Two species of paguroid hermit crabs, Ciliopagurus liui Forest, 1995 (Diogenidae) and Pagurus spinossior n. sp. (Paguridae), are reported from the Kerala State, southwestern India. Ciliopagurus liui, is first recorded from the Indian Ocean. This species was originally described on the basis of a single male specimen from the Tonkin Gulf in the South China Sea, though its geographical range also included Japan, based on literature. Supplemental description and illustrations are provided for better understanding of the diagnostic features of this little known species. Pagurus spinossior n. sp., described on the basis of a single male specimen, appears closest to P. spinulentus (Henderson, 1888), known only by the holotype from the Philippines, but the lack of spinules on the dorsal margins of the dactyli of the second pereopods, the different shape of the anterior lobe of the thoracic sternite 6, and the more numerous spines on the terminal to posterior margins of the telson distinguish the new species from P. spinulentus.
A new species of the hermit crab genus Diogenes Dana, 1851 (Diogenidae), D. canaliculatus, is described and illustrated on the basis of material from off the Kerala State, southern India. It is referred to the D. edwardsii (De Haan, 1849) species group, and compared with D. bicristimanus Alcock, 1905, D. fasciatus Rahayu & Forest, 1995, D. laevicarpus Rahayu, 1996 and D. moosai Rahayu & Forest, 1995. The characteristically sculptured left chela and the unarmed dorsal margins of the propodi of the second and third pereopods distinguish the new species from these congeners.
A new species of the hermit crab genus Paguristes Dana, 1851 (Diogenidae), P. luculentus, is described and illustrated on the basis of three male specimens collected from off the Kerala State, southwestern India. It belongs to the species group characterized by the posterior lobes of the telson unarmed on the terminal margins, but the characteristic armature of the chelae and carpi of the chelipeds, consisting of a covering of numerous small corneous-tipped spines, and the presence of numerous small corneous-tipped or corneous spines on the mesial faces of the dactyli of the second pereopods immediately distinguish the new species from other congeneric species. The new species represents the ninth of the genus known from Indian waters.
Estuarine sediments are important sites for denitrification, which is microbially mediated reduction of nitrate to dinitrogen that also influences global climate change by co-production of nitrous oxide, a potent greenhouse gas. Physicochemical properties and nutrients of sediment samples that influence denitrification rate were studied in Ashtamudi estuarine sediments. They were pH, electrical conductivity (EC), salinity, nitrate-nitrogen (NO-N), exchangeable ammonia (NH-N), total kjeldahl nitrogen (TKN) and organic carbon (Corg). Sediment samples were collected from six stations during summer, monsoon of 2013 and 13 stations from monsoon 2014 and summer 2015. The sedimentary denitrification potential ranged from 0.49 ± 0.05 to 4.85 ± 0.782 mmol NO m h. Maximum denitrification was observed in S4, which is attributed to a local anthropogenic source coupled with intense rainfall episode preceding the sampling season of monsoon 2013. However, this trend was not repeated in the subsequent monsoon samples. This shows that in Ashtamudi, monsoonal effects do not influence sedimentary denitrification. Among the various environmental variables, NO-N, Corg and NH-N were the key factors that influence denitrification in the Ashtamudi estuarine sediments. Among these key factors, NO-N was the limiting factor for denitrification, and hence, it is of prime importance to understand the source of NO-N that fuel denitrification in the sediments. In Ashtamudi, the concentration of NO-N in overlying water was very less, which suggests reduced nitrogen yield in the estuary from the fluvial input of Kallada River and agricultural runoff. Sedimentary NO-N correlated with denitrification which reveals that denitrification is coupled with nitrification in the sediments. This is further explained by the fact that NH-N positively correlated with denitrification. The anoxic sediments were the source of ammonia for nitrous oxide production by nitrogen mineralisation. Also, the Corg in sediment samples were sufficient to support denitrification and Corg was an important factor favouring but not limiting denitrification. The results of sediment denitrification in Ashtamudi can be a model for tropical estuaries experiencing unpredictable rainfall as well as high temperature than temperate systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.