{"title":"Locomotor Activity Rhythm under Natural Conditions and the Effect of Temperature on the Rhythm in the Band-Legged Ground Cricket, <i>Dianemobius nigrofasciatus</i>.","authors":"Satoshi Fujita, Jun Endo, Hideharu Numata","doi":"10.2108/zs250039","DOIUrl":"https://doi.org/10.2108/zs250039","url":null,"abstract":"<p><p><i>Dianemobius nigrofasciatus</i> (Orthoptera: Trigonidiidae) shows a circadian rhythm in locomotor activity. In the present study, we recorded the locomotor activity of male adults under naturally fluctuating temperature and light conditions over a long period in both summer and autumn. The results showed that the onset time of locomotor activity was later on warmer days in summer, and the cessation time was earlier on cooler days in autumn. The delay in the onset time was also observed under laboratory conditions when a high temperature was added in the late photophase. When the high temperature period was removed, the onset of activity immediately returned to the original time of day. Thus, the high temperature did not alter the circadian phase but directly suppressed locomotor activity through a masking effect.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 6","pages":"581-586"},"PeriodicalIF":1.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145688288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Morphological Alterations in <i>Rana japonica</i> Tadpoles Induced by Predation Risk From <i>Hynobius setouchi</i> Salamander Larvae.","authors":"Kazunori Matsumoto, Maika Ueda","doi":"10.2108/zs250026","DOIUrl":"https://doi.org/10.2108/zs250026","url":null,"abstract":"<p><p>Anuran tadpoles demonstrate morphological alterations in response to predation risk, thereby developing predator-specific defensive morphologies that enhance survivorship, compared to tadpoles without such defenses. In aquarium experiments, we assessed whether <i>Rana japonica</i> tadpoles demonstrated morphological changes when exposed to the salamander larvae <i>Hynobius setouchi</i>. They are gape-limited predators that coexist with these tadpoles in natural environments. In the presence of <i>H. setouchi</i> larvae, some <i>R. japonica</i> tadpoles were swallowed tail-first, and smaller individuals demonstrated damaged tail fins because of predator attacks, whereas larger tadpoles had intact tail fins. Tadpoles developed larger body sizes and deeper tail fins only when they were in close proximity to <i>H. setouchi</i> larvae, and smaller tadpoles demonstrated relatively larger tail-to-body ratios. These results imply that larger body sizes and deeper tail fins serve as inducible defense mechanisms, potentially improving swimming ability to evade predators and reducing the likelihood of tail-first ingestion.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 6","pages":"556-564"},"PeriodicalIF":1.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145688316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Early Gonadal Differentiation in the Viviparous Red Stingray: Histological Characterization of Sexual Dimorphism.","authors":"Yasuhisa Kobayashi, Naoaki Tsutsui, Tatsuya Sakamoto","doi":"10.2108/zs250013","DOIUrl":"https://doi.org/10.2108/zs250013","url":null,"abstract":"<p><p>The mechanisms underlying sexual differentiation in viviparous chondrichthyans remain poorly understood, particularly regarding the impact of the maternal environment on early gonadal differentiation. In this study, we examined gonadal and reproductive duct differentiation in red stingray (<i>Hemitrygon akajei</i>) embryos before and after clasper formation through detailed histological analyses. Histological observations revealed that early embryos (stage 3, before clasper formation) exhibited undifferentiated gonads with scattered primordial germ cells, whereas later embryos (stage 4, during clasper development) exhibited clear sexual dimorphism. Female gonads contained numerous germ cells localized in the dorsal region, whereas male gonads contained fewer scattered germ cells. Both the Müllerian and Wolffian ducts were present in both sexes, with the Wolffian ducts emerging from the Müllerian ducts in a segmental pattern. Stage 4 female embryos exhibited a selective enlargement of the right Müllerian duct, establishing reproductive tract asymmetry. The sex ratio of red stingray embryos was 1:1. These findings provide the first detailed histological characterization of gonadal differentiation and reproductive duct development in a viviparous chondrichthyan and establish an essential foundation for future studies on sexual development in these evolutionarily significant vertebrates.