Two new records of dromiid crabs (Brachyura, Dromiidae, Dromiinae) from Taiwan, with notes on the taxonomy of Stimdromia McLay, 1993 and Epigodromia McLay, 1993

To evaluate whether ontogenetic development over the grow-out culture period can cause geographical plasticity of carapace shape in a certain region, geometric morphometric analysis was used, in this study, to determine the ontogenetic changes in the carapace morphology of Chinese mitten crabs (Eriocheir sinensis) originating from Yangcheng Lake, China, during a year of growth from coin-sized juveniles to market-sized adults. The morphological differences in the carapace throughout the year of culture were characterized using a 35-landmark point system. We used principal component analysis and linear discriminant analysis to determine morphological variation using thin-plate spline analysis and mesh deformation. During the growth process, the changes in the carapace were mainly concentrated in the third and fourth anterolateral teeth and on the M-shaped pattern. During the growth of male and female crabs throughout the year, the shape of the carapace changed considerably over the first six months. Afterwards, the shape of the carapace began to stabilize and could not be differentiated through discriminant analysis. This study is the first to use geometric morphometrics to analyze the ontogenetic changes in the carapace shape of E. sinensis crabs native to Yangcheng Lake. The results demonstrate that it takes a long time for the carapace morphology of native crabs to stabilize.

Fortipalpa Kasparyan & Ruíz-Cancino, 2007 originally accommodates only its type species, F. yucatanica Kasparyan & Ruíz-Cancino, 2007. The genus can be distinguished from all other Neotropical Cryptini by having mandible with ventral tooth subequal to slightly longer than dorsal tooth; propodeum anteriorly smooth, posteriorly with transverse striation; T1 long and slender, without anterolateral tooth; and ovipositor moderately long and straight, with ventral valve without a lobe covering dorsal valve. The genus is revised, and the following new species are proposed, described, and illustrated: F. exelysae sp. nov., F. frida sp. nov., F. heredia sp. nov., F. panamensis sp. nov., F. pichincha sp. nov., F. sacha sp. nov., and F. shakira sp. nov. The male of F. exelysae sp. nov., the first for the genus, is also described and illustrated; other males remain unknown. The type species is redescribed and illustrated, including pictures of the paratype and a new record to Trinidad. Figures, distribution maps and a taxonomic key are provided for all valid species.

