Zoological Studies最新文献

In this study, we present descriptions of two new species of the genus Mesobiotus discovered in the tropical rainforest of Kibale National Park in Uganda, the first new tardigrade species from this location. Our research utilized morphological data obtained with phase-contrast and scanning electron microscopes and DNA sequences of four genetic markers (28S rRNA, 18S rRNA, CO1 and ITS-2). The main character distinguishing the new species, Mesobiotus ugandicus sp. nov., is the presence of egg processes in the shape of wide cones without filaments. The second new species Mesobiotus krystynae sp. nov. is distinguished mainly by having egg processes with long, slender endings with short filaments. However, both new species are properly differentiated from phenotypically similar species of the Mesobiotus harmsworthi morpho-group by morphological and morphometric details of animals and eggs. The genetic data allowed us also to conduct a phylogenetic analysis, which elucidated positions of the new taxa and extended our understanding of the relationships within the genus.

A new ribbon worm, Tetrastemma luteum sp. nov., reported from Japanese waters, is described using morphological and DNA sequence data based on 15 specimens-10 from Oshoro, 2 from Otsuchi, and 3 from Sugashima-all associated with brown algae in the family Sargassaceae. The new species is characterized by its entirely yellowish body; a rounded, notched, and knobbed head that is similarly coloured to (or lighter than) the body; brown-orange, more indented anterior and bright-orange posterior ocelli; a central stylet shorter than the stylet basis; ventrolateral, non-connected anterior cephalic furrows that are not visible in dorsal view; and a posterior cephalic furrow encircling the head. Tetrastemma luteum sp. nov. exhibits variation in the degree of its body colouration, body and head pigmentation patterns, head shape, stylet basis shape, and number of accessory stylets. Additionally, we report a new locality, Oshoro, for Tetrastemma phaeobasisae Kulikova, 1987, based on a single specimen, representing the first record of this species in Japan. This species was previously known to be distributed only in Vostok Bay and Peter the Great Bay, Russia. Its occurrence in Oshoro is confirmed both by morphology and DNA sequence. Furthermore, we tested the phylogenetic positions of T. luteum sp. nov. and T. phaeobasisae within the genus Tetrastemma Ehrenberg, 1828 using newly determined 16S, 18S, and 28S ribosomal RNA, cytochrome c oxidase subunit I, and histone H3 gene sequences. Our phylogenetic analyses confirmed the genus placement of T. luteum sp. nov. being nested within the Asian-Australia Pacific subclade of the genus together with T. phaeobasisae. The new species is a sister taxon to the clade consisting of Tetrastemma pseudocoronatum Chernyshev, 1998 and T. phaeobasisae.

The taxonomy and biogeography of Neocaridina species in Japan remain complex and contested. In a recent commentary, Fuke (2024) criticized the conclusions of Shih et al. (2024), challenging their species delineations and argues that such taxonomy directly conditions interpretations of native versus introduced lineages. As the first two authors of Shih et al. (2024), we agree that accurate identification is essential for conservation of native taxa, but we contend that several of Fuke's inferences reflect misreadings of both morphological and genetic data. In this reply, we address these misinterpretations, clarify our taxonomic conclusions, and reassess phylogenetic and population genetic evidence. Our findings suggest that N. denticulata and N. davidi can be consistently distinguished using integrated molecular and morphological criteria, in contrast to Fuke's claim of conspecificity. We also emphasize the limitations of relying solely on mitochondrial DNA or SNP admixture patterns for species delimitation, particularly in hybridizing lineages. Finally, we advocate for integrative, evidence-based taxonomy as the best approach to resolving species boundaries and supporting conservation of cryptic native species of Neocaridina.

Tachaea chinensis Thielemann, 1910 is a species of ectoparasitic isopod that infests freshwater shrimps and prawns. Individuals are often found attached to the side of their host shrimp's carapace. Despite the limited space for attachment there, records indicate that several isopods can infest a single host shrimp simultaneously. There are limited data, however, on the prevalence of such occurrences and their potential effect on host survival. Here, we report on the occurrence of multiple infestation by T. chinensis on the freshwater shrimp Palaemon paucidens De Haan, 1844 in Izumo, Shimane Prefecture, Japan, during April and May of 2018 and 2019. The prevalence of infested shrimp was higher (80.0-90.2%) at St. 1, a semi-closed spillway that alternates between continuous water flow and isolated stagnancy, than at St. 2 (45.0-55.0%), an open stream with year-round continuous water flow. The number of parasites per host was zero to nine at St.1 and zero to three at St. 2. A significant positive correlation was observed between the prevalence of isopods on shrimp and the mean number of these parasites per host. In a laboratory experiment in which individual shrimp of three size groups were reared for seven days with different numbers of isopods from three matching size groups, the survival rate of hosts was 100% with one T. chinensis, 90-100% with two, 50-80% with four, and 10-40% with eight. These results suggest that the presence of two or more parasites negatively affects the hardiness of the host, increasing shrimp mortality and potentially reducing their density in nature, especially in semi-closed habitats. This has obvious implications for shrimp farms, which should strive to prevent the entry of this isopod into their water systems.

