Monstrilloid Copepod Research Articles

A new species of the genus Monstrilla (Copepoda: Monstrilloida: Monstrillidae) from the Gulf of California, Mexico

Based on deep-water (700-750 m) biological samples obtained from the southern Gulf of California, Pacific coast of Mexico, a new species of the monstrilloid copepod genus Monstrilla Dana, 1849 is described based on a single subadult female collected close to the bottom with an epibenthic sledge. Monstrilla hendrickxi sp. n. is distinguished by a unique combination of characters including: 1) no trace of eyes; 2) strong, thick antennules with segments 2-4 partly fused; 3) strongly developed apical elements on antennular segment 5 and spinous processes on segments 2-5; and 4) bilobed fifth legs with 2 apical setae on the exopodal lobe and a digitiform, unarmed endopodal lobe. The new species exhibits some affinity with surface-dwelling species of Monstrilla that have 2 setae on the exopodal lobes of the fifth legs. This is the fifth record of a species of the order Monstrilloida in the Gulf of California. The present discovery in deep oceanic waters significantly adds to our knowledge of the habitat range of this copepod order and likely anticipate further interesting findings of monstrilloids in deep waters worldwide.

Updating the zooplankton species list for the Belgian part of the North Sea

Many marine species are threatened, and given the importance of biodiversity indices in the current European marine policy, taking stock of existing species and species diversity is crucial. Zooplankton form the basis of the pelagic food web, acting as staple food for fish larvae and adult pelagic fish, but are very susceptible to a changing climate. Inventorying zooplanktonic diversity is therefore important. Based on monthly sampling campaigns in 2009 and 2010, an update is provided on the zooplankton species list for the Belgian part of the North Sea. A total of 137 taxa are listed, some of which had rarely or never been observed in the area. This inventory revealed several species new to the Belgian marine species list: the calanoid copepod Metridia lucens, the cyclopoids Oithona similis and Giardella callianassae, the hydrozoans Amphinema dinema and Eutima gracilis, the mysid Acanthomysis longicornis, the polychaete worm Tomopteris helgolandica, the cladoceran Penilia avirostris and the monstrilloid copepod Cymbasoma germanicum. Additionally, we identified several males of C. germanicum, which have never been described before. Brief discussions are presented on spatial distribution and abundance of all taxa.

Two new species of Monstrilla (Copepoda: Monstrilloida: Monstrillidae) from a protected reef system of the Mexican Caribbean

Several adult female monstrilloid copepods, collected in March 2022 from the protected reef area of Xcalak, on the southern part of the Mexican Caribbean coast, proved to belong to two undescribed species of Monstrilla Dana, 1849. They are described here as M. xcalakensis sp. nov. and M. annulata sp. nov., partly by use of scanning electron microscopy. Females of the two species are generally similar but differ in: (1) antennular segmental structure, (2) antennular armature and ornamentation, (3) structure and setation of the fifth leg, (4) number and modifications of the caudal setae, and (5) integumental ornamentation. Comparison with congeneric species revealed distinctive features for both species that support their status as new. These two species are interesting additions to the reef-dwelling monstrilloid copepod fauna of the Mexican Caribbean and confirm Monstrilla as the most diverse genus of monstrilloids in this area, now represented by nine species.

Two new species of Cymbasoma (Multicrustacea: Copepoda: Monstrilloida: Monstrillidae) from the North Atlantic

ABSTRACT Monstrilloid copepods are protelean endoparasites of benthic invertebrates. Their adult free-living stage is chiefly found in the plankton of shallow coastal systems, estuaries and coral reefs; there are no previous records of monstrilloids from deeper marine habitats including epipelagic or mesopelagic waters. Two new species of the monstrilloid copepod genus Cymbasoma Thompson, 1888 are described based on adult females incidentally captured by an epibenthic sledge operated at a depth range of 118–302 m off north-west Iceland and the Norway Channel. Cymbasoma norvegicum sp. nov. is distinguished by a combination of characters including a long, constricted anal somite, bilobed fifth legs with long inner lobe, antennules with fused segments, and first antennule segment unarmed. Cymbasoma pedroi sp. nov. has a pair of rounded posterolateral protuberances on the genital somite, fused fifth legs lobes, and an anteriorly produced, ornamented forehead. Both species are considered new members of the Cymbasoma rigidum species group, widely distributed in different geographic areas but not previously known from epi-mesopelagic depths. The finding of these new species represents the first discovery of monstrilloids at epi-mesopelagic depths in the Pacific Ocean and it significantly adds to our knowledge of this copepod order, thus highlighting their potentially high yet unstudied diversity in deeper waters. http://www.zoobank.org/urn:lsid:zoobank.org:pub:C05EEC28-9936-41CB-BC9E-D990AE53B3B1

