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The understanding of the dynamical behavior of seismic phenomena is currently an open problem, mainly because seismic series can be considered to be produced by phenomena exhibiting dynamic phase transitions; that is, with some complexity. For this purpose, the Middle America Trench in central Mexico is considered a natural laboratory for examining subduction because of its heterogenous natural structure. In this study, the Visibility Graph method was applied to study the seismic activity of three regions within the Cocos plate: the Tehuantepec Isthmus, the Flat slab and Michoacan, each one with a different level of seismicity. The method maps time series into graphs, and it is possible to connect the topological properties of the graph with the dynamical features underlying the time series. The seismicity analyzed was monitored in the three areas studied between 2010 and 2022. At the Flat Slab and Tehuantepec Isthmus, two intense earthquakes occurred on 7 and 19 September 2017, respectively, and, on 19 September 2022, another one occurred at Michoacan. The aim of this study was to determine the dynamical features and the possible differences between the three areas by applying the following method. First, the time evolution of the a- and b-values in the Gutenberg–Richter law was analyzed, followed by the relationship between the seismic properties and topological features using the VG method, the k–M slope and the characterization of the temporal correlations from the γ-exponent of the power law distribution, P(k) ∼ k−γ, and its relationship with the Hurst parameter, which allowed us to identify the correlation and persistence of each zone. [ABSTRACT FROM AUTHOR]

Introduction: Clypeaster europacificus is a species of sand dollar found from 0 to 200 m in the Gulf of California. Objective: Describe the morphology and relative growth in the test of C. europacificus. Methods: We measured 1 846 museum specimens of C. europacificus (N = 1 846) and analyzed growth pattern in 32 specimens from Baja California Sur, Mexico (64 m depth). We studied five variables: major radius (R) (independent variable), minor radius (r), length of anterior petal (LP), total test area (A) and dry weight (P). Results: The petaloid cover area and the outline of the test are the important taxonomic characters for C. europacificus: they range from almost round in small specimens (≤ 3 cm in radius) to wavy, emphasizing a pentagonal outline, in larger organisms (≥ 3.1 cm in radius). Conclusions: There is negative allometric growth in the relationships R vs. r, R vs. A, and R vs. P; while the relationship R vs. LP has positive allometric growth. [ABSTRACT FROM AUTHOR]

We have estimated empirical relationships that associate the age of the Pacific oceanic lithosphere with the seismic energy released on both flanks of the East Pacific Rise. The equations found were tested by comparing other empirical equations based on lithospheric age, heat flow, and bathymetric depth published by other authors. The results of this study are consistent for seafloor ages ranging between 1 and 4 Ma throughout three perpendicular cross-sections. These cross-sections are located between the diverging plate boundary of the northern Pacific Ocean up to the subduction zone of western Mexico. Our results allow us to infer the depth of the 1200 °C isotherm underneath the analyzed plates, from the mid-oceanic ridges up to the subduction zones. The distribution of seismic energy released within the limits of the Rivera and Pacific plates shows a gradual decrease from the ridge axis to the oceanic trench. However, an increase of seismic activity is recorded near the Mesoamerican Trench, where the Rivera Plate subducts under the North American Plate at an angle of ~ 46°. This anomaly is a consequence of the convergence, thrust and deepening of the oceanic plate. Due to the homogeneity of this plate, it is possible to infer the projection of isochrones in the subduction zone. Although the thickening of the thermal boundary layer may be estimated from the square root function of the seismic energy, this brittle–ductile transition in the subduction zone deepens exponentially with relation to the computed energy. [ABSTRACT FROM AUTHOR]

Epitomapta simentalae sp. n. occurs in depths of 4-10 m off the Mexican Central Pacific coast. It is distinctive in having twelve tentacles, each tentacle with two or three pairs of digits and four to six sensory cups, lacking papillae or oval bumps and in reaching a maximum length of 50 mm in life. [ABSTRACT FROM AUTHOR]

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A 3-year-old male Bloodhound dog was presented to a private veterinary hospital at Ciudad Victoria, Tamaulipas, Mexico, with a 2-week history of weight loss, generalized weakness, anorexia and ptyalism. Results of a hemogram revealed moderate anemia with a chronic inflammatory leukogram. Also, various neutrophlis (approximately 10%) containing elongated pale blue staining intracytoplasmic inclusions, compatible with gametocytes of Hepatozoon spp were observed. Up until now, this is the first case report of canine hepatozoonosis detected in Tamaulipas. [ABSTRACT FROM AUTHOR]

Describes an allozyme analysis of host selection by bark beetles in Mexico. Genetic differences among different species of bark beetles; Damages brought by the species to the pine forests; Relationship between the genetic composition of some pine tree species and their susceptibility to bark beetle attack.

