Burrow morphology of the echiuran worm Maxmuelleria lankesteri (Echiura: Bonelliidae), and a brief review of burrow structure and related ecology of the Echiura

The burrow morphology of the echiuran worm Maxmuelleria lankesteri (Herdman) was investigated in situ using a resin casting technique. Work was carried out in Lochs Sween and Creran on the west coast of Scotland in predominantly fine mud sediments. Burrow casts typically had only 1 opening, although there is evidence to suggest that a second opening may exist. In 58% of burrows, the opening, which was small and funnel-shaped, was associated with a surface mound reaching up to 20 cm in height. The tunnel below the burrow opening, the ‘neck’, was narrow and circular in transverse section with a smooth wall, possibly due to the action of the mucus-laden proboscis which emerges during feeding. The maximum burrow depth recorded was 80 cm and tunnel orientation became more horizontal with increasing depth. In some larger burrows, the tunnel began to orientate upwards towards its end. Below the neck, the tunnel was much wider but had a sub-circular transverse section. The burrows had distinct striations on the walls of lower tunnels, possibly caused by movements of the animal within. In some cases, a community of symbiotic organisms had developed, including polychaetes and 2 species of bivalve, Mysella bidentata (Montagu) and Saxicavella jeffresii Winckworth. Evidence of burrow modification by the crustacean Jaxea nocturna Nardo was noted and gobies, including Gobius niger Linnaeus, were also responsible for some alterations to the upper burrow around the opening. Evidence suggested that burrows were permanent structures which changed little in position.     

The juvenile stages of Parastacus brasiliensis (von Martens, 1869) (Crustacea,Decapoda, Parastacidae)

The family Parastacidae consists of the freshwater crustaceans popularly known as crayfishes or crawfishes. Only the genus Parastacus occurs in Brazil, with P. brasiliensis (von Martens, 1869) endemic to the state of Rio Grande do Sul in southern Brazil. Parastacids have direct development, ecloding as juveniles. In laboratory‐reared specimens, juvenile I stage is similar in morphology to the adult, with no setae on most appendages, absence of uropods and presence of a hook on the dactyl of pereiopods 4 and 5. The juvenile II retains juvenile I characteristics but has more setae, which are more varied in morphology. The juvenile III possesses setae as the adults, fully formed uropods and the hooks on pereiopods 4 and 5 are substituted by an apical rectilinear dactylus.     

The functional morphology of the feeding and grooming appendages of Ebalia tuberosa (Pennant) (Crustacea: Decapoda: Leucosiidae)

Summary

Ebalia tuberosa feeds mainly on small invertebrates but will also scavenge. The morphology of the feeding and grooming appendages is described paying particular attention to the structure and distribution of the setae. The movements of the various appendages during feeding are analysed. The mouthparts function in manipulating, grasping and cutting the food; in forming setal screens which prevent food from falling out of the mouth region; in creating water currents to waft away rejected material; and in cleaning each other. Setal structure is correlated with function. Those appendages which manipulate the food are armed with cuspidate and serrate setae while those which hold the food string steady during cutting carry plumodenticulate setae. Plumodenticulate and serrulate setae of various types make up two buccal setal screens, one transverse and the other longitudinal. The rejection current is generated by the flagella of the exopodites of the 1st and 2nd maxillipeds which bear long plumose setae. The main cleaning appendages are the 3rd maxillipeds whose distal segments bear serrate setae. In addition, various appendages bear fields of plumodenticulate setae which brush and clean adjacent surfaces during the normal feeding movements of the mouthparts.     

