Seishi Kimura

Size‐Dependent Male Alternative Reproductive Tactics in the Shell‐Brooding Cichlid Fish Lamprