Gammarinema scyllae sp. n. and Monhystrium mangrovi sp. n. (Nematoda: Monhysteridae) from land crabs from New Caledonia

Two new species of nematodes associated with crabs are described from New Caledonia. Gammarinema scyllaesp. n. from the gill chambers of Scylla serrata (Forsskål) is characterised by 3–4 mm long body, small outer labial and cephalic sensilla, distinct ocelli, short straight spicules and sub-cylindrical tail. Monhystrium mangrovisp. n. from the gill chambers and body cavity of mangrove crab Neosarmatium sp. is characterised by 1–1.4 mm long body; outer labial sensilla longer than cephalic sensilla, amphid located at level with posterior stoma chamber, denticles in posterior stoma chamber and five pairs of genital papilla on tail. Phylogenetic relationships of two new species and other nematodes from the family Monhysteridae are analysed based on 18S and partial 28S rDNA sequences.

PENINGKATAN PRODUKTIVITAS TERNAK SAPI MELALUI INTRODUKSI HIJAUAN PAKAN TERNAK UNGGUL DI PULO NASI ACEH BESAR

ABSTRAKTernak sapi di Pulo Nasi Kabupaten Aceh Besar umumnya dipelihara seadanya, dibiarkan lepas sepanjang hari sehingga dapat menggangu usaha pertanian, jalan umum, dan masalah sosial. Permasalahan utamanya disebabkan keterbatasan tersedianya hijauan pakan ternak (HPT) dan perkandangan yang tidak memadai. Tujuan pengabdian ini adalah meningkatkan pengetahuan dan keterampilan peternak dalam penyediaan HPT berupa rumput unggul (odot dan lampung) dan manajemen pemeliharaan sapi. Metode pelaksanaan berupa: penyuluhan, pelatihan, dan pendampingan. Metode pengumpulan data dengan wawancara (kuesioner). Data dianalisis secara deskriptif kualitatif. Keberhasilan kegiatan pengabdian ini diukur kemampuan anggota kelompok peternak dalam menanam dan merawat HPT dan perbaikan tata laksana pemeliharaan sapi. Sasaran kegiatan adalah Kelompok Peternak Deudap Usaha Mandiri dan Beujaya Gampong di Desa Deudap Pulo Nasi Kabupaten Aceh Besar. Hasil pelaksanaan menunjukkan anggota peternak telah terampil melakukan penanaman dan pemeliharaan rumput odot dan lampung. Nilai ketercapaian materi adalah 86% dari 35 orang anggota kelompok peternak. Pemeliharaan rumput odot lebih mudah dan disukai ternak sapi. Dampak lainnya adalah kelompok peternak sepakat membuat kandang sapi komunal. Kendala yang ditemukan saat awal penanaman rumpot odot dan lampung berupa gangguan kepiting darat yang merusak tunas muda. Simpulan menunjukkan bahwa peternak telah berkomitmen untuk memelihara rumput dan mengandangkan sapinya. Kata kunci: pulo nasi aceh besar; sapi; rumpot odot; rumput lampung. ABSTRACTThe problem of cattle in Pulo Nasi, Kabupaten Aceh Besar, is generally maintained as it is without adequate management. Cows are left loose all day long so they can interfere with agricultural, pollute yard and public roads as well as social problems. This problem can occur due to the limited availability of forages and cow housing. The purpose of this service activity is to increase the knowledge and skills of farmer regarding the provision of forage to introduction (planting) of superior grass (odot and lampung) and cow rearing management. The implementation method was: counseling, training, and mentoring. The method of collecting data by interview (questionnaire). Data were analyzed descriptively qualitatively. The success of this service activity was measured by the ability of the farmer group members to plant and care for HPT and improve the management of cattle raising. The targets of the activity were two groups of farmers Deudap Usaha Mandiri and Beujaya Gampong in Deudap Village. The results showed that the members of the farmer were skilled at planting and maintaining odot and lampung grass. The value of material achievement was 86% of the 35 farmer group members. Maintenance of odot grass is easier and preferred by cattle. Another impact is that farmer groups agree to build a communal cow shed. The obstacle found at the beginning of planting odot and lampung clumps was disturbance of land crabs which damaged the young shoots. The conclusion shows that the farmer has committed to maintain the grass and house his cows. Keywords: pulo aceh; cattle; dwarf elephant grass; lampung grass; cattle farming management.

A morphological, phylogenetic and phylogeographic reappraisal of the land crabs Gecarcinus quadratus De Saussure, 1853, and G. lateralis Fréminville in Guérin, 1832 (Decapoda: Gecarcinidae). Are they different species?