Dalatomon gen. nov. Dang et Ho Diagnosis: crab is small in size, the length (l) under 30 mm, carapace trapezoid form, flat, upper surface smooth. Ischium maxilliped rectangular, merus almost rectangular, exopod long, reaching to 1/3 merus external margin. Male terminal segment of abdomen equilateral triangular, low with round top, lateral border straight, moderately longer than VI segment. GO1 terminal segment in male with dorsal, broad semicircular fold, extending to 2/3 length of this segment. Etymology: this genus name is derived from its type locality at Dalat (Lamdong province, west highland of Vietnam), in combination with the genus name Potamon. The gender is neuter. Type species: Dalatomon soni sp. nov. Dalatomon soni sp. nov. Dang et Ho Holotype: 1 male; Allotype, 1 female, collected from the stream at Dalat city (Lamdong province), Vietnam. Coll. 3 July, 2005; Paratype: 2 males, collected from Dalat city (Lamdong province). Coll 3 July, 2005, deposited in the Zoological Museum, Institute of Ecology and Biological resources, Hanoi-Vietnam. Diagnosis: crab is small in size, carapace largely transverse trapezoid, flat, upper surface smooth. Epibranchial tooth small. Anterolateral tooth not developed. Frontal margin moderately concave, Antero-lateral angle rounded, lateral margin oblique. Postfrontal, postorbital cristae cleared, undulated down, reaching to the basis of the epibranchian tooth. Postfrontal and postorbital bilobed swollen. Semilunar, H-shaped grooves distinct. Ischium maxilliped rectangular with groove in middle, exopod straigth, reaching to 1/3 merus external margin. Merus rectangular, flagella long reaching over merus upper margin. Male terminal segment of abdomen equilateral triangular, low with round top, lateral border straight, longer than VI segment. Subterminal segment of GO1 in male with basal part narrowly elongated. Terminal segment with dorsal, broad semicircular fold, located in the first half part, extending to 2/3 of this segment. Distal part of terminal segment cylinder-shaped, curved down tip truncate with upper distal angle produced as sharp, small, transparent projection. G2 long, slender, distal segment shorter than basal segment. Ambulatory legs slender, long. Remarks: Dalatomon soni sp. nov. is firstly found in Dalat city (Lamdong province), southern Vietnam. This species distributed in streams of highland mountainous areas but with small quantities. This new species is closely related to others species belonging to genera Laevimon, Donopotamon, Thaipotamon, Pudaengon, Rathbulamon, Phaibulamon, Pilosamon that are found in the Catba island (northern Vietnam) and in the basin of the Mekong river of southern Vietnam, Laos and Thailand. These species has the same characteristics such as terminal segment in GO1 of male with dorsal, broad semicircular fold but this new species differs from others by small size of carapace, the location of semicircular fold, the form of distal part of terminal segment and several different features as well. Table 1 Comparison of principal characteristics of Dalatomon gen. nov. with Donopotamon Dang et Ho 2005 and Laevimon Yeo et Ng., 2005 Characteristics of male Dalatomon Donopotamon Laevimon Size of carapace Small, the length less than 30 mm Big, the length more than 40 mm, even to 70 mm. Big, the length more than 40 mm. Carapace form Largely transverse trapezoid, flat, upper surface smooth. Largely transverse trapezoid, flat, upper surface smooth Anterolateral region rugose and granulose. Carapace distinctly transverse, high; dorsal surface strong convex longitudinally and transversely; smooth. Postorbital cristae Not sharp moderately oblique. Slightly sharp, horizontally straight. Uncleared. GO1 Subterminal segment with basal elongated. Terminal segment long 1/2 times length of subterminal segment, distal part curved down. Terminal segent with dorsal, broad semicircular fold, located in the first half part, extending to 2/3 of this segment. Terminal segment cylinder-shaped, tip truncate with upper distal angle produced as sharp, small, transparent projection. Subterminal segment with basal large, distal part narrow, neck-like. Terminal segment with dorsal, broad semicircular fold, occupying almost completely half distal part of this segment, establishing dove-head in shape. Subterminal segment with basal slender. Terminal segment short, about 1/3 times of subterminal segment. Terminal segment subcylindrical; tip truncate with inner distal angle produced as sharp, narrow projection. Hump-like, in proximal part, distinctly shorter than half length of terminal segment. Third maxilliped Ischium and merus rectangualar; exopod straight, reaching to 1/3 merus external margin. Flagellum long, reaching over merus upper margin; but shorter than merus width. Ischium rectangular; merus squarish; exopod straight, reaching to 1/3 merus external margin. Flagellum long, reaching over merus upper margin. Ischium broadly rectangular; merus squarish; upper angles rounded. Flagellum long, subequal to merus width. VII segment of the abdomen Equilateral triangular, low with round top, lateral border straight. Triangular; lateral border concave. Narrowly triangular; lateral border cocave at middle.

The Australian/Pacific wolf spider genus Diahogna Roewer, 1960 is revised with D. martensii (Karsch, 1878) as type species. In addition to D. martensii, of which the male is illustrated for the first time, the genus includes a further three species, D. exculta (L. Koch 1876), n. comb., D. hildegardae n. sp., and D. pisauroides n. sp. The presence of a basoembolic apophysis on the male pedipalp places Diahogna in an unnamed Australasian/Pacific subfamily of wolf spiders that also includes Anoteropsis L. Koch, 1878, Artoria Thorell, 1877, Notocosa Vink, 2003, and Tetralycosa Roewer, 1960. Diahogna differs from these mainly in the presence of a distinct apical extension of the tegulum on the male pedipalp. Somatic characters of Diahogna that are peculiar within the Lycosidae include eye arrangement, carapace shape, and body coloration which superficially resemble that of fishing spiders (Pisauridae). Lycosa neptunus (Rainbow, 1896) and Lycosa spinipes (Rainbow, 1896), both only known from the holotypes collected near Sydney, Australia, have been previously associated with D. martensii and D. exculta. As these types are immature specimens in faded condition, accurate species identification is impossible and both species are considered nomina dubia. All species of Diahogna are known from wet habitats, such as the margins of rivers, creeks, dams, marshes and swamps.