First record of Caromiobenella helgolandica (Claus, 1863) (Copepoda, Monstrilloida) from the Saudi waters of the Arabian Gulf

Caromiobenella helgolandica (Claus, 1863), a presumedly widespread monstrilloid copepod, is reported for the first time from Saudi waters of the Arabian Gulf; only females were found in zooplankton samples collected from Tarut Bay in the Arabian Gulf. Caromiobenella Jeon, Lee, & Soh, 2018 is a recently described genus that is distinguished by having modified male antennules. The nauplii of monstrilloid copepods are endoparasitic on molluscs and polychaetes, while the adults are free-living reproductive forms. This study is an unprecedented record of C. helgolandica from the Arabian Gulf region.

A new species of Monstrilla (Crustacea: Copepoda: Monstrilloida: Monstrillidae) collected by the R/V Albatross (1908) from the Sulu Sea, Philippines

ABSTRACT Monstrilloid copepods are protelean parasites of various groups of benthic invertebrates. The taxonomy of some monstrilloid genera is still in development. The re-examination of museum collections and redescription of the earliest described species have proven to be useful tools to unravel some of these problems. An examination of monstrilloid specimens collected from the Philippines area by the US Steamer Albatross in 1908 and deposited in the National Museum of Natural History, Washington, DC, revealed the presence of a male specimen representing an undescribed species of the genus Monstrilla. The new species is described and illustrated following current standards in monstrilloid copepod taxonomy. It can be easily distinguished from its congeners by the unique cuticular ornamentation pattern on its cephalothorax, the number of caudal setae, and details of its geniculate antennules and genital complex. http://www.zoobank.org/urn:lsid:zoobank.org:pub:1FAF5CD7-6EF9-4405-8572-22E46F32A359

Record of Caromiobenella (Copepoda, Monstrilloida) in Brazil and Discovery of the Male of C. brasiliensis: Morphological and Molecular Evidence

Monstrilloid copepods are protelean parasites with a complex life cycle that includes an endoparasitic juvenile phase and free-living early naupliar and adult phases. The monstrilloid copepod genus Caromiobenella Jeon, Lee and Soh, 2018 is known to contain nine species, each one with a limited distribution; except for two species, members of this widespread genus are known exclusively from males. Hitherto, members of Caromiobenella have not been recorded from tropical waters of the South Western Atlantic (SWA). The nominal species Monstrilla brasiliensis Dias and Suárez-Morales, 2000 was originally described from female specimens collected in coastal waters of Espírito Santo and Rio de Janeiro (Brazil), but the male remained unknown. The failure to reliably link both sexes of monstrilloid species is one of the main problems in the current taxonomy of the group, thus leading to a separate treatment for each sex. New zooplankton collections in coastal waters and intertidal rocky pools of the SWA yielded several male and female monstrilloid copepods tentatively identified as Monstrilla brasiliensis. Our results of both morphologic and molecular (mtCOI) analyses allowed us to confirm that these males and females were conspecific. We also found evidence suggesting that Caromiobenella is not a monophyletic taxon. Our male specimens are morphologically assignable to Caromiobenella, therefore, females of the nominal species Monstrilla brasiliensis, are matched here with the aforementioned males and, thus, the species should be known as C. brasiliensis comb. nov. (Dias and Suárez-Morales, 2000). This finding represents the third documented discovery of a female of Caromiobenella, the first record of the genus in the Southwestern Atlantic, and the first documented record of monstrilloids from coastal tidepools. With the addition of C. brasiliensis, Caromiobenella now includes 10 valid species worldwide. This work represents the second successful use of molecular methods to link both sexes of a monstrilloid copepod. The male of C. brasiliensis is herein described, and a key to the known species of Caromiobenella and data on the habitat and local abundance of C. brasiliensis are also provided.

