Tropical Zoology

Life history of Mexican species of the genus Tlaloc (Cyprinodontiformes, Profundulidae)

Manuel d. J. Anzueto-Calvo — 2024-10-16

Fish of the genus Tlaloc are distributed from southern Mexico to Central America and are a distinctive example of the endemic fauna of the Mesoamerican highlands, which has been scarcely studied in Mexico. The present study provides basic life-history data for the species Tlaloc hildebrandi, T. candalarius, and T. labialis, which are native to the headwaters of the Grijalva-Usumacinta basin in southeastern Mexico. We collected 918 specimens to determine their Length-Weight Relationship (LWR), Relative Condition Factor (Kr), sex ratio, Gonadosomatic Index (GSI), fecundity, and size at first sexual maturity. Both sexes of all species had positive allometric growth, except for T. candalarius females (isometric). Mean Kr and sex ratio values differed significantly among species. Females’ GSI values differed significantly among species but were highest during the dry season in all three species. Absolute fecundity was positively correlated with standard length and weight. Sexual maturity was reached at different lengths among species. Based on these results, we suggest that all three species present an opportunistic life strategy, which is very common in fish of the order Cyprinodontiformes. These results represent a first contribution on the life-history of this group of fish and provide basic information that is fundamental to ensuring their conservation.

Different habitat condition proportions on farms affect the structure and diversity of dung beetle (Coleoptera, Scarabaeidae, Scarabaeinae) communities

Rodrigo Tec Pardillo — 2024-10-03

The continuous changes and increase of land use into ranching and agriculture have caused shifts in the composition and structure of dung beetle communities due to the modification of vegetation structure. The impact of these changes can be approached using dung beetles as ecological indicators. Agricultural, ranching, and forestry are often integrated into the same farm in different proportions (landscape level), and their degree of integration with habitats changes over time and space. We assessed if different habitat proportions of crop, pasture, and forest land on three farms affect the structure and diversity of dung beetle (Coleoptera: Scarabaeinae) communities. Farms included from three to four habitat conditions each (plantations of timber species, banana-coffee plantation, living fences, pastures, secondary and riparian forest). Pitfall traps with dung and carrion as bait were placed across each habitat condition of each farm during three different sampling periods. Across all samplings, 1,198 dung beetle individuals belonging to 21 species were captured. Species diversity and composition vary according to the type of farm and the main factor that modifies this tendency is the proportion of pasture land composing the farm. Farms with a lower proportion of grazing land (11.96% for forestry farms and 32.19% for agricultural farms) and denser vegetation canopy, which cast more shadows, had greater beetle diversity. Conversely, farms having a greater proportion of grazing land had low diversity and a dominant tendency in the species abundance curve. Umbraphile species dominated the forest farm, indicating a strong affinity for shaded environments such as the one provided there, while species displaying no habitat preference exhibited higher abundance in the ranching farm. Additionally, a notable prevalence of small-sized species was observed in the ranching farm, contrasting with a relatively even distribution of sizes in the remaining landscapes. These tendencies suggest that shade positively influences biodiversity conservation. Riparian vegetation, living fences, and banana-coffee plantations are important connectivity elements in agricultural landscapes for shade-adapted dung beetle species.

New range record for Campbell’s monkeys (Cercopithecus campbelli) in West Africa

Nadia Mirghani — 2024-09-24

The current distribution of Campbell’s monkeys Cercopithecus campbelli extends from southwestern Gambia to the western Ivory Coast. In Senegal, it has only been confirmed in the western part of the country. Here, we report for the first time its presence in southeastern Senegal. We obtained camera trap footage of a Campbell’s monkey individual in the Dindefelo Community Nature Reserve located in Kedougou region, 174 km away from its known distribution range. In the footage, a single Campbell’s monkey appears alongside a group of at least nine green monkeys Chlorocebus sabaeus. We discuss different hypotheses that could explain the presence of the Campbell’s monkey in Dindefelo, and conclude that this individual may be a single migrant.

Abundance, distribution and diet analysis of East African common mole rat (Tachyoryctes splendens) in farming fields of Dawachefa District, Northeast Ethiopia

Gezahegn Degefe — 2024-07-24

The East African common mole rat, scientifically known as Tachyoryctes splendens, is a solitary rodent mole that inhabits subterranean environments. This research focused on assessing the abundance, distribution, population structure, and dietary preferences of the East African common mole rat in three specific locations within the Dawachefa locality, Ethiopia, during both the wet and dry seasons. The research was conducted between June 2022 and February 2023. The abundance and distribution of the common mole rat were estimated through fresh mound counts, while live and locally crafted snap conical traps were utilized for capturing them. Stomach content analysis was performed to identify food fragments. Excavations were conducted to examine the burrow system, revealing three elements: a single multi-functional nest, one or more foraging tunnels, and a bolthole. A total of 45 common mole rats (30 males and 15 females) were captured across the three study sites during both seasons. Adults constituted 62.2% of the captured individuals, sub-adults accounted for 24.44%, and juveniles made up 13.33%. The male-to-female ratio was 2:1, with a significant difference in proportions (t=7.746, p=0.001). Although the abundance of common mole rats did not vary significantly among the selected sites, it showed a significant difference between the wet and dry seasons. The analysis of stomach contents revealed a total of 661 isolated food fragments. Grass comprised the largest portion at 34%, followed by sugarcane (31.2%), banana (24.5%), and papaya (10.3%). Understanding the abundance, distribution, population structure, and food preferences of T. splendens in the study area is crucial for developing strategies to address the agricultural yield loss caused by this species.