The Neotropical Distictus Townes, 1966 is diagnosed, redescribed and its species revised. A neotype is designated for the type species, D. tibialis (Brullé, 1846). The genus is characterized mainly by having the body subcylindric; clypeal margin with median tooth; areolet medium-sized, pentagonal, with crossvein 3r-m distinct; first metasomal tergite short and stout, with anterolateral tooth. Distictus aurantium Santos & Aguiar, 2008 is shown to lack some of these character states and is transferred to Mallochia Viereck, 1912. A total of 12 valid species are recognized, ten of which are new: D. apaensis sp. nov., D. ardens sp. nov., D. asterios sp. nov., D. ateles sp. nov., D. caligaris sp. nov., D. commatus sp. nov., D. daelus sp. nov., D. notabilis sp. nov., D. paratibialis sp. nov. and D. terrosus sp. nov. Other valid species are D. tibialis and D. mexicanus Kasparyan & Ruíz-Cancino, 2005. All species are described and illustrated. New distribution records, maps and separate keys for females and males of the species are provided.

Cytheridellawhitmani Martens, sp. nov. is described from lakes on Cape Cod (MA, USA). The species differs from its congeners mainly by the shape of the female carapace and by the morphology of the hemipenis, especially of the distal lobe and the copulatory process. The literature on the genus is reviewed and the synonymy of the fossil Cytheridellaboldii Purper, 1974 with the type species C.ilosvayi Daday, 1905, both described from South America, is confirmed. The status of Cytheridellaamericana (Furtos, 1936) is reverted to that of "uncertain species". Beside the type species and the new species, the genus currently includes only three further species from Africa: C.monodi Klie, 1936, C.damasi Klie, 1944 (with synonym C.chariessa Rome, 1977), and C.tepida Victor, 1987. The morphology of the new species is discussed in comparison with the congeneric species, especially regarding the valve ornamentation, the structure and function of the third thoracopod, the hemipenis and the caudal ramus. It is suggested that C.whitmani is a recent invasive species in the lakes of the Cape Cod peninsula. Its occurrence at northern latitudes is unexpected, as its congeneric species are consistently (sub-) tropical.

Embryonic, Larval, and Post-Larval Development in the Symbiotic Clam Codakia orbicularis (Bivalvia: Lucinidae)

Species with large eggs and nonfeeding larvae have evolved many times from ancestors with smaller eggs and feeding larvae in numerous groups of aquatic invertebrates and amphibians. This change in reproductive allocation and larval form is often accompanied by dramatic changes in development. Little is known of this transformation because the intermediate form (a facultatively feeding larva) is rare. Knowledge of facultatively feeding larvae may help explain the conditions under which nonfeeding larvae evolve. Two hypotheses concerning the evolutionary loss of larval feeding are as follows: (1) large eggs evolve before modifications in larval development, and (2) the intermediate form (facultatively feeding larva) is evolutionarily short-lived. I show that larvae of a heart urchin, Brisaster latifrons, are capable of feeding but do not require food to complete larval development. Food for larvae appears to have little effect on larval growth and development. The development, form, and suspension feeding mechanism of these larvae are similar to those of obligate-feeding larvae of other echinoids. Feeding rates of Brisaster larvae are similar to cooccurring, obligate-feeding echinoid larvae but are low relative to the large size of Brisaster larvae. The comparison shows that in Brisaster large egg size, independence from larval food, and relatively low feeding rate have evolved before the heterochronies and modified developmental mechanisms common in nonfeeding echinoid larvae. If it is general, the result suggests that hypotheses concerning the origin of nonfeeding larval development should be based on ecological factors that affect natural selection for large eggs, rather than on the evolution of heterochronies and developmental novelties in particular clades. I also discuss alternative hypotheses concerning the evolutionary persistence of facultative larval feeding as a reproductive strategy. These hypotheses could be tested against a phylogenetic hypothesis.