A new species of Cymbasoma Thompson, 1888 (Copepoda: Monstrilloida) from the Fujian coast, China

A new monstrilloid copepod species, Cymbasoma cheni sp. nov., from Meizhou Bay (an embayment in Fujian Province, southeastern China) is described and illustrated. The diagnostic character of the new species is the structure and armature of the fifth leg, which is represented by a single lobe armed with three naked setae subequal in length. The new species closely resembles Cymbasoma bowmani Suarez-Morales and Gasca, 1998 in the structure of the fifth legs, and the body proportions, including total body length, and relative lengths of the cephalothorax and the genital double somite. However, Cymbasoma cheni sp. nov. is distinguished by lack of cuticular ornamentation on the cephalothorax, the position of the oral papilla, and the structure of the fifth leg with three naked setae. Although the structure of the fifth legs is similar in Cymbasoma cheni sp. nov. and Cymbasoma quintanarooense (Suarez-Morales, 1994), the new species can be easily distinguished from Cymbasoma quintanarooense by the relative length of the antennule, differences in the genital double-somite and the ovigerous spines, and the shape of ocelli. This is the sixth record of this genus from China seas.

First use of molecular evidence to match sexes in the Monstrilloida (Crustacea: Copepoda), and taxonomic implications of the newly recognized and described, partly Maemonstrilla-like females of Monstrillopsis longilobata Lee, Kim & Chang, 2016.

Two forms of the monstrilloid copepod, one represented by males, the other by females, were dominant among the monstrilloids collected while sampling zooplankton with a light trap in southern coastal waters of Korea. Morphological examination revealed that the males are conspecific with the previously reported and rather specialized Korean species Monstrillopsis longilobata Lee, Kim & Chang, 2016, hitherto known only from males that have extremely long genital lappets. The females also show several diagnostic features of Monstrillopsis, such as prominent eyes, bilobed fifth legs with the inner lobe unarmed and reduced, and four urosomal somites. In addition, though, these females are extraordinary among all Monstrilloida in that their ovigerous spines are directed ventrally, not posteriorly as in most species or anteriorly as in those assigned to Maemonstrilla. Genetic divergence analyses based on partial mitochondrial cytochrome c oxidase subunit I, complete Internal Transcribed Spacer 1 (ITS1)–5.8S–ITS2, and partial 28S rRNA revealed little or no genetic divergence between the present males and females, thus demonstrating that they are mutually conspecific. The present report (1) provides the first morphological description of female M. longilobata with the proposal of a revised nomenclature for antennular setal armament; (2) presents the molecular evidence for conspecificity of the males and females; and (3) lists several morphological characteristics that are sexually dimorphic in this species, and thus likely also in other monstrilloids. Matters bearing on the validity of the genera Haemocera, Monstrillopsis, and Maemonstrilla are discussed.

A new species of Monstrillopsis (Crustacea, Copepoda, Monstrilloida) from the lower Northwest Passage of the Canadian Arctic.

A new species of monstrilloid copepod, Monstrillopsis planifrons sp. n., is described from an adult female that was collected beneath snow-covered sea ice during the 2014 Ice Covered Ecosystem – CAMbridge bay Process Study (ICE-CAMPS) in Dease Strait of the Canadian Arctic Archipelago. Currently, up to six species of this order are known to occur in polar latitudes. The new species described herein shares similarities with Monstrillopsis dubia (Scott, 1904) but differs in its body proportions and cephalothorax ornamentation; the cephalothorax is covered by minute scattered papillae on dorsal and ventral surfaces; this species has a reduced fifth leg endopod, fifth leg exopod armed with three setae, antennule with fused segments 3–4, and the genital double-somite bears unique posterolateral processes. This is the second species of this genus recorded in the Arctic, after Monstrillopsis ferrarii (Suárez-Morales & Ivanenko, 2004), described from the White Sea, and is the first record of Monstrillopsis in Canadian waters. With the addition of this new species and the recognition of Monstrillopsis bernardensis comb. nov. as a member of this genus, the number of nominal species is now 15. Overall, this genus has a tendency to be distributed in temperate and cold waters, while only three species have been found in tropical and subtropical latitudes.

