Descriptions of two new shell-dwelling species of Metriaclima (Cichlidae) from Lake Malaŵi, Africa

Metriaclima is the most speciose genus of rock-dwelling fishes (mbuna) found in Lake Malaŵi with 32 described species and with about 40 recognized forms that still await formal description. The genus is comprised of many geographically narrow populations restricted to specific habitat landmarks, such as reefs or islands. A few species have taken to the open sandy habitat where empty gastropod shells provide shelter. Two species of such shell-dwellers are here described as new. A combination of a black submarginal band in the dorsal and anal fins and five or fewer bars on the flank distinguishes Metriaclima ngarae sp. n. and M. gallireyae sp. n. from all other species of Metriaclima. Metriaclima ngarae sp. n. differs from M. gallireyae by a greater interorbital width and by a greater ratio of the snout length in the distance between snout tip and pelvic fin origin. Adult males of M. gallireyae have a blue-brown overall coloration obscuring the bar pattern on the flank while males of M. ngarae and those of the closely related M. lanisticola retain the bar pattern and have a coloration very similar to that of females.

Rare tiger beetles (Coleoptera: Carabidae, Cicindelinae) of Croatia: new findings and current distribution

Here we present new records of two rare tiger beetles in Croatia, their distribution and habitat selection. Cylindera trisignata trisignata (Dejean, 1822) was recorded in Croatia,for the first time in 115 years, on Mljet Island in Blace Bay. Specimens were collected on a sandy beach, 5 - 6 m from the water’s edge sea coast. Cylindera arenaria viennensis (Schrank, 1781) was found in Croatia, for the first time in 67 years, in Podravina, in Kloštar Podravski. It was collected in an area previously exploited for sand mining, which was later abandoned and left to the natural succession. Both species were recorded in rare natural or semi-natural sandy habitat types that are endangered in Croatia. The survival of these and other psammophilous species depends on the suitable management and protection of sandy habitats.

High-throughput simulations indicate feasibility of navigation by familiarity with a local sensor such as scorpion pectines

Scorpions have arguably the most elaborate “tongues” on the planet: two paired ventral combs, called pectines, that are covered in thousands of chemo-tactile peg sensilla and that sweep the ground as the animal walks. Males use their pectines to detect female pheromones during the mating season, but females have pectines too: What additional purpose must the pectines serve? Why are there so many pegs? We take a computational approach to test the hypothesis that scorpions use their pectines to navigate by chemo-textural familiarity in a manner analogous to the visual navigation-by-scene-familiarity hypothesis for hymenopteran insects. We have developed a general model of navigation by familiarity with a local sensor and have chosen a range of plausible parameters for it based on the existing behavioral, physiological, morphological, and neurological understanding of the pectines. Similarly, we constructed virtual environments based on the scorpion’s native sand habitat. Using a novel methodology of highly parallel high-throughput simulations, we comprehensively tested 2160 combinations of sensory and environmental properties in each of 24 different situations, giving a total of 51,840 trials. Our results show that navigation by familiarity with a local pectine-like sensor is feasible. Further, they suggest a subtle interplay between “complexity” and “continuity” in navigation by familiarity and give the surprising result that more complexity — more detail and more information — is not always better for navigational performance.Author summaryScorpions’ pectines are intricate taste-and-touch sensory appendages that brush the ground as the animal walks. Pectines are involved in detecting pheromones, but their exquisite complexity — a pair of pectines can have around 100,000 sensory neurons — suggests that they do more. One hypothesis is “Navigation by Scene Familiarity,” which explains how bees and ants use their compound eyes to navigate home: the insect visually scans side to side as it moves, compares what it sees to scenes learned along a training path, and moves in the direction that looks most familiar. We propose that the scorpions’ pectines can be used to navigate similarly: instead of looking around, they sweep side to side sensing local chemical and textural information. We crafted simulated scorpions based on current understanding of the pectines and tested their navigational performance in virtual versions of the animals’ sandy habitat. Using a supercomputer, we varied nine environmental, sensory, and situational properties and ran a total of 51,840 trials of simulated navigation. We showed that navigation by familiarity with a local sensor like the pectines is feasible. Surprisingly, we also found that having a more detailed landscape and/or a more sensitive sensor is not always optimal.

A new short brown unpatterned moray eel Gymnothorax andamanensis (Muraenidae: Muraeninae) from Andaman waters, India

Gymnothorax andamanensis sp. nov., a new short brown moray eel, is described here on the basis of two specimens collected from Port Mout, Port Blair, South Andaman (11.659327°N; 92.696148°E), caught using baited hand-lines in a sandy habitat at a depth of less than 2 m. The species is characterized in having the dorsal-fin origin before the gill opening, pre-anal length 2.1–2.2, jaw pores with black rim, two branchial pores, predorsal vertebrae 3, preanal vertebrae 57 and total vertebrae 135–136, teeth smooth, three large fang-like median intermaxillary teeth, biserial maxillary and uniserial vomerine teeth, and dentary teeth biserial with two teeth in each side in the second row of the dentary. The new species is compared with all 10 short brown unpatterned moray eels known from the world and two from Indian waters.