Egg quality, larval growth and phenotypic plasticity in a forcipulate seastar

Egg production, hatching rates, and abbreviated larval development of Campylonotus vagans Bate, 1888 (Crustacea: Decapoda: Caridea), in subantarctic waters

Planktotrophic larvae of marine invertebrates develop and grow by utilizing a com- bination of endogenous materials contained in the egg and exogenous food consumed during development. In general, larger eggs contain more reserves for morphogenesis and metabolism than smaller eggs. Interspecific comparisons among planktotrophic echinoderms have generally found that increased maternal provisioning decreases the length of development in the plankton, leading to the widely held idea that large eggs are likely to be selectively favored in low-food or high-mortality environments. Despite long interest in these patterns, however, few studies have examined how exogenous and endogenous supplies interactively affect larval development in phylogenetically controlled and environmentally relevant contexts. We investigated the direct and interactive effects of both endogenous egg materials and exogenous food supply on larval performance of 3 closely related tropical sea urchin species (Echinometra spp.). We found that egg size was positively correlated with egg energy among these 3 species, and that larvae of species with larger (and more energy-rich) eggs developed more rapidly than those from smaller (and lower-energy) eggs. Likewise, across species, larvae fed higher rations grew more rapidly than those fed less. Length of development was most strongly affected by food level in the species with the smallest eggs. Compared to the lowest food treatment, satiating levels shortened development by 9, 7, and 4 d for E. vanbrunti, E. lucunter, and E. viridis, respectively (listed in order of increas- ing egg energy). Our study supports the hypothesis that the growth and development of larvae are more strongly affected by exogenous food availability when they develop from lower-energy eggs than when larvae develop from energy-rich eggs.

Although inter- and intraspecific variation in egg size among amphibians has been well documented, the relationship between egg size and fitness remains unclear. Recent attempts to correlate egg size intraspecifically with larval developmental patterns have been equivocal. In this study the development of larvae derived from large eggs and small eggs, from a single population in Maryland were compared under a range of food levels and larval population densities. Both food level and density had significant effects on the length of the larval period and size at metamorphosis. However, the response among larvae derived from different egg sizes was not additive. At low densities and high food levels, larvae from small eggs had longer larval periods and a larger size at metamorphosis than larvae derived from large eggs. In contrast, at high densities larvae from small eggs had longer developmental periods but were smaller at metamorphosis than larvae from large eggs. In addition, larvae from small eggs were more sensitive to density irrespective of food level. These results suggest that optimal egg size is correlated with environmental factors, which may explain the maintenance of both geographic and within population variation in egg size commonly observed in amphibians.

Several decapod groups independently colonized freshwater and terrestrial habitats and became independent from the sea. These invasions were accompanied by analogous reproductive and developmental traits such as large eggs and an abbreviated, lecithotrophic development. Here, we present the first empirical study on the evolution of reproductive and developmental traits that accompany the invasion of land by crabs. As crucial steps in the colonization, we identify the transitions of the larval nursery, first, from the marine plankton into landlocked-brackish nurseries and, second, into fresh water. During these invasions, the early life-cycle stages were facing new ecological conditions and selective agents. We test hypotheses on the evolution of egg size and the mode of development in relation to the larval ecology of recent species and draw conclusions on their evolutionary past. As a model we focus on the genus Sesarma, that colonized Jamaica relatively recently and comprises species with a larval development in marine, brackish and freshwater habitats. In addition, we compare representatives of the crab genera Armases, Sesarma and Uca that invaded brackish-nursery habitats independently. The analysis reveals that in each genus the transition from marine to brackish nurseries resulted in fewer and larger eggs, an abbreviated development and higher endotrophic potential of larvae, and a wider tolerance to physicochemical stress (salinity). Size at metamorphosis, however, did not change in brackish species, suggesting that it is constrained. Within the Sesarma-lineage, egg size increases considerably from marine to freshwater species. The duration of embryonic development, the size and endotrophic potential of larvae are positively correlated, but the duration of the larval phase is negatively correlated with egg size. Hypotheses suggesting that large eggs evolved as a response to limited food or intense predation are inadequate to explain the initial egg-size increase in brackish species. We suggest that the specific abiotic environment of the brackish nurseries ultimately selected for increased egg size. These particular larval nurseries of brackish species of Armases, Sesarma and Uca are nutrient rich but ephemeral habitats with unfavourable physicochemical conditions, which strongly favour a swift larval phase and possibly large body size and higher salinity-stress resistance of larvae. The reason for the further and substantial increase in egg size in freshwater species remains unknown. The ‘food-limitation’ hypothesis derived from laboratory experiments, however, is inadequate to explain this increase. Our results support general life-history hypotheses (‘safe harbour’ hypothesis) that predict the evolution of large eggs if post-embryonic stages face high risk of mortality, but not the predicted positive relationship between egg size and instantaneous egg stage mortality. On the contrary, we find a negative relationship, suggesting that larger eggs are a ‘safer harbour’ than smaller eggs. We outline a scenario for the invasion of land by crabs and propose a two-step model: as a first step, an instant shift of the larval development from offshore into landlocked-brackish nurseries, and, as a second step, from there into freshwater nurseries.