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"446-452"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Morphological and Molecular Characteristics of <i>Longicollum alemniscus</i> (Acanthocephala: Echinorhynchida), with a Taxonomic Revision of the Genus <i>Longicollum</i>.","authors":"Yuki Kita, Hakuyu Sekine, Wataru Nagata, Reina Doi, Tsukasa Waki, Hiroshi Kajihara","doi":"10.2108/zs250028","DOIUrl":"https://doi.org/10.2108/zs250028","url":null,"abstract":"<p><p>The acanthocephalan genus <i>Longicollum</i> Yamaguti, 1935 currently comprises 12 fish-parasitic species. Except for <i>L. pagrosomi</i> Yamaguti, 1935, the remaining 11 congeners have not been the subject of molecular phylogenetic studies. <i>Longicollum alemniscus</i> (Harada, 1935) has been found in brackish and marine fish in Taiwan and Japan, but its morphology remains inadequately understood. In this paper, we provide a morphological redescription and infer the phylogenetic position of <i>L. alemniscus</i> within the Pomphorhynchidae. Furthermore, we summarize the morphological characteristics of <i>Longicollum</i> to distinguish it from the morphologically similar genus <i>Paralongicollum</i> Amin, Bauer, and Sidorov, 1991.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"484-491"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Defensive and Offensive Behavioral Interactions between Shelter-Building Caterpillars and Hunting Wasps.","authors":"Misaki Tsujii, Shinji Sugiura","doi":"10.2108/zs250027","DOIUrl":"https://doi.org/10.2108/zs250027","url":null,"abstract":"<p><p>Many animals build shelters to avoid predation, but some predators cope with these shelters to prey on them. To explore the behavioral interactions between shelter-building prey and their predators, we investigated the shelter defenses of two caterpillar species (Lepidoptera: Crambidae) and the hunting behavior of each predator species (Hymenoptera: Vespidae: Eumeninae) under laboratory conditions. Female wasps of <i>Anterhynchium flavomarginatum</i> and <i>A</i>. <i>gibbifrons</i> were observed attacking the larvae of <i>Haritalodes derogata</i> and <i>Demobotys pervulgalis</i> (Lepidoptera: Crambidae), which construct open and closed leaf shelters, respectively. The attack behaviors differed between the two wasp species. <i>Anterhynchium flavomarginatum</i> employed two attack strategies: (I) boring holes in shelters and driving caterpillars out, and (II) invading shelters and searching for prey inside. In contrast, <i>A</i>. <i>gibbifrons</i> utilized a single strategy: cutting the silk threads binding the leaves with their mandibles to open the shelters and search for prey inside. Approximately half of the prey caterpillars could avoid predation; the shelter morphology and behavior of each caterpillar species likely contributed to evading the wasps. Each caterpillar species may have adapted a specific anti-wasp defense, while each wasp species may have acquired offensive traits to overcome the defense of each prey.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"435-445"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mizuho Munakata, Hayato Tanaka, Ko Tomikawa, Yoshimi Kawasaki, Alfonso Miranda, Nilton Deza, Keiichi Kakui