Land crabs of the genus Gecarcinus are distributed along both versants of the American continent. At some point four species were recognized: G. lateralis, G. nobilii, G. quadratus, and G. ruricola. Taxonomically, several authors have tried to differentiate Gecarcinus lateralis from the Atlantic coast and G. quadratus from the Pacific coast. Because morphologic characters used showed high intra-population variability, identification were very difficult. Consequently, these two species have occasionally been considered synonyms. To establish the degree of genetic difference between them a molecular analysis was performed with both species, G. lateralis and G. quadratus, including Mexican Pacific and Atlantic specimens, using the mitochondrial COI and 16S genes. The maximum clade credibility and maximum likelihood trees showed two clades with high support values, one corresponding to the Gulf of Mexico population and the other one to the Pacific coast population, with a genetic distance of 6.1%. The within-clade average distance for the Atlantic populations (G. lateralis) was 1.1% and 0.2% for those of the Pacific coast (G. quadratus). This supports the status of G. quadratus as a valid species, not as a synonym of G. lateralis. The estimated time of divergence between both species ranged between 2.3 to 4.3 million years, coinciding with the proposed closure of the Isthmus of Panama. Morphologically, some populations show high variability in somatic characters, whereas sexual appendices of males of both species showed very little variation. Color in life, shape of sternite 3, and shape and degree of coverage of the abdomen of thoracic sternites, in both sexes, are traits that can be used to differentiate both species.

The role of anthropogenic disturbance and invasion of yellow crazy ant in a recent decline of land crab population

The yellow crazy ant, Anoplolepis gracilipes was first reported in Kenting National Park, Taiwan, in the 2000s, raising the concern of this invasive ant’s potential effects on the native land crab populations. We investigated the distribution and abundance of A. gracilipes and its adverse effect on the land crab populations at four land crab hotspots within the park. Our survey results indicated that A. gracilipes was widespread and abundant at three of the study sites (Hsiangchiaowan, Shadao, and Natural Spring), while the distribution was much more confined at the fourth site (Houwan). Land crab populations experienced a notable decline at all the study sites except Houwan, indicating an inverse relationship between the population of land crabs and distribution/abundance of A. gracilipes. Combining the results of visual observations, the decline of land crab populations can be attributed, at least partially, to direct attacks by A. gracilipes on land crabs in their natural habitat and during the breeding migration season. Generalized additive model showed that worker abundance of this ant is associated with human disturbance levels, suggesting that anthropogenic disturbance may have contributed to the decline in land crab populations via promoting the abundance of A. gracilipes.

Hemolymph supply to locomotor muscles of the ghost crab, Ocypode quadrata

Ghost crabs are the fastest and most aerobically fit of the land crabs. The exceptional locomotory capacity of these invertebrate athletes seemingly depends upon effective coupling between the cardiovascular system and skeletal muscles, but how these systems are integrated has not been well defined. In the current study, we investigated the relationship between aerobic muscle fibers within the skeletal muscles used to power running and the blood vessels supplying these muscles. We used histochemical staining techniques to identify aerobic versus glycolytic fibers and to characterize membrane invaginations within the aerobic fibers. We also determined how the diameters of these two fiber types scale as a function of body size, across two orders of magnitude. Vascular casts were made of the blood vessels perfusing these muscles and special attention was given to small, capillary-like vessels supplying the fibers. Finally, we injected fluorescent microspheres into the hearts of living crabs and tracked their deposition into different muscle regions to quantify relative hemolymph flow to metabolic fiber types. Collectively, these analyses demonstrate that ghost crab muscles are endowed with an extensive arterial hemolymph supply. Moreover, the hemolymph flow to aerobic fibers is significantly greater than to glycolytic fibers within the same muscles. Aerobic fibers are increasingly subdivided by membrane invaginations as crabs increase in size, keeping the diffusive distances relatively constant. These findings support a functional coupling between a well-developed circulatory system and metabolically active muscle fibers in these invertebrates.

Dietary preferences of brachyuran crabs from Taiwan for marine or terrestrial food sources: evidence based on fatty acid trophic markers

Background Trophic interactions are key processes, which determine the ecological function and performance of organisms. Many decapod crustaceans feed on plant material as a source for essential nutrients, e.g. polyunsaturated fatty acids. Strictly herbivorous feeding appears only occasionally in marine decapods but is common in land crabs. To verify food preferences and to establish trophic markers, we studied the lipid and fatty acid composition of the midgut glands of two marine crab species (Grapsus albolineatus and Percnon affine), one semi-terrestrial species (Orisarma intermedium, formerly Sesarmops intermedius), and one terrestrial species (Geothelphusa albogilva) from Taiwan. Results All species showed a wide span of total lipid levels ranging from 4 to 42% of the dry mass (%DM) in the marine P. affine and from 3 to 25%DM in the terrestrial G. albogilva. Triacylglycerols (TAG) were the major storage lipid compound. The fatty acids 16:0, 18:1(n-9), and 20:4(n-6) prevailed in all species. Essential fatty acids such as 20:4(n-6) originated from the diet. Terrestrial species also showed relatively high amounts of 18:2(n-6), which is a trophic marker for vascular plants. The fatty acid compositions of the four species allow to clearly distinguish between marine and terrestrial herbivorous feeding due to significantly different amounts of 16:0, 18:1(n-9), and 18:2(n-6). Conclusions Based on the fatty acid composition, marine/terrestrial herbivory indices were defined and compared with regard to their resolution and differentiating capacity. These indices can help to reveal trophic preferences of unexplored species, particularly in habitats of border regions like mangrove intertidal flats and estuaries.

