Zoodiversity

RISK ASSESSMENT OF INTRODUCED FISH SPECIES AS A BIODIVERSITY MITIGATION EFFORT IN LAKE TOBA, NORTH SUMATRA, INDONESIA

Agung Batubara — 2025-08-11

Lake Toba has environmental and ichthyofauna diversity degradation due to human activities and invasive introduced fish species. To carry out studies regarding the identification of species, distribution patterns, densities and risks of introduced fish species as the initial information needed through scientific and measurable approaches. Research was conducted in Lake Toba, North Sumatra, Indonesia from June to August 2024 in ten research location. This research uses an exploratory method with measuring parameters including population density, Shannon-Wienner diversity index (H'), Evenness index (E) and Simpson dominance index (C). Furthermore, this research also measures the risk of invasiveness through the Fish Invasiveness Screening Test (FIST). There are nine introduced fish species that have been established in Lake Toba, including Amphilopus labiatus, Aplocheilus panchax, Cyprinus carpio, Mystacoleucus Padangensis, Oreochromis mossambicus, O. niloticus, Poecilia reticulata, Puntigrus tetrazona, and Xiphophorus helleri. Population density values show that P. reticulata has the highest average value reaching 6.02 ind/m², followed by A. labiatus 2.21 ind/m², M. Padangensis 0.21 ind/m², O. niloticus 0.14 ind/m², P. tetrazona 0.08 ind/m², X. helleri 0.03 ind/m², and 0.01 ind/m² in A. panchax, C. carpio, and O. mossambicus, respectively. Diversity index analysis show low diversity (mean of 0.7), evenness index shows unstable community (mean of 0.46), and Simpson dominance index shows the presence of a dominant species (mean of 0.63). The results of the FIST analysis show that five introduced fish species are in the high risk category, three species have a moderate risk and one species has a low risk. O. niloticus, A. labiatus, C. carpio, O. mossambicus, and P. reticulata have a high risk for ichthyofauna diversity and in fact cause low diversity in Lake Toba.

A New Species of the Genus Paramicroplus (Coleoptera, Scarabaeidae, Melolonthinae, Hopliini) from Madagascar

B. M. Vasko — 2025-06-09

An illustrated description and diagnosis of Paramicroplus keithi sp. n. and an updated key to the species of the genus Paramicroplus Lacroix, 1998 are provided. The new species is similar to P. vitellinus Lacroix, 1998, differing by the slightly larger body size, the shape of clypeus, the peculiar shape of aedeagus, and other characteristics.

Population Structure of the Eastern Prawn, Macrobrachium nipponense (Crustacea, Decapoda, Palaemonidae), in the First Years of its Introduction into the Kiliya Delta of the Danube

K. Ye. Zorina-Sakharova — 2025-05-20

The population structure, growth, and relative condition factor of the eastern prawn, Macrobrachium nipponense (De Haan, 1849), in the first years of its introduction into the Kiliya Delta of the Danube were studied. The quantitative predominance of males over females (♀ : ♂ = 1.0 : 2.5) was established, with egg-bearing females comprising 10.0 % of the total prawn population. PCA results indicate that TL and AL are the primary differences separating females from most males, while egg-bearing and non-egg-bearing females differ in most morphometric parameters, with the key traits being RChL, LChL, and 1AbH. LDA results showed that males, egg-bearing and non-egg-bearing females differed significantly in the population based on the studied characteristics. The growth coefficients indicated a positive allometric growth type for males (b = 3.62) and near-isometric growth for females (b = 3.09). For 65.4 of females and 57.8 % of males, the values of the condition factor Kn > 1, indicating high fatness in individuals of both sexes.

A New Species of Danioid Fish (Danionidae, Chedrinae) from Imphal River, North-Eastern India

L. Arunkumar — 2025-05-20

Barilius imphalensis sp. n. is described from the Imphal River, a main head-water tributary of Chindwin River basin in Manipur, a hill grit state of North-Eastern India. It is distinguished from all its congeners in having the following combination of characters: absence of barbels, presence of tubercles on the tip of snout, presence of dentary tubercles, presence of complete lateral lines with 41 scales, pre-dorsal scales 18, head depth at supra-occipital 20.2–23.4 % SL, body depth at dorsal fin origin 25.0–28.1 % SL, pre-anal length 65.1–68.5 % SL, height of dorsal fin 22.9–24.8 % SL, height of anal fin 26.1–28.9 % SL, eye diameter 6.3–6.9 % SL and 26.2–26.8 % HL, inter-orbital width 32.3–38.5 % HL and short blue vertical bars along the body 15–17. Key to species of the genus Barilius of the north-eastern India and their distribution pattern in the six different river drainage systems are provided.

Population Decline of Ground Squirrels, Spermophilus (Rodentia, Sciuridae), in Ukraine and Forecasting Trends

S. V. Mezhzherin — 2025-05-20

Population trends of ground squirrels (Spermophilus citellus, S. suslicus and S. pygmaeus) in Ukraine were assessed using census data from the Plant Protection Inspection Service (1937–2007). Comparing these data with observations from the first decades of the 21st century suggests that ground squirrel populations have declined significantly, with absolute numbers reduced by at least 0.2–0.9% and geographical ranges shrinking by 1–2.3 % compared to their historical levels in the mid-1950s. The current situation provides grounds for a negative forecast for the next few decades.