Setal diversity,trophic modes and functional morphology of feeding appendages of two callianassid shrimps,Callichirus major and Sergio mirim (Decapoda: Thalassinidea: Callianassidae)

In the present study we investigate the trophic behaviour, stomach content and morphology of the feeding appendages, with emphasis on setae, of two callianassids; a generalist feeder, Callichirus major (Say, 1818) and a strict deposit feeder, Sergio mirim (Rodrigues, 1971). Of the 87 setal types described, only 5% were common to both species. Setal types were clustered in four main categories; plumed, serrate, plumodenticulate and simple. Callichirus major has higher setal diversity than S. mirim. Relative to the amount of setal types present in each species, C. major has a higher ratio of serrate to plumodenticulate setal types and similar percentages of plumed and simple setae. Examining the setae and spatial position of the segments of the feeding appendages, it is possible to infer that the main function of the dactyli, propodi and basal endites is to brush particles, while the meri, ischia and coxal endites retain sediment. The setal diversity found on the feeding appendages reflected the diverse trophic strategies of the callianassid species studied. Exclusive deposit feeders, e.g. S. mirim, appear to have fewer setal types than generalist feeders, e.g. C. major. Apparently, the higher ratio of serrate to plumodenticulate setal types in Callianassidae depends more on the necessity to triturate particles prior to ingestion than on the trophic mechanism used by the species.     

Description of a new Tetranychus (Acarina,Prostigmata: Tetranychidae) pest of Musa from French Guiana

A new species of tetranychid mite, genus Tetranychus Dufour, 1832, is described and illustrated herein from neotropical area. Tetranychus musae sp. nov. (Acari, Prostigmata: Tetranychidae) differs from other species in the genus by the combination between the arrangement of leg setae on females tarsus I and the shape of the aedeagus. Tarsus I bears one tactile setae proximal to proximal duplex setae and three tactiles in line or almost in line with proximal duplex setae. The aedeagus knob consists of an acute posterior projection bent ventrally and a larger anterior rounded projection directed anterodorsally. T. musae specimens were collected in French Guiana where they appeared to be a pest of Musa sp. A key to adults of neotropical species of the genus Tetranychus feeding on banana is provided.     

Microscopic morphology of the antennule and antenna of the marine isopod Cirolana harfordi

ABSTRACT

The use of scanning electron microscopy on the cuticle outgrowths called setae (that contain sensilla) in crustaceans is useful for, understanding how crustacean species sense their environment and for taxonomic studies. So far, most of the setal morphology studies have been performed on decapod crustaceans such as lobsters and shrimps and there has been a comparative lack of such research on marine isopods, from which terrestrial isopods such as woodlice or slaters have evolved. In the current study, electron microscopy was used to study the antennal setae of the marine isopod Cirolana harfordi using magnification powers of up to 40, 000. C. harfordi displayed a number of setal types including setae that had a sub-terminal pore that contained a cupule-shaped structure and plumose setae which are pennate in structure and have two rows of setules along the setal shaft in a fashion analogous to a palm leaf. These plumose setae may be useful to the animal in detecting water currents. Differences in the structure and placement of setae on the antennae of C. harfordi as compared to two other marine isopods, Bathynomus pelor and Natatolana borealis (that have had a comprehensive study of antennae setal morphology performed on them in previous studies) indicate that scanning electron microscopy of isopod setae may be useful in taxonomic studies of isopods.     

Temporal changes in burrow structure of the thalassinidean ghost shrimps Trypaea australiensis and Biffarius arenosus

The thalassinidean ghost shrimps Trypaea australiensis and Biffarius arenosus are dominant burrowing macroinvertebrates of soft‐sediment habitats in Western Port, Victoria, Australia. Burrow structure has been described for both species but little is known about how the burrows change over time. This study used resin casting to investigate temporal variation by making burrow casts each month over a 12‐month period. It was found that the overall burrow morphology of both T. australiensis and B. arenosus was consistent over time, but in the warmer months (summer and spring), both species constructed burrows that were deeper and of greater volume than burrows constructed in winter and autumn. Possible reasons for this variation are discussed.     