A new species of Monstrilla Dana, 1849 (Copepoda: Monstrilloida: Monstrillidae) from Korea, including a key to species from the north-west Pacific.

A new species of monstrilloid copepod belonging to the genus Monstrilla Dana, 1849 is recorded from South Korea. Specimens were obtained between May of 2012 and January of 2014 from inshore waters along the coasts of the East Sea, South Sea, and Jeju Island, using a light trap installed at quays and wharves overnight. Monstrilla ilhoii sp. nov. is characterized by a remarkable combination of a large body size (females about 3.8 mm long, males about 2.8 mm long), a polygonal ridge pattern (cuticular reticulation) over the entire body surface, and an antennule armature featuring a supernumerary spiniform seta (4d₃) in females and a dagger-shaped distal spine (6₂) in both sexes. In other respects M. ilhoii sp. nov. most closely resembles M. lata Desai & Bal, 1963; both species have one and three setae on the endopodal and exopodal lobes, respectively, of female leg 5, a horseshoe-shaped male genital apparatus with marked undulations along the whole distal margin, and six setae on each caudal ramus in both sexes. This paper provides a description of the new species, taxonomic remarks on its morphological features, and differential diagnoses with respect to its allies. Scanning electron microscopy was used to document significant morphological microcharacters. The species of Monstrilla known from five sub-regions of the north-west Pacific are enumerated with the source references, and keys to the females and males of these species are provided.

Two New Records of Monstrilloid Copepods (Crustacea) from Korea

Two monstrilloid copepod species belonging to the genus Monstrilla Dana are newly recorded from Korea: M. grandis Giesbrecht, 1891 and M. hamatapex Grygier and Ohtsuka, 1995. Specimens were obtained from inshore waters around the coasts of South Korea, using a light trap installed at quays and wharves overnight. Based on the Korean specimens, the two species are redescribed, with brief accounts of their affinities and morphological variabilities. Remarkable morphological discrepancies are confirmed in female leg 5 of M. grandis between type material from Southern Hemisphere and European and Asian specimens, which raise a strong doubt on their conspecificity. Korean specimens of M. hamatapex well coincide with the type specimens from Japan, except for some variations in the setal armature of leg 5 and antennules. This is the second taxonomic paper on the monstrilloid copepods in Korea, and the genus Monstrilla is newly added to Korean fauna.

Historical record and supplementary description of Cymbasoma bullatum (A. Scott) (Copepoda: Monstrilloida) from the " Albatross " cruise in the Philippines

A male monstrilloid copepod of the genus Cymbasoma Thompson, 1888, collected in 1908 by the U.S. Fisheries Steamer Albatross off Mindanao, Philippines, and deposited in the U.S. National Museum of Natural History, was originally identified and labeled as Monstrilla leucopsis (sic) Sars, 1921 by C. B. Wilson. Reexamination of this historical sample revealed that the specimen is in fact assignable to Cymbasoma bullatum (A. Scott, 1909), described from specimens collected in 1899 in the Moluccan Sea during the Dutch Siboga Expedition. My earlier redescription of this species, based on the incomplete, damaged specimens of the type lot, lacked taxonomically relevant details and is supplemented herein. This species can be distinguished from its congeners by a combination of characters including the body proportions, armature of the antennules, presence of an anterior rostral protuberance, and structure of the genital lappets. New characters for distinguishing males of Cymbasoma species are evaluated. A relatively recent (1981) record of C. bullatum in Japan was evaluated in the light of these new data. Several differences in, e.g., antennulary armature, proportions of fifth pedigerous and anal somites, and morphology of the genital lappets, suggest that the Japanese specimens represent an undescribed taxon.

Validation and redescription of Cymbasoma germanicum (Timm) (Crustacea: Copepoda: Monstrilloida) from Helgoland with comments on Cymbasoma rigidum Thompson

Reexamination of a monstrilloid copepod collected in 1892 at Helgoland, Germany and deposited in the Zoological Museum (Berlin) offered the opportunity of (1) providing a complementary redescription of Cymbasoma germanicum (Timm) from its type locality, and (2) reviewing the taxonomical status of Cymbasoma rigidum Thompson 1888, and its presumed cosmopolitan distribution. Cymbasoma germanicum can be distinguished from the different morphotypes related to the nominal species C. rigidum by a combination of characters, including a large inner lobe of the fifth leg, an innermost fifth leg seta almost as long as the other two, the relative length of the antennules, and the presence of long elements 2v and 2d on the second antennular segment. The main distinguishing character is the presence of two knob-like processes on the posterior margin of the genital somite. Based on differences in several characters but mainly on the taxonomically important structure of the fifth legs, at least three distinct morphological patterns were detected among the main historical records of C. rigidum. This variability, the uncertainty of the identity of the original specimen, and the geographic amplitude of the records of C. rigidum suggest that the nominal species represents a taxonomic complex with several undescribed taxa.