{"title":"Description and Phylogenetic Position of <i>Thermocypris isabella</i> gen. et sp. nov. (Ostracoda: Cyprididae: Cyprinotinae) from a Hot Spring in Peru.","authors":"Mizuho Munakata, Hayato Tanaka, Ko Tomikawa, Yoshimi Kawasaki, Alfonso Miranda, Nilton Deza, Keiichi Kakui","doi":"10.2108/zs240090","DOIUrl":"https://doi.org/10.2108/zs240090","url":null,"abstract":"<p><p>During a faunal survey in Baños del Inca hot spring (40-50°C), Cajamarca, Peru, we collected a cyprinotine ostracod species, the sixth example of a thermophilic ostracod inhabiting freshwater in temperatures above 40°C. Because this could not be assigned to any of nine genera in Cyprinotinae, we established the new genus <i>Thermocypris</i> for it and described it as <i>Thermocypris isabella</i> gen. et sp. nov., defined by the following combination of characters: (1) no dorsal hump on carapace, (2) no tubercles on either valve, (3) left valve slightly overlapping right valve along all margins, (4) no selvage on anterior part of right valve, (5) only seta d1 on first podomere of 6th limb, (6) only two shields (medial and lateral) on hemipenis, and (7) medial shield unilobed and lateral shield tooth-shaped. We determined partial sequences for the mitochondrial cytochrome <i>c</i> oxidase subunit I (COI) and nuclear 18S and 28S rRNA genes from a specimen of the new species. In a maximum likelihood tree based on 18S + 28S, <i>T. isabella</i> was the sister taxon to <i>Heterocypris chetumalensis</i> (Yoo, Cohuo, Macario-Gonzalez, and Karanovic, 2017), with high branchial support. A clade including Cyprinotinae (<i>Cyprinotus</i> Brady, 1868 + <i>Heterocypris</i> Claus, 1892 + <i>Thermocypris</i>) and Eucypridinae (<i>Eucypris</i> Vavra, 1891) was fully supported; our phylogeny showed <i>Heterocypris</i> not to be monophyletic.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"510-520"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Regulation of Reproduction and Swimming Ability in the Male Marsh Rice Rat (<i>Oryzomys palustris</i>).","authors":"Kent Edmonds","doi":"10.2108/zs240114","DOIUrl":"https://doi.org/10.2108/zs240114","url":null,"abstract":"<p><p>Photoperiod and melatonin regulate reproduction in mammals. The rice rat (<i>Oryzomys palustris</i>) is reproductively photoperiodic and on a long photoperiod responds to melatonin administration with inhibited reproduction. I examined whether photoperiod, melatonin, and the removal of gonadal steroids via castration affected growth, reproduction, pelage, and swimming ability. Juvenile males were housed on 14L:10D or 11L:13D and at 68 days of age rice rats were weighed, allowed to swim for 10 minutes while being videotaped to quantify swimming and floating times, and then reweighed. One day later, these rice rats were euthanized and the testes, seminal vesicles (SV), Harderian glands (HG), and spleen were weighed. The shorter photoperiod significantly decreased body, testes, SV, and HG masses only. The pelage of rice rats absorbed more water on 14L:10D than on 11L:13D, despite no difference in pelage lengths. Melatonin implants decreased body mass, the masses of the testes, SV, and HG, and pelage water absorption, but increased pelage length. Lastly, castration decreased SV and HG masses, but increased body and spleen masses. Swimming and floating times were not affected by any treatment. Taken together, these results show that all treatments affected growth and reproduction in rice rats, but did not affect swimming ability. Thus, the physiological changes characteristic of winter are not sufficient to alter aspects of swimming ability as swimming ability appears to be independent of reproductive condition.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"471-477"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ascidian Larvae Prefer Hydrophobic Substrates for Settlement.","authors":"Noburu Sensui, Euichi Hirose","doi":"10.2108/zs250022","DOIUrl":"https://doi.org/10.2108/zs250022","url":null,"abstract":"<p><p>The selection of settlement sites by larvae is a crucial event in the life cycle of sessile animals, as they are usually unable to migrate after settlement and metamorphosis into sessile forms. For example, some species prefer hydrophilic substrates, whereas others prefer hydrophobic substrates. Understanding larval preferences for substrates will provide an essential basis for controlling biofouling. In this study, we focused on the water wettability of substrates for settlement and investigated larval substrate preference in three ascidian species, <i>Phallusia philipinennsis</i>, <i>Ascidia sydneiensis</i>, and <i>Ciona robusta</i> (= <i>C. intestinalis</i> type A), using a four-choice assay with substrates of different water wettability (contact angle of a water droplet): silicone rubber (115°), polyvinyl chloride (80°), glass (31°), and hydrophilic film SH2CLHF (14°). In some regions of the world, <i>A. sydneiensis</i> and <i>C. robusta</i> are often noted as invasive species and are serious biofoulants. In all three species, larvae showed a significant preference for more hydrophobic substrates, and none settled on the most hydrophilic substrate, that is, SH2CLHF. It is difficult to explain why ascidian larvae prefer a more hydrophobic substrate, since hydrophobic materials, such as silicon, are often used as antifouling measures. This inconsistent substrate preference can be applied to mitigate biofouling.