Description of two new species of Zosime (Copepoda: Harpacticoida: Zosimeidae), including remarks on its phylogeny and distribution on the Great Meteor Seamount plateau (North-east Atlantic Ocean)

Quantitative sampling during the POS397 GroMet expedition in 2010 allowed analysis of the community structure of Zosimeidae on the Great Meteor Seamount (GMS) plateau. Twelve species of Zosime Boeck, 1873 were identified; 11 were recorded in the middle, nine in the northern, and 10 in the southern region. Similarity and diversity analyses showed no differences in community structure between these regions. The community seemed unaffected by geographical features; similarities between regions could reflect the uniform sediment structure and the complex water current system. Zosime can be characterised as monophyletic, due to the apomorphic one-segmented endopod of the mandible, armed with at most four setae. Two new species are described. Zosime carsteni sp. nov. (incrassata group) is defined by blunt spinules on the outer spines of exopods 1–3 of pereiopods 2–4 and the spinose nature of the innermost distal element of endopod 3 of pereiopods 1–4. Zosime eliasi sp. nov. (typica group) is defined by a flexible outer seta on the maxillipedal endopod. As both species bear an eight-segmented antennule (most plesiomorphic condition known so far), the recently erected anneae group is included into the typica group. An updated key of Zosime at the species level is given.

www.zoobank.org/urn:lsid:zoobank.org:pub:0BA28922-C575-4AAD-AD64-FDDBA22C34CC     

Poecilostomatoid Copepods from an Intertidal Mud Flat in the Yellow Sea

Thirteen new species and one new genus of poecilostomatoid copepods are described from intertidal mud flats in the central west coast of the Korean Peninsula facing the Yellow Sea. Nine species are found in association with invertebrates: Hemicyclops ventriplanus n. sp. from the decapod crustacean Upogebia major (De Haan); Clausia lobata n. sp. from the polychaete Marphysa sanguinea (Montagu); Presynaptiphilus minutus n. sp. from the ophiuroid Amphiura sinicola (Matsumoto); Synaptiphilus longicaudus n. sp. and Enterophilus cercomegalus n. gen. et n. sp. from the holothurian Protankyra bidentata (Woodward and Barrett); Goidelia pelliviva n. sp. from an echiuroid Thalassema sp.; Lichomolgus bullatus n. sp. from the bivalve Striarca (Didimacar) tenebrica (Reeve); Critomolgus nudus n. sp. from the pennatulacean Virgularia gustaviana (Herklots); and Notoxynus tertius n. sp. from the sea anemone Cerianthus filiformis Carlgren. The other four species are found in stagnant water on the mud flat: Kelleria vaga n. sp., Macrochiron anormalum n. sp., Pseudomacrochiron urostenum n. sp. and Pseudanthessius dentatus n. sp.     

Chinese psyllids in the genus Cacopsylla (Hemiptera: Sternorrhyncha: Psylloidea) associated with Spiraea (Rosaceae)

The Chinese Cacopsylla species associated with Spiraea are revised. Three new species (Cacopsylla falcata sp. nov., C. nocturna sp. nov. and C. qilianensis sp. nov.) are described, and two [C. hyalinonemae Li and Yang, 1989 and C. spiraeicola (Li, 2011) comb. nov.] are redescribed. A new combination is also proposed for Cacopsylla tetrotaenialis (Li and Yang, 1989) comb. nov. Among the five species, C. falcata and C. qilianensis are affirmed to develop on Spiraea, as fifth instar immatures were found. The host plants of the other species remain uncertain. Based on morphological grounds, it is suggested that C. falcata and C. nocturna are closely related, but that the five species associated with Spiraea do not constitute a monophyletic group.     