Two New Species of <i>Monstrillopsis</i> Sars (Crustacea: Copepoda: Monstrilloida) from the White Sea and Norway, with Comments on <i>M. dubia</i> Scott

A new species of monstrilloid copepod, Monstrillopsis ferrarii n. sp., based on four adult female specimens collected in the White Sea, northern Russia, is described and illustrated. The new species is most closely related to M. dubia Scott from Scotland and the Mediterranean and M. dubia (sensu Sars, 1921) from Norwegian fjords. The latter is considered to represent a distinct species, described herein as M. dubioides n. sp. It differs from M. dubia in characters related to antennule length compared to body length, but mainly to the shape and relative size of the genital double somite and other urosomal somites. Records of M. dubia in Norway and off Lisbon are referable to M. dubioides n. sp. On the other hand, M. ferrarii n. sp. differs from M. dubia, M. dubioides, and the other species of the genus by a combination of characters, including 1) two rounded protuberances in the cephalic area, flanking the ocelli; 2) a wide zone of transverse cuticular striations encircling the cephalic area; 3) very long exopodal setae on the fifth legs, with no distal elongation of the exopodal lobe beyond the setal bases; 4) a relatively long genital double somite with the margins of the anterior half produced laterally; and 5) the nearly equal sizes of the anal somite and the preceding somite. It is considered that M. dubia and related forms represent a species complex with subtle morphological differences and a wide distribution. This is the first record of a species of Monstrillopsis in Russia and the sixth species of this order to be recorded in polar environments.

SUPPLEMENTARY DESCRIPTION AND ILLUSTRATED RECORD OF MONSTRILLA GIBBOSA SUÁREZ-MORALES & PALOMARES-GARCÍA, 1995 (COPEPODA, MONSTRILLOIDA) FROM SINALOA, MEXICO

[The rare monstrilloid copepod Monstrilla gibbosa Suarez-Morales & Palomares-Garcia, 1995 was described from a single specimen collected in a coastal system of southern Baja California. Following its description, this species had not been recorded again. During a short-term study on the planktonic copepods of the Urias estuary in Mazatlan, Sinaloa, Pacific coast of Mexico, a female specimen of M. gibbosa was collected. Monstrilla gibbosa is easily recognized by a combination of characters, including the presence of a peculiar keel-like ventral process on the anterior part of the cephalothorax, the structure of the fifth leg, details of the antennular armature, and the length of the ovigerous spines. However, the original description is incomplete according to the current, upgraded standards. This work provides a supplementary description of this species based on this second specimen. It includes additional illustrations of structures not previously described or depicted, such as the cuticular ornamentation, the complete armature of the antennule indicating all the elements, the structure of swimming legs 1-4, and intraspecific morphological variation. Although an interesting find, this new record of M. gibbosa represents a modest range extension in the Mexican Pacific., The rare monstrilloid copepod Monstrilla gibbosa Suarez-Morales & Palomares-Garcia, 1995 was described from a single specimen collected in a coastal system of southern Baja California. Following its description, this species had not been recorded again. During a short-term study on the planktonic copepods of the Urias estuary in Mazatlan, Sinaloa, Pacific coast of Mexico, a female specimen of M. gibbosa was collected. Monstrilla gibbosa is easily recognized by a combination of characters, including the presence of a peculiar keel-like ventral process on the anterior part of the cephalothorax, the structure of the fifth leg, details of the antennular armature, and the length of the ovigerous spines. However, the original description is incomplete according to the current, upgraded standards. This work provides a supplementary description of this species based on this second specimen. It includes additional illustrations of structures not previously described or depicted, such as the cuticular ornamentation, the complete armature of the antennule indicating all the elements, the structure of swimming legs 1-4, and intraspecific morphological variation. Although an interesting find, this new record of M. gibbosa represents a modest range extension in the Mexican Pacific.]