Introduction: In Mexico, there are two recorded living species of Cassiduloida: Cassidulus caribaearum and Rhyncholampas pacifica. Most of the taxonomic studies on cassiduloids have used external morphology, pedicellariae and morphometric characters; however, the intraspecific variation of quantitative and qualitative characters has been poorly evaluated. Objective: To compare the basic morphology of R. pacifica and C. caribaearum. Methods: We examined a total of 2 158 specimens of R. pacifica and C. caribaearum, selecting 50 to evaluate shape and size with linear regression and Principal Component analysis. We selected an additional 62 specimens per species to identify significant character correlations and morphological groups within species. Results: There is a direct relationship between Test length and Test width. Test height/Test width, and Total length (oral view)/Distance from the ambitus to the peristome apex, are the two main ratios to distinguish both species. C. caribaearum is more dorsoventrally compressed and has a round peristome base; versus R. pacifica has a tall and triangular one. There are four morphological groups of C. caribaearum and two groups for R. pacifica. Conclusions: These two species can be distinguished with reliable morphological characters, in which peristome shape suggests that R. pacifica is more adapted to burrowing deeper into certain types of substratum. [ABSTRACT FROM AUTHOR]

Introduction: Cucumarids are a cosmopolitan group of sea cucumbers that inhabit rocky-sandy sediments, from the intertidal zone to the hadal zone. Objective: To present new records for the Mexican Pacific. Methods: We applied stereoscope and scanning electron microscopy to external and internal morphology of specimens in the collection of the National Autonomous University, Mexico. Results: We present a taxonomic synopsis of cucumarids in the Mexican Pacific and review their taxonomy on the ossicles. The taxonomic identity of Pseudocnus curatus, Pseudocnus dubiosus and Pseudocnus lubricus is confirmed, and the presence of Trachythyone peruana is ruled out. Conclusions: Four new records are presented for the Mexican Pacific: Leptopentacta nina, Pseudocnus curatus, Pseudocnus dubiosus and Pseudocnus lubricus. [ABSTRACT FROM AUTHOR]

Introduction: Chamela bay is located in the central portion of the coast from the Jalisco state, Mexico and is an important protected natural area. Despite this, the study of echinoderms in the area is incipient. Objective: To provide an updated checklist, descriptions of the species and a taxonomic key of the ophiuroids from Chamela bay. Methods: We collected specimens from 1998 to 2018, and also analyzed information from the literature and specimens deposited at international scientific collections from Chamela bay. Results: 19 species of ophiuroids are reported for the study area, distributed in two orders, seven families, and 11 genera. Seven of these correspond to new records for the area, one to a new record for Jalisco state, and two possibly represent new species. The biodiversity of ophiuroids in Chamela bay represents 15.2 % of ophiuroid species from the Mexican Pacific and 73 % from Jalisco. The number of known echinoderms in Chamela bay is increased to 48 species. Conclusions: The most complete checklist of the class Ophiuroidea in Chamela bay, Jalisco, is presented. The information provided can be used for other areas of the eastern Pacific. Chamela bay is important in terms of species richness due to its environmental heterogeneity and numerous islands. [ABSTRACT FROM AUTHOR]

Asian citrus psyllid, Diaphorina citri Kuwayama, is the vector of "Huanglongbing" disease. Different insecticides are used to control the vector by a government containment program to prevent dissemination of disease in citrus growing areas in Mexico. Increased selection pressure on field populations can result in resistance to insecticides. The goal of this study was to determine susceptibility baselines in a laboratory strain of Asian citrus psyllid susceptible to 11 insecticides from five toxicological groups and determine diagnostic doses to test in eight populations from Tahiti lime, Citrus latifolia Tan., and Mexican lime, Citrus aurantifolia Swingle, orchards with different patterns of insecticide use. Resistance ratios were calculated in comparison with data from a susceptible strain in a laboratory in Florida. Most calculated LD50 and LD95 values corresponded well with mortalities caused by diagnostic doses. Asian citrus psyllids from Apatzingan, Michoacan were very resistant to imidacloprid, 4265.6-fold; dimethoate, 106.5-fold; chlorpyriphos, 26.5-fold; and slightly to thiamethoxam, 13.8-fold. At Cofradia de Morelos, Colima, resistance to imidacloprid was 25.6-fold. Resistance to imidacloprid (17.5-fold) and thiamethoxam (12.0-fold) was detected at Cerro de Ortega, Colima. Similar resistance was observed at Tepic, Nayarit, to imidacloprid (13.8-fold) and thiamethoxam (19.3-fold). Psyllids at Casimiro Castillo, Jalisco were resistant to chlorpyriphos (20.6-fold). At El Limon, Jalisco, resistance was found only to thiamethoxam (14.2-fold). Results are similar to those found by Tiwari et al. (2011, 2013) in Florida; however, resistance to neonicotinoids and organophosphates was greater in Asian citrus psyllids in Mexico than those in Florida. [ABSTRACT FROM AUTHOR]

Theileria cervi is a tick-borne protozoan that infects different deer species around the world. Clinical diseases due to Theileria cervi have been reported in white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) in the USA, however, information about this parasite has not been documented in Mexico. Here, blood samples from three white-tailed deer (Odocoileus virginianus) from a region in northeastern Mexico were analyzed by blood smear, PCR, and DNA sequencing. The results confirmed the presence of T. cervi for the first time in white-tailed deer in Mexico., (Copyright © 2020 Elsevier B.V. All rights reserved.)