The larval development of the spider crab Rochinia gracilipes (Crustacea: Majoidea: Epialtidae: Pisinae) reared in the laboratory

The larval development of the spider crab Rochinia gracilipes Milne-Edwards, 1875 (Crustacea: Decapoda: Brachyura: Majoidea: Epialtidae: Pisinae) is described and illustrated from laboratory-reared larvae. Development consisted of two zoeal stages and one megalopa, following the typical pattern in Majoidea. Zoea I of R. gracilipes, R. debilis and R. carpenteri differed in lengths of the rostral spine of the carapace, in the number of setae and aesthetascs of several head appendages (exopods of antennules, endopods of maxillules, and endopods and scaphognathites of maxillae) and in the length of posterolateral processes of abdominal somites; lateral carapace spines were present only in R. carpenteri and pleopod buds only in R. debilis. Megalopae of Rochinia gracilipes and R. carpenteri differed in several notable characters: a dorsal spine and long rostrum of the carapace, as well as spines in coxa and ischium of pereiopods, appeared only in R. carpenteri, and podobranchiae of the 3rd maxilliped appeared only in R. gracilipes; they also differed in setation of abdomen and pleopods. The comparison of the available information on Pisinae larval development suggested that larval morphology would not help to accurately understand the phylogenetic relationships of this subfamily of spider crabs.     

Thalassarachna and Halacarellus (Halacaridae: Acari): two separate genera

During the last half century, the generic names Halacarellus and Thalassarachna have been used in parallel. The author now proposes to regard them as two separate genera distinguished by the number of dorsal setae on tarsi I and II. Halacarellus s. str., with Halacarus balticus Lohmann as the type species, has three dorsal setae on both tarsi, whilst Thalassarachna s. str., with the type species Acarus basteri Johnston, has five or more dorsal setae on tarsus I and four or more on tarsus II. The number of setae on tarsi I and II is expected to be a valid generic character. Species of the genus Halacarellus s. str. are recorded from both the northern and southern hemispheres; the North Atlantic species are distinct from those in the southern oceans. Thalassarachna s. str. is known only from the North.     

Two new species of the commensal shrimp genus Periclimenaeus Borradaile, 1915, (Decapoda,Palaemonidae) from the Maldive Islands

Two new species of the commensal shrimp genus Periclimenaeus Borradaile, found in the waters of the Maldive Islands, Indian Ocean, are described and illustrated. P. tchesunovi sp. nov. is related to P. rastrifer Bruce. The former may be distinguished by its deeper rostrum, with dentition 6/1, the presence of supraorbital tubercles, and broad, spatulate fingers on the first pereiopods. P. zarenkovi sp. nov. closely resembles P. diplosomatis Bruce in the presence of minute denticulations on the dactylar cutting edge of the major second pereiopod, but differs from it by a deeper rostrum with 5 dorsal teeth, more robust chelae of the second pereiopods, and small dorsal telson spines.     

The mouthparts and feeding behaviour of two species of hermit crabs

Summary

The mouthparts of P. novae-zealandiae and S. setosus are similar in construction, but differ in details of setation. These differences are related to particular feeding habits. S. Setosus is a suspension filter feeder, the antennae being modified to form sieves which actively sweep plankton from the water. Setation of the maxillipeds is modified for cleaning the antennae. Both species are detritus feeders and this is the major source of food for P. novae-zealandiae, the maxillipeds here bearing numerous stout setae with dentate margins. Neither species readily feeds on large food and it is suggested that S. setosus is less well adapted to do so.     

Morphometry and chaetotaxy of the nymphs of Ectemnostega (Ectemnostegella) quechua (Bachmann 1961) (Insecta: Hemiptera: Heteroptera: Corixidae)

The egg and the five nymphal instars of Ectemnostega quechua are described and illustrated for the first time. The eggs of Ectemnostega have a short stalk, and the shape, size and chorionic structure differ among groups of species. The nymphal characters most useful in identifying instars I–V of Ectemnostega are: body length; number of rostrum sulcations; number of setae on inner surface of protibiotarsus; spines and setae, and spines on posteroventral surface of mesofemur and mesotibia, respectively; setae on posterodorsal surface of mesotibia and mesotarsus; spines and setae on anteroventral surface and setae on posterior surface of metatibia; swimming hairs on anteroventral and posterodorsal surfaces of metatarsus; and the grade of development of wing pads. The nymphs of E. quechua can be easily distinguished from other species of Ectemnostega by the number of spines and setae on the posteroventral surface of mesofemur.     

