Coastal Paleoenvironment

In semi-terrestrial crabs, the production of sounds has been recognized to be related to courtship communication dynamics. The present study aimed to assess if the crab Neohelice granulata (Varunidae) was able to emit acoustic signals and if they played a role in the crab's behaviour. We also assessed the locomotor behaviours to examine these parameters in different mating contexts of crabs. The study was divided into two different experimental conditions: 'solitary experiment' (consisting of three combination layouts with male, unreceptive and receptive females alone) and 'group experiment' (consisting of mixed combinations layouts of males, unreceptive, and receptive females). Synchronized acoustic and video monitoring systems were used to record the acoustic signals and locomotor behaviours of alone and grouped specimens. The greatest values of locomotor behavioural parameters were observed in layouts with receptive females alone and with 2 males plus 1 receptive female, probably related to courtship behaviour. N. granulata produced two distinct signals, a multi-pulse rasp signal (highest numbers were recorded in layouts with male alone and with 2 males plus 1 receptive female) and a single rasp signal. These results may suggest that males use the multi-rasp signal to advertise their presence to other males or to attract receptive females. Communication . Semi-terrestrial crab . Neohelice granulata . Acoustic signals . Mating behaviour 2015), aggressive territorial behaviour (Busnel 1963; Buscaino et al. 2011a) and defence (Meyer-Rochow et al. 1982). Several authors suggest that the use of acoustic signals is crucial for reproductive behaviour (Parker et al. 1998; Buscaino et al. 2015) and mate choice. In this context, the combined effects of chemical (Bushmann and Atema 2000; Sal Moyano et al., 2014), visual (Christy and Rittschof 2010; Baldwin and Johnsen 2012) and acoustic signals (Salmon and Horch 1972; Popper et al. 2001) can modulate the attraction, recognition and assessment of a potential mate. Semi-terrestrial crabs produce acoustic signals by several methods (von Hagen 1975), although rapping (striking of a Communicated by: Matthias Waltert

More than 500 nearly complete specimens of the Atlantic ghost crab Ocypode quadrata (Fabricius) were collected from the upper Pleistocene to Holocene Anastasia Formation along beaches in Brevard County, Florida. Such whole-body decapod crustaceans are rare in Quaternary deposits of the southeastern United States. The low degree of disarticulation and the posture of the crabs indicate that they died while in their burrows, probably by winterkill. Fossil O. quadrata were found in two conditions: those with a clearly crab-like form, bearing a loose, friable matrix of shell hash with little cementation, no visible abrasion, no calcite infilling, and no attached fossil or Recent epibionts; and those that were barely recognizable as crabs, with a thick layer of heavily cemented matrix, a highly sand-abraded (polished) surface, some voids filled with calcite-cemented grains or calcite crystals, and some with Recent epibionts in exposed cavities. The nonabraded crabs with friable matrix have been recently exhumed from a poorly consolidated part of the Anastasia Formation or from the sand dunes or upper beach escarpment by storm waves, whereas the abraded crabs have been cast upon the beach from the nearshore subtidal zone by storm waves. Deposition of the Anastasia Formation is thought to have occurred approximately 110,000 YBP. The barrier-island-sand-dune system along the central East Coast of Florida is believed to have formed within the last 7000 yr. The abraded fossil crabs could have accumulated over the past 110,000 yr, but the nonabraded specimens, if derived from the existing beach, are considerably younger.

The present study compared the morphometric characters of Callinectes pallidus (Rochebrune, 1883) (Crustacea: Decapoda) collected from two coastal areas in Lagos, Nigeria, as a measure of investigating the degree of susceptibility of the species to environmental stress. Thirteen different morphometric characters (distances) which included eye cavity length (ECL), inter-orbital distance (IOD), medial peduncle width (MPW), carapace total length (CTL), carapace total width (CTW), carapace final width (CFW), width of the joining between the propodus and the movable chela thigh (PCT), chela dactylus length (CDL), first movable chela width (FMW), 2nd, 3rd and 4th pereiopod merus width (PMW), merus length (ML), abdomen total length (ATL) and abdomen first suture width (AFW) were measured with precision calliper with an accuracy of 0.01 mm. Differences in mean morphometric distance were tested with T-test and Z-test while the standardized values were examined with…

The present study compared the morphometric characters of Callinectes pallidus (Rochebrune, 1883) (Crustacea: Decapoda) collected from two coastal areas in Lagos, Nigeria, as a measure of investigating the degree of susceptibility of the species to environmental stress. Thirteen different morphometric characters (distances) which included eye cavity length (ECL), inter-orbital distance (IOD), medial peduncle width (MPW), carapace total length (CTL), carapace total width (CTW), carapace final width (CFW), width of the joining between the propodus and the movable chela thigh (PCT), chela dactylus length (CDL), first movable chela width (FMW), 2nd, 3rd and 4th pereiopod merus width (PMW), merus length (ML), abdomen total length (ATL) and abdomen first suture width (AFW) were measured with precision calliper with an accuracy of 0.01 mm. Differences in mean morphometric distance were tested with T-test and Z-test while the standardized values were examined with…

Information about the roles of both sexes in pair formation is required to better understand the mechanisms involved in sexual selection. Mate choice could depend on the courtship behavior, involving chemical, tactile and visual signals. We determined if Neohelice granulata mate choice is based on female or male choice, considering visual and chemical with contact and without contact signals between partners and different categories of individuals: receptive and unreceptive females; and large, small, mated or unmated males. Experiments showed that mate selection was based on receptive female's choice using chemical signals, but not visual ones. Since copulation occurs during high and low tides, water-borne chemical signals would be preferentially used during high tide, while contact ones during low tide. Females preferred large and unmated males, while males did not seem to recognize receptive females using chemical neither visual signals. Females were capable of detecting the presence of the chemical signals released by large and unmated males, but not its amount. It is proposed that small and mated males are probably releasing different types of chemical signals, not attractive to females, or that they are not emitting any signal.

Neohelice granulata is an endemic, burrowing intertidal species of crab distributed in mudflats and saltmarshes of bays and lagoons
along the coast, from southern Brazil to northern Patagonia (Argentina). It is widely known in modern population studies dealing with ecology,
genetics, physiology, and burrowing. However, it is known in the fossil record only from the mid-Holocene of Buenos Aires, from deposits
corresponding to the last marine transgression. The material comprises eleven almost complete specimens, six isolated carapaces and six isolated chelipeds, all preserved in micritic and sandy concretions of different shapes and sizes formed within their burrows. Diagenetic processes produced dorsoventral crushing of all of the specimens to different degrees but they are generally well preserved. No burrows were unambiguously identified, but the articulated nature of the exoskeleton suggests preservation within burrows. A winter kill might have been the
cause of this assemblage, which also includes molluscs, cirripeds, and vertebrates. Herein, we describe in detail and for the first time this material from Parque Pereyra Iraola, Buenos Aires, Canal de las Escobas Formation, Destacamento Río Salado Member, which includes a discussion on the taphonomy and paleoenvironmental implications of the assemblage.