Several decapod groups independently colonized freshwater and terrestrial habitats and became independent from the sea. These invasions were accompanied by analogous reproductive and developmental traits such as large eggs and an abbreviated, lecithotrophic development. Here, we present the first empirical study on the evolution of reproductive and developmental traits that accompany the invasion of land by crabs. As crucial steps in the colonization, we identify the transitions of the larval nursery, first, from the marine plankton into landlocked‐brackish nurseries and, second, into fresh water. During these invasions, the early life‐cycle stages were facing new ecological conditions and selective agents. We test hypotheses on the evolution of egg size and the mode of development in relation to the larval ecology of recent species and draw conclusions on their evolutionary past. As a model we focus on the genus Sesarma, that colonized Jamaica relatively recently and comprises species with a larval development in marine, brackish and freshwater habitats. In addition, we compare representatives of the crab genera Armases, Sesarma and Uca that invaded brackish‐nursery habitats independently. The analysis reveals that in each genus the transition from marine to brackish nurseries resulted in fewer and larger eggs, an abbreviated development and higher endotrophic potential of larvae, and a wider tolerance to physicochemical stress (salinity). Size at metamorphosis, however, did not change in brackish species, suggesting that it is constrained. Within the Sesarma‐lineage, egg size increases considerably from marine to freshwater species. The duration of embryonic development, the size and endotrophic potential of larvae are positively correlated, but the duration of the larval phase is negatively correlated with egg size. Hypotheses suggesting that large eggs evolved as a response to limited food or intense predation are inadequate to explain the initial egg‐size increase in brackish species. We suggest that the specific abiotic environment of the brackish nurseries ultimately selected for increased egg size. These particular larval nurseries of brackish species of Armases, Sesarma and Uca are nutrient rich but ephemeral habitats with unfavourable physicochemical conditions, which strongly favour a swift larval phase and possibly large body size and higher salinity‐stress resistance of larvae. The reason for the further and substantial increase in egg size in freshwater species remains unknown. The ‘food‐limitation’ hypothesis derived from laboratory experiments, however, is inadequate to explain this increase. Our results support general life‐history hypotheses (‘safe harbour’ hypothesis) that predict the evolution of large eggs if post‐embryonic stages face high risk of mortality, but not the predicted positive relationship between egg size and instantaneous egg stage mortality. On the contrary, we find a negative relationship, suggesting that larger eggs are a ‘safer harbour’ than smaller eggs. We outline a scenario for the invasion of land by crabs and propose a two‐step model: as a first step, an instant shift of the larval development from offshore into landlocked‐brackish nurseries, and, as a second step, from there into freshwater nurseries.

The production of small numbers of large eggs among the standard-sized eggs of Trichuris trichiura is well known. Large eggs have also been observed in Trichuris muris, but they have not been studied previously. This paper compares the characteristics of the large eggs (LEs, ≥74.5μm long) and standard-sized eggs (SEs, <74.5μm long) in cultures of T. muris. Among 112,554 cultured eggs, LEs occurred at very low frequency (0.03%, i.e., about three large eggs per 10(4) cultured eggs). Embryonated eggs represented 93.72% of SEs, but only 25.00% of LEs were embryonated. Embryonated LEs and SEs contained fully matured larvae. An atypical category of unembryonated egg, which contained an incompletely developed larva, an abnormal larva, or granular components, was common among the LEs. However, similar atypical unembryonated SEs were rarely observed. These observations suggest that the LEs that occur very infrequently in T. muris result from an abnormality of embryonation (larval development).