Cycas micronesica Trees Alter Local Soil Traits

Cycad plants possess uncommon morphological, chemical, and ontogenetic characteristics and they may introduce localized changes in soil traits that increase habitat heterogeneity. We used mature Cycas micronesica K.D. Hill trees growing in a range of soil types in Guam, Rota, and Yap to quantify differences between the soils beneath target trees and paired non-target soils away from cycad trees. The chronic presence of a C. micronesica tree introduced numerous localized changes in soil traits, increasing the heterogeneity of elemental stoichiometry in the community. Nitrogen, carbon:phosphorus, and nitrogen:phosphorus were increased in target soils among every soil type. Carbon increased and phosphorus decreased in most target soils. The habitats revealing the greatest number of elements with differences between target and non-target soils were the habitats with acid soils. The greatest number of metals exhibiting differences between the target and non-target soils occurred in the impoverished sandy habitat. This is the first report that indicates a cycad tree increases community spatial heterogeneity by localized changes in soil chemistry. Contemporary declines in cycad populations due to anthropogenic threats inadvertently decrease this spatial heterogeneity and its influences on primary producers in the landscape then cascading effects on the food web.

Seasonal variability of phytoplankton in the shallow waters of the southern Baltic Sea

The Baltic Sea is characterized by seasonal variation of phytoplankton structure. These organisms are particularly sensitive to changes in various environmental factors. Because of annually repeated changes, turnover of species composition, abundance and biomass of phytoplankton is observed. Spatial and temporal variability of individual phytoplankton groups is diversified in a district parts of the Baltic Sea. Therefore, of three different coastal areas were chosen: Ustka – estuary habitat, Poddąbie – sandy habitat and Rowy – rocky bottom habitat. The aim of this paper is to determine temporal and spatial structure of phytoplankton occurrence chosen coastal areas between November 2014 and September 2016. All three studies regions the same dominants, abundance and biomass were observed. Only in Ustka region increase of the diatoms was observed. Which could see the cause of river waters wave. Seasonal phytoplankton studies in three selected habitats revealed, that in those areas that abundance and biomass is similar (75%-80%). Based on this evaluation it is can be stated that conducting phytoplankton more frequently is more important than number of research stations.

Burrowing Time of the Three Indonesian Hippoid Crabs After Artificial Dislodgment

Three species of hippoid crabs are the target species of intertidal fishery along coastal line in District Cilacap, south Java; namely Emerita emeritus, Hippa adactyla and Albunea symmista. In Adipala sandy beach, Cilacap an experiment was conducted to reveal the burrowing time and velocity of the crabs. The experiment was performed by removing the crabs from their burrows, measuring their carapace length, and releasing them immediately on the substrate. Burrowing time was measured from the start of burrowing to the disappearance of the entire carapace under the sediment surface. Among the three species, E. emeritus had the fastest burrowing time. As a consequence in terms of velocity, the burrowing velocity of Albunea symmista was higher than that of Hippa adactyla and Emerita emeritus; meaning that with the same size A. symmista needs longer time to burrow. By evaluating with other previous studies, the burrowing time and burrowing velocity of the three sand crabs were comparable. The ability of fast burrowing in the three species seems likely to be the advantage for their survival in large wave disturbed coarse sandy habitat and for their ability to widely exist along the sandy coast of south Java. Keywords: behavior; Indian ocean; intertidal; sand crab; south Java; swash zone

Influence of the shoot density of Halodule wrightii Ascherson from rocky and sandy habitats on associated macroalgal communities

This study evaluated the influence of the shoot density of the shoal grass Halodule wrightii on the composition of the associated algal community, in rocky and sandy habitats on the coast of Ceará in northeastern Brazil. The phycological community included 18 species in 10 families, members of Rodophyta (72.2%), Chlorophyta (22.2%) and Phaeophyceae (5.5%). The largest proportion were epilithic (50%), followed by epiphytes on H. wrightii (38.4%), epipsammics (8%), and epiphytes on other algae (4%). Epiphytes on H. wrightii occurred mainly associated with rhizomes, but also tendrils of H. musciformis occurred attached to the leaves. The phycological community varied according to the density of H. wrightii, independently of particular characters of the meadows, although both habitat and other environmental variables seemed to influence the macroalgae composition and diversity. The rocky habitat was more diverse than the sandy habitat, but in the sandy habitat the shoal grass was important for algal settlement in areas where hard substrates were scarce or absent.