1903), but can be easily distinguished by: length and shape of pereopod 5 especially distal article; length and width of adult male gnathopod 2; shape and size of tubercles in male abdominal appendages. The new species increases the number of Deutella species to 14 worldwide, and 18 species of Caprellidae from the Gulf of Mexico.

Pleonexes Spence Bate, 1857 (Amphipoda: Ampithoidae) in the Persian Gulf and the Gulf of Oman.

A new species of ampithoid amphipod, Pleonexes nargessi, is described from the southern Iranian coasts of the Persian Gulf and the Gulf of Oman. The new species is the most similar to P. kava (Myers, 1985), but distinguished by the presence of the posterior tooth and the defining robust seta on the palm of male gnathopod 1, semi prehensile pereopod 5, and non-prehensile pereopods 6-7. Ampithoe qeshmensis Layeghi Momtazi, 2018 is transferred into Pleonexes.

A new crab-associated amphipod of the genus Isaeopsis Barnard, 1916 (Amphipoda: Senticaudata: Ischyroceridae) from southern Chile.

A new species of amphipod of the family Ischyroceridae is described. Isaeopsis chiloensis n. sp. was discovered in association with the cancrid species Metacarcinus edwardsii and Romaleon setosum, in the inner sea around Chiloé Island, in Southern Chile. This represents the second species of the genus Isaeopsis, a group formerly known only from South African waters. The new species is characterized principally by the structure of the gnathopods, the propodus of pereopods 3-7 and the ornamentation of the outer ramus of uropod 3. The male gnathopod 2 has a prominent thumb in the posteroproximal margin of the propodus and the pereopods 3-7 are subchelate with the palm armed by a row of at least five strong setae. In addition, the apex of the outer ramus of uropod 3 bears a comb with more than thirty fine teeth. Isaeopsis chiloensis n. sp. is completely described and a series of illustrations is provided.