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"478-483"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhuo-Ni Chen, Shi-Xiong Leng, Chun-Sheng Yang, Xian-Wu Tang, Bin Qiu, Tong-Xiang Zou
{"title":"A New Freshwater Fish Species of the Genus <i>Oreonectes</i> (Teleostei: Cypriniformes: Nemacheilidae) From Guangxi, China.","authors":"Zhuo-Ni Chen, Shi-Xiong Leng, Chun-Sheng Yang, Xian-Wu Tang, Bin Qiu, Tong-Xiang Zou","doi":"10.2108/zs240109","DOIUrl":"https://doi.org/10.2108/zs240109","url":null,"abstract":"<p><p>We describe a new species of loach, <i>Oreonectes daguishanensis</i> sp. nov. from Guangxi Daguishan Crocodile Lizard National Reserve in Hezhou City, Guangxi Zhuang Autonomous Region, China. Morphologically, the new species can be distinguished from congeneric species by the following combination of characters: dorsal-fin origin posterior to pelvic-fin origin; pectoral fins short, not reaching pelvic-fin base; pelvic-fin tip does not exceed anus; body width 10.2%-13.6% of standard length; eye diameter 15.5%-19.3% of head length; posterior chamber of swim bladder degenerated. Phylogenetic analysis of the mitochondrial cytochrome <i>c</i> oxidase subunit I and cytochrome <i>b</i> gene markers supports its species-level distinctiveness, with uncorrected <i>p</i>-distances ranging from 7.4% to 9.7% from closest relatives.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"498-509"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Degeneration of Comb Plates during Larval Stages in a Sessile Platyctenid Ctenophore, <i>Lyrocteis imperatoris</i> (Ctenophore, Platyctenida).","authors":"Ryosuke Kimbara, Shinya Yamauchi, Hisanori Kohtsuka, Toru Miura","doi":"10.2108/zs240104","DOIUrl":"https://doi.org/10.2108/zs240104","url":null,"abstract":"<p><p>In species belonging to the phylum Ctenophore, comb plates consisting of bundles of multiple cilia are a characteristic synapomorphy and are essential for active swimming. However, in most species of the order Platyctenida, even though pelagic larvae have comb plates, adults completely lose comb plates and exhibit a sessile lifestyle. To understand the evolution of platynectids' unique lifestyles, it is necessary to reveal how comb plates are lost during the larval stages. Therefore, in this study, to reveal the process of comb plate degeneration, histological observations on larvae of different post-hatching ages were carried out in the harp comb jelly, <i>Lyrocteis imperatoris</i> (Platyctenida: Lyroctenidae). The observations showed that the number of comb plates decreased along with the larval growth, and they completely disappeared before the larvae settled down. Also, it was shown that the sizes of the ribs (rows of comb plates) in larvae increased until around 30 days after hatching, while relative sizes of ribs with respect to larval body sizes continued to get smaller after hatching. This suggested that, in <i>L. imperatoris</i>, although the ability to disperse away from their parents would be maintained after hatching as long as ribs develop, this ability would significantly decrease after the cessation of rib development. Therefore, in contrast to pelagic comb jellies in which ribs continue to develop throughout their lives, <i>L. imperatoris</i> acquired mechanisms to cease rib development and promote rib degeneration during their post-hatching growth, which are involved in the evolution of novel sessile lifestyles.</p>","PeriodicalId":24040,"journal":{"name":"Zoological Science","volume":"42 5","pages":"453-462"},"PeriodicalIF":1.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145253159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}