A new genus and species of leptostracan (Crustacea: Malacostraca: Phyllocarida) from Guana Island,British Virgin Islands,and a review of leptostracan genera

Saronebalia guanensis, a new genus and species of leptostracan, is described from material discovered in shallow subtidal waters of Guana Island, British Virgin Islands. The specimens were collected from light traps placed on sediment and by hand from the green alga Halimeda. Saronebalia differs from other leptostracans most notably in the morphology of the antennule and the eighth thoracic limb: the articles of the antennular flagellum are fused and bear dense clusters of setae, and the eighth thoracic limb is elongate. While its eyes, like those of Nebalia, are non-tuberculate, it shares the rostral spine, dentate process of antennular article 4, and serrate pleopodal protopods of Levinebalia and Paranebalia. Specimens of the new genus lack the setal row of the exopod of pleopod 1, a complex feature characteristic of Dahlella, Levinebalia, Nebalia and Paranebalia. A cladistic analysis of the 10 leptostracan genera, using 30 morphological characters from these features and others, also supports the status of Saronebalia as a new genus. Saronebalia represents the third leptostracan genus to be recorded from the Caribbean Sea.     

Expanding the taxonomic conundrum: Three new species of groundwater crustacean (Syncarida,Bathynellacea, Parabathynellidae) endemic to the Iberian Peninsula

Two new species of the genus Iberobathynella and one new species of the cosmopolitan genus Hexabathynella are described from the Iberian Peninsula. The three new species were found in the groundwater of caves and the gravelly bank of a river, two species in the north of Spain (Cantabria and Burgos) and one in the south (Sevilla). The two new species of the genus Iberobathynella present a unique combination of characters. These character combinations for the species from Cantabria are: thoracopod 8 female with wrinkled cuticle and two teeth; seven spines on the furca; nine spines on the sympod, three barbed and one plumose seta on the exopod and two barbed setae on the endopod of the uropod; maxilla with 0, 0 and 15 setae on the three segments, respectively; five teeth on the pars incisiva and six teeth on the pars molaris of the mandible and seven segments on the antennule. The combinations of characters for the species from Burgos are: antennule with seven segments; segment 5 of the antennule with one aesthetasc; mandible with four and five teeth on the pars incisiva and pars molaris respectively; maxillule with one seta on segment 1 and 14 setae on segment 3; segment 1 of the endopod of the thoracopod 1 with two setae; uropod with six spines on the sympod, four barbed setae and one plumose seta on the exopod and no setae on the endopod; furca with five spines and the thoracopod 8 female with wrinkled cuticle and two teeth. This last species has an exclusive character for the genus: the absence of setae on the endopod of the uropod. The new species of the genus Hexabathynella has six spines of similar length on the sympod of the uropod (in all other species within the genus the distal spine is longer than the others); the form of the antennal organ in the males is shown to be a new unique character for the genus; the maxilla has three and 13 setae on segments 2 and 3, respectively; the uropod has six spines on the sympod, three barbed setae on the exopod and two smooth setae on the endopod, the endopod is twice as long as the exopod and the shape of the female thoracopod 8 is unique.     

Revision of Stegosoladidus Barnard and Karaman, 1987 (Crustacea: Amphipoda: Stegocephalidae), redescription of two species and description of three new species

Stegosoladidus simplex (K. H. Barnard, 1930) and S. ingens (Chevreux, 1906) are both figured and redescribed. Three new species (Stegosoladidus antarcticus, S. complex and S. debroyeri) are described. The terminology used for classification of both setae and different setae arrangements is discussed, and the main types of setae are figured.