Cymbasoma tumorifrons (Copepoda: Monstrilloida): An Expanded Description Based on a New Collection from the Eastern Tropical Pacific

A female of the monstrilloid copepod species Cymbasoma tumorifrons (Isaac, 1975), previously known only from the Aegean Sea, was recorded in a bay of the Mexican tropical Pacific. The female of this rare species has not been recorded since its description more than 25 yr ago. To complement the brief original description, an expanded description and illustrations of this species are presented here based mainly on the Mexican specimen but considering also type material. Standards recently set for description of monstrilloid copepods were followed. Several characters such as chaetotaxy of legs 1-4, details of the antennular armature, cuticular ornamentation, and the fifth legs were overlooked in the original diagnosis and are described and analyzed here. This record supports an important range extension of the known distribution of this species from the Mediterranean Sea to the Mexican Pacific. It represents only the fourth record of a Cymbasoma species in the eastern Pacific.

A NEW SPECIES AND NEW GEOGRAPHIC RECORDS OF MONSTRILLA (COPEPODA: MONSTRILLOIDA) FROM THE PHILIPPINES

Abstract Specimens of a monstrilloid copepod of the genus Monstrilla collected (1908) by the U.S. Fisheries steamer Albatross in the Sulu Sea, west coast of Mindanao, Philippines, and deposited in the U.S. National Museum of Natural History were taxonomically restudied. Specimens were originally identified as females of Cymbasoma longispinosum Bourne, 1890, by C. B. Wilson. Reexamination revealed that besides a single female of C. longispinosum, three other specimens were present in the same vial. One of these was identified as a new species of Monstrilla and is described herein. The new species can be distinguished by a combination of characters but mainly by having very long antennules and a bilobed fifth leg with two long setae on each lobe. The other two individuals are females of M. elongata Suarez-Morales, 1994. This species has been previously recorded only from the Caribbean Sea. This record in the Philippines represents a significant range extension for this species. This one and the new species ...

The male ofCymbasoma quintanarooense(Suárez-Morales) (Copepoda, Monstrilloida) from the Caribbean with an identification key for the known males ofCymbasoma

Abstract The male of the monstrilloid copepod Cymbasoma quintanarooense Suarez-Morales, 1994 is described from several adult specimens collected in a reef lagoon on the southeast coast of the Yucatan Peninsula in the westernmost part of the Caribbean Basin. It is difficult to link male and female adult monstrilloids unless they are found as larvae in the same host. Males were assigned to Cymbasoma quintanarooense due to characteristic cephalic and genital protuberances that are also found in the female. The male closely resembles those of other species of Cymbasoma, but can be distinguished by a combination of characters including the structure of the genital lappets, the morphological details of the anal and preanal somites and the antennules, but mainly by the peculiar, bifid cephalic protuberance. A degree of intra-specific variation is recognized in the P2 setation pattern. A key for the identification of males of the 14 known species of Cymbasoma in which they have been recognized is presented. Comme...

A New Species and New Geographic Records of Monstrilla (Copepoda: Monstrilloida) from the Philippines

Specimens of a monstrilloid copepod of the genus Monstrilla collected (1908) by the U.S. Fisheries steamer Albatross in the Sulu Sea, west coast of Mindanao, Philippines, and deposited in the U.S. National Museum of Natural History were taxonomically restudied. Specimens were originally identified as females of Cymbasoma longispinosum Bourne, 1890, by C. B. Wilson. Reexamination revealed that besides a single female of C. longispinosum, three other specimens were present in the same vial. One of these was identified as a new species of Monstrilla and is described herein. The new species can be distinguished by a combination of characters but mainly by having very long antennules and a bilobed fifth leg with two long setae on each lobe. The other two individuals are females of M. elongata Suárez-Morales, 1994. This species has been previously recorded only from the Caribbean Sea. This record in the Philippines represents a significant range extension for this species. This one and the new species represent an interesting addition to the Asiatic monstrilloid fauna. Regional records of Monstrilla in the Far East are also presented herein. The Philippines and east Indonesia seem to be the most speciose areas for this genus in the entire region.