The Taiwan Broad-tailed Swallowtail, Papilio maraho, is an endangered species in Taiwan and has been recognized as sister to continental Papilio elwesi. However, the exact species identification between them has remained contentious because of similar genital morphology and only a few DNA diagnostic sites. Here, we integrate wing morphometrics and next-generation sequencing to reevaluate their identification. Our analyses show that hindwing morphology clearly separates these taxa: Papilio maraho has a broader, shorted hindwing with a much higher proportion of red scaling, whereas Papilio elwesi shows a narrower, elongated hindwing with higher proportion of black scaling. Furthermore, phylogenetic relationships and the haplotype network based on 37 mitochondrial genes separates the two taxa into reciprocally monophyletic clusters, further confirming their genetic distinctiveness. The congruence among morphological and genetic evidences strongly supports that Papilio maraho is an independent lineage. Formal recognition at the species level will facilitate more targeted and effective conservation strategies.

Dorylaimellus (Dorylaimellus) grandis sp. nov. is described, including morphological data, LM and SEM illustrations, and molecular (18S-, 28S-rDNA) analyses. The new taxon is widely distributed in the southern part of the Iberian Peninsula, where it is mainly associated with natural habitats. It is characterized by its 1.57-2.43 mm long body, lip region cap-like and offset by marked constriction, cheilostom slightly flasklike with thick and visibly refractive walls bearing distinct circumoral platelets, odontostyle 9.0-9.5 μm long or almost equal to lip region diameter, odontophore linear, relatively short neck (b = 6.1-9.7), anterior pharyngeal region weakly muscular and bearing a spindle-shaped and valve containing region behind the odontophore base, pharyngeal expansion 113-157 μm long or 44-54% of total neck length, longitudinal vulva (V = 5057), tail conoid to subcylindroid (31-47 μm, c = 37-59, c' = 1.4-1.9 in females), spicules 38-40 μm, and five ventromedian supplements with hiatus. The results confirm an intricate scenario for elucidating both the phylogeny and the taxonomy of Dorylaimellinae in particular, and of Belondiridae in general. The morphological heterogeneity of the group is even more complex than usually assumed, and its internal evolutionary relationships are not well established as the phylogenies derived from the molecular analyses significantly differ depending on the gene considered.

Parasites can significantly influence ecological communities by altering the traits of their hosts. hizocephalans, a group closely related to thoracican barnacles within Cirripedia, are common in marine ecosystems and profoundly impact their hosts, most notably by inducing reproductive castration. However, their influence on other host traits, particularly those related to predator defense, remains underexplored. The rhizocephalan Polyascus polygenea modifies the length of the cheliped propodus in the host crab Hemigrapsus sanguineus. To determine whether parasitized crabs are more vulnerable to predation, we conducted field tethering experiments comparing parasitized and unparasitized individuals. The results showed that parasitism itself did not directly increase the likelihood of crabs being lost (presumably due to predation) in either sex. However, structural equation modeling revealed that in parasitized males, a reduced cheliped propodus length indirectly increased predation risk. In females, parasitism reduced carapace width, which in turn shortened the cheliped propodus and increased vulnerability to predation. These findings demonstrate that Polyascus infection heightens predation risk through non-consumptive effects by inducing host morphological changes.

Clinostomum species are typical trematodes (or flatworms) and zoonotic parasites of humans, fish, and birds. These parasites require at least two definitive hosts, fish and birds, to complete their life cycle. Previous studies indicated that the yellow grub, identified as C. complanatum, first appeared in northern Taiwan around the 1990s, with uncertain origins. This study identified 65 of 2,181 museum fish specimens with leech-like metacercariae across four main river systems (Tamshui, Houlong, Tzengwen, and Xiuguluan Rivers) and documented new infection records in fishes from Beigang, Puzih, Kaoping, and Bie Rivers during subsequent field work. The parasite appears to have established in the Houlong and Tamshui Rivers before dispersing to southern and eastern waterways. COI barcode analysis revealed that most metacercariae belong to C. sinensis with low nucleotide diversity (π = 0.00314353). The closely related haplotypes with insignificant Tajima's D (-1.89473 with p-value = 0.981839) suggest a gentle population expansion after their colonization to Taiwan. Additionally, yellow grub infections were more prevalent in carnivorous fishes (> 60%) compared to omnivorous and algal-feeding fishes. The high infection rates documented in literature and museum specimens suggest that Jhonggang and Houlong rivers represent the primary (or earlier) infection areas from which the parasite subsequently spread throughout Taiwan, highlighting the need for enhanced regulations to protect endangered or cultivated species.

Asopinae is a globally distributed subfamily of Pentatomidae, encompassing 65 genera and over 300 known species. Most asopines are generalist predators, making them valuable for the biological control of agricultural pests. Although the subfamily has a wide global range, most genera are region-specific. To date, no database has consolidated collection sites or provided organized, updated distributional records for these predatory stink bugs. Here, we aim to build a web interactive database after compiling distribution data for Asopinae species across all continents except Antarctica, using taxonomic revisions, regional lists, catalogues, and specimen collections. Our study also examines global patterns of taxonomic richness using multiple analytical units, including political boundaries, biogeographic realms, ecoregions, and grid cells. The resulting database of 5,831 records for 299 species is now available on the "Asopinae of the World Database," an interactive, live website. Results indicate that the most species-rich countries are predominantly the world's largest, with the exception of nations characterized by high proportions of deserts or extreme environments. Species richness across ecoregions exhibits discontinuous patterns, even between adjacent areas. Among biogeographic realms, the Neotropics host the highest richness, followed by Indo-Malay, Palearctic, Afrotropic, Nearctic, and Australasian regions. Furthermore, we identified 23 bioregions that align closely with classical biogeographical realms, and we recognized 14 key areas of endemism within the group. The extensive data presented in this study offer a valuable resource for future systematic, taxonomic, biological, and applied research on Asopinae.