La Revista The Biologist (Lima) [Biologist (Lima)] publicada por la Escuela Profesional de Biología, Facultad de Ciencias Naturales y Matemática de la Universidad Nacional Federico Villarreal (EPB- FCCNM-UNFV) y por ASEFIM Instituto de Capacitación y Consultoría, Lima, Perú, es una publicación de periodicidad semestral y sus artículos son arbitrados, tiene como objetivo publicar la producción científica en todos los aspectos de la investigación biológica, salud y de ciencias ambientales en trabajos de investigación originales y revisión de tópicos de importancia biológica, salud y de ciencias ambientales. La información que contiene la Revista es de responsabilidad exclusiva de los autores que la proporcionan y no compromete la posición de EPB-FCCNM-UNFV y de ASEFIM o de los editores.
Universidad Nacional Federico Villarreal. Facultad de Ciencias Naturales y Matemática. Escuela Profesional de Biología
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Formal record of Jabiru mycteria (Lichtenstein, 1819) in the el paraíso wetland (Lima, Peru) and contribution to the knowledge of its distribution on the Peruvian coast
The first formal record of Jabiru mycteria (Lichtenstein, 1819) in the El Paraíso Wetland, Lima, Peru, is reported, based on an observation made on September 8, 2024, documented by photographic record with precise coordinates. Although there are previous observations on citizen science platforms such as iNaturalist, these do not constitute verified records in the specialized literature. Additionally, an exploratory model was developed in MaxEnt to assess the importance of bioclimatic variables in their distribution in the coast, determining that the annual thermal amplitude was the only decisive predictor while the rest of the variables showed a minimal or zero contribution to the observed pattern. The presence of the species in this wetland suggests the use of the site as a feeding area within its range on the central Peruvian coast. This record highlights the ecological importance of El Paraíso Wetland as a habitat for bird species of high conservation value and underscores the need to strengthen ecosystem management and protection actions in the face of anthropogenic threats and environmental changes.
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Description of the First Zoea of Armases occidentale (Smith, 1870) (Decapoda: Sesarmidae)
Within the Sesarmidae family, species of the genus Armases were separated from the genus Sesarma based on morphological characteristics observed in adult specimens; it is known that differences between species can also be found at the larval stage, making larval descriptions particularly useful. Only representatives from the Atlantic Ocean have been described, and none from the Pacific, leaving open the question of whether larval morphological differences exist between species from both oceans. A gravid specimen of Armases occidentale (Smith, 1870) was obtained from bait used in artisanal fishing near Posorja; it was maintained under controlled conditions with a salinity of 32 UPS and a temperature of 24 °C until spawning, at which point 20 larvae were collected for measurement and description. Comparing the morphology with descriptions of other larvae reported in the literature, the results demonstrate that the setaxia of the basal endite and the endopod of the maxillula and maxilla are distinctive of the genus, and that A. occiendale exhibits the same characteristics as its congener A. cinereum (Bosc, 1801). It is suggested that the nomenclature used for larval descriptions be standardized to develop taxonomic keys that allow for the identification of larvae in zooplankton.
Population density of Ocypode gaudichaudii h. Milne Edwards & Lucas, 1843 (Decapoda: Ocypodidae) on sandy beaches of Guayas, Ecuador
Sandy beaches provide recreational and tourism services and offer coastal protection, in addition to serving as the habitat of the ghost crab Ocypode gaudichaudii H. Milne Edwards & Lucas, 1843, where its populations may be affected by human activities. In this regard, the population density and structure of O. gaudichaudii were assessed on four beaches in the province of Guayas, Ecuador, during May–June 2025, using the quadrat method to count burrows and measure burrow entrance diameter (BED) as an indirect estimator of the crab’s body size; a total of 832 burrows were evaluated. The results showed that Engabao was the beach with the highest number of organisms and the greatest variability in burrow opening diameter, suggesting a more representative and abundant population structure compared to the others. This study is a first step toward future assessments of the ecological status of the sandy beaches of the Ecuadorian mainland.
Assembly of aquatic macroinvertebrates in lotic ecosystems of Reserva natural el Caduceo, San Martin-Meta, Colombia
Aquatic macroinvertebrates are characterized by their high variability and adaptability to environmental changes, allowing them to play a fundamental role in the functioning of aquatic ecosystems and making them key bioindicators of water quality. This study aimed to analyze the relationship between physicochemical variables of water bodies and the structure of macroinvertebrate communities in the El Caduceo Natural Reserve, located in the Colombian Orinoquía piedmont. Quantitative and qualitative sampling was conducted at two sites: a stream and the sub-basin of the Camoa River. Physicochemical variables, including pH, temperature, total dissolved solids, and electrical conductivity, were measured, and D-net, kick net, and Surber sampler were used for organism collection. Taxonomic identification was performed to family and genus levels. Water quality was assessed using the BMWP/Col index, and diversity and evenness metrics were estimated. Results showed that the stream exhibited higher richness, diversity, and evenness, whereas the Camoa River presented a simplified community dominated by tolerant taxa such as Trichoptera. BMWP/Col values indicated moderately polluted conditions in the stream and highly polluted conditions in the river. These findings suggest that dissolved oxygen directly influences community structure and diversity, highlighting the importance of macroinvertebrates as effective tools for environmental monitoring.
Anatomical description of the skull of the fish Hydrolycus armatus (Jardine & Dchomburgk, 1841) (Characiformes: Cynodontidae)
Hydrolycus armatus (Jardine & Dchomburgk, 1841), popularly known as peixe-cachorra (dogfish) in the Tocantina region of Maranhão, is a species found in flowing waters and lakes in the state of Maranhão, and plays a significant role in feeding the riverside population and local economy. The objective of this study was to describe the main bones that make up the skull of H. armatus. For this study, the material was dissected and detailed osteological descriptions of the skull were analyzedfrom lateral-dorsal and antero frontal views. Characteristics similar to those described for the species were observed, such as a set of structures located in the upper part, such as the dilator operculi above the parasphenoid, which comprises the outer edge of the inner orbital ring, in addition to robust anterior mandibular dentition that expresses the adaptive specialization of the species in its aquatic environment. This analysis contributes to future studies related to the physiological mechanisms of this fish's life, providing valuable information for investigations into its bone morphology and anatomical studies in the Araguaia-Tocantins basin.