Coastal road mortality of land crab during spawning migration

Land crabs are threatened by ocean sprawl even though they act as keystone consumers in coastal forest. Female land crabs must migrate to the sea annually to release larvae. However, they face the risk of road mortality which reduces ecological connectivity. We investigated the spawning migration rhythm and the roadkill of land crab. Migrating crabs and roadkilled crabs were recorded on coastal roads in South Korea from July 28 to August 27 in 2018. Female land crabs mainly released zoeae during spring tide. The number of roadkilled crabs also synchronized with migration peak. A majority (95%) of 739 roadkilled carcasses were female crabs. As a result, the female crabs accounted only 29.6% of the population which can lead to a population decline. The roadkill density was the highest in a residential area without cement guardrails. These results suggest the mitigation actions for land crab roadkill. Among them, prohibiting vehicular traffic between sunset and midnight during spring tides in the breeding season should increase the viability of the population.

Reproductive Biology of Land Crabs (Gecarcoidea lalandii) in Ly Son Island, Quang Ngai Province – Vietnam

The reproductive biology of the land crab Gecarcoidea lalandii was documented for the Ly Son Island, Quang Ngai Province, Vietnam. Approximately 30 crabs, collected every month in the 12-month period from August 2019 to July 2020, were analyzed gonadal development stages, sex ratio, spawning season, fecundity and size at first sexual maturity. Results showed that number of male and female crab in nature was not significantly different. Gonadal of the crab passed through five stages of maturation. The crab spawns continuously during the spawning season. In nature, the crab can mature whole year-round with a higher proportion from January to August and the peak maturation from June to July. The spawning season is of this species is only on the raining period from June to July. Length at first sexual maturity of the crab was 53.91 mm of carapace width for female and 50.39 mm male crab. The absolute fecundity varied in 473,000-820,000 eggs ind-1 and highly related to body weight. The current findings provide the scientific foundation for fishery resource management and artificial breeding of the land crab in Ly Son.

Influence of roadkill during breeding migration on the sex ratio of land crab (Sesarma haematoche)

Adult land crabs generally live on land while their larvae live in the sea. In the case of Sesarma haematoche, female crabs migrate from land to sea to release the larvae at the high tide of syzygy night. Artificial structures along coastal areas are being obstacles for the migration of land crabs and causing synchronized roadkills on coastal roads during breeding migration. In this research, we compared the sex ratios of crab populations in coastal areas with coastal roads and uninhabited island areas with no road. The proportion of females in inland habitats with coastal roads was significantly smaller than island habitats. In particular, females are exposed to the risk of annually repeated roadkills, and the proportion of females decreases rapidly with their growth. If this tendency is general for land crab populations in the coastal areas with roads, significant road mortality of female land crabs during breeding migration can lead to severe population decline in coastal areas. Therefore, it is necessary to take an action to save land crabs crossing coastal roads.

Observing the Impact of Confinement on the Rearing of Land Crabs

The study observed the impact of confinement on the rearing of land crabs in an attempt to produce crabs that can be consumed without having to worry about their unwholesomeness, traceability and also the possibility of producing crabs all year round.Two species of the land crabs were observed for five months: 35 Rainbow land crabs, obtained from Ada, a suburb of the Greater Accra Region of Ghana and 20 Blue land crabs obtained from Sokode, a suburb of the Volta Region of Ghana. the study investigated the 55 land crabs by observing their coexistence, feeding and reproduction in confinement. Dealers in land crabs and other resource persons who had some experience with land crabs where interviewed. At the beginning of the study, the average weight of a male rainbow land crab was 3.3 pounds and that of a female was 3.0 pounds. However, at the end of the study the average weight recorded for the male Rainbow land crab was 5.7poundsand that of the female was 5.4pounds. The number of rainbow land crabs that died during the cause of the study was 7 and 12 escaped resulting in 16 of them remaining by the end of the study. Six of the crabs lost their appendages, one female moulted, 4 female crabs produced eggs and spawned. The only female Blue land crab that survived produced eggs in confinement but later died after three weeks from the commencement of the study. Results of the study showed that the Rainbow land crabs are hardier as compared to the Blue land crabs and thus, the best specie that can be reared in confinement. The Rainbow land crabs can be reared in confinement for a minimum period of five months if the confined area is darkened and hideout accessories provided. The crabs can be fed on a range of diets, from fish, vegetables to leftovers from the kitchen. However, the crabs seem to prefer sugar cane, palm fronds and fruits. The female Rainbow land crabs are capable of spawning in confinement when provided with the right conditions and environment.