A new species of Corallana Dana, 1852 (Crustacea: Isopoda: Corallanidae) from the Andaman Islands, northern Indian Ocean

Corallana mishrai sp. nov. collected from dead mangrove roots at Kodiyaghat, South Andaman, Andaman Islands, India is described and illustrated in detail. Corallana mishrai sp. nov. the first definitive record of the genus from India, is characterized by: frontal lamina with short straight (or very weakly convex) lateral margins and the anterior margin forming a strong acute median point; pleotelson length 0.76 greatest width, posterior margin with 5 robust setae; uropodal exopod 7 times longer than greatest width, extending beyond endopod by one fourth of its length; endopod lateral margin slightly convex with 4 RS and PMS, apex forms a slightly obtuse angle with long simple setae, mesial margin weakly convex with 2 RS and PMS; mandible bidentate; transverse row of 6 tubercles present on pereonite 1 and pleonites 2, 3 and 4 lacking lateral tubercles. The status of the genus and its species are reviewed, and two species are transferred to new combinations: Argathona kulai (Bruce, 1982) comb. nov. and Tachaea bidentata (Jones et al. 1983) comb. nov.

First record of Mothocya arrosor Bruce, 1986 parasitizing Euleptorhamphus viridis (van Hasselt, 1823) from India

The first record of Mothocya arrosor Bruce, 1986 parasitizing ribbon halfbeak fish Euleptorhamphus viridis is here reported from the southeast coast of India. The important characters distinguishing M. arrosor from other species in the genus include the body slightly twisted to one side, dorsum weakly convex, coxae of pereonites 6 and 7 distinctly rounded, pleon more completely overlapped by pereonite 7, pleonite 1 scarcely visible in dorsal view, uropod peduncle longer than rami, lacking strongly convex medial and lateral margins. The damage of gill rakers and erosion of gill lamellae were the acute gross lesions observed as a result of isopod infestation.

A zeroth order method for stochastic weakly convex optimization

In this paper, we consider stochastic weakly convex optimization problems, however without the existence of a stochastic subgradient oracle. We present a derivative free algorithm that uses a two point approximation for computing a gradient estimate of the smoothed function. We prove convergence at a similar rate as state of the art methods, however with a larger constant, and report some numerical results showing the effectiveness of the approach.

Fragilaria irregularis sp. nov. a new araphid species (Fragilariaceae, Bacillariophyta) from the River Adegoy, Krasnodar Territory, Russia

During a survey of the diatom flora of the Adegoy River (Krasnodar Territory, Russia), an unknown Fragilaria species (Bacillariophyta) was found that could not be identified using the currently available literature and here we describe it as a new species. The morphology of Fragilaria irregularis sp. nov. was studied using light and scanning electron microscopy and compared to similar species including Fragilaria deformis, F. rinoi, F. septentrionalis and Fragilariforma bicapitata. It differed from these taxa in several characters. Most observed valves showed an irregular striation pattern, a feature not observed in other species. Other important differences include valve outline (linear with parallel margins) and stria density (7–14 in 10 µm, lower compared to all other species). The new taxon has a linear valve outline with parallel to weakly convex margins, subcapitate apices and a very irregular, coarse striation pattern.

Weakly convex hypersurfaces of pseudo-Euclidean spaces satisfying the condition LkHk+1 = λHk+1

In this paper, we try to give a classification of spacelike hypersurfaces of the Lorentz-Minkowski space-time E1n+1, whose mean curvature vector field of order (k+ 1) is an eigenvector of the kth linearized operator Lk, for a non-negative integer k less than n. The operator Lk is defined as the linear part of the first variation of the (k + 1)th mean curvature of a hypersurface arising from its normal variations. We show that any spacelike hypersurface of E1n+1 satisfying the condition LkHk+1 = λHk+1 (where 0 ≤ k ≤ n − 1) belongs to the class of Lk-biharmonic, Lk-1-type or Lk-null-2-type hypersurface. Furthermore, we study the above condition on a well-known family of spacelike hypersurfaces of Lorentz-Minkowski spaces, named the weakly convex hypersurfaces (i.e. on which all of principle curvatures are nonnegative). We prove that, on any weakly convex spacelike hypersurface satisfying the above condition for an integer k (where, 0 ≤ r ≤ n−1), the (k + 1)th mean curvature will be constant. As an interesting result, any weakly convex spacelike hypersurfaces, having assumed to be Lk-biharmonic, has to be k-maximal.

First record of the freshwater copepod Mesocyclops paranaensis Dussart & Frutos, 1986 (Copepoda: Cyclopoida: Cyclopidae) from Colombia

The Neotropical free-living freshwater cyclopoid copepod Mesocyclops paranaensis Dussart & Frutos, 1986 was found in a small temporal pond in La Guajira, northern Colombia. Hitherto, it has been reported from Argentina, Paraguay, and Brazil. This is the first record of this species in Colombia, its northernmost finding in South America, and the fourth locality in which this species has been recorded from. Mesocyclops paranaensis can be distinguished from its closest congeners by a unique combination of the characters of the female, including: 1) leg 4 intercoxal sclerite with two large, acute projections; 2) P3, P4 intercoxal sclerite caudal surface lightly pilose; 3) seminal receptacle with narrow lateral arms and weakly convex anterior margin; 4) second antennary endopodite with seven setae, and insertion of antennary exopodal seta with adjacent spinules; 5)frontal surface of P1 basipodite ornamented with long spinules; 6) posterior margin of anal somite with continuous row of spinules; and 7) inner margin of caudal ramus hirsute. The Colombian population shows some subtle morphological differences with respect to previous reports.

Two new species of the family Rhynchitidae (Coleoptera: Curculionoidea) from Eocene Baltic amber, with key to species and assumed trophic relationships

Two new fossil species of Baltocar Kuschel, 1992 and Pseudomesauletes Legalov, 2001 (Curculionoidea: Rhynchitidae) are described from Eocene Baltic amber. Baltocar sontagae sp. nov. is similar to B. groehni Riedel, 2012 but differs in the shorter rostrum, tarsomere 1 shorter than tarsomere 5 and 1.4× as long as tarsomere 2, longer elytra, and shorter body. Pseudomesauletes lobanovi sp. nov. is similar to P. culex (Scudder, 1893) and P. ibis (Wickham, 1912): the new species differs from P. culex in the larger eyes, longer pronotum, being 0.44× shorter than elytra, and slightly smaller body size; from P. ibis it differs in the smaller body size, rostrum shorter than elytra, and weakly convex pronotum. This is the first record of Pseudomesauletes from Baltic amber and the sixth species of Baltocar. Keys to species of the genus Baltocar and to the Eocene species of the genus Pseudomesauletes are given. Assumed trophic relationships of these fossil taxa are discussed (urn:lsid:zoobank.org:pub:260EBE6E-DA6C-4D6D-A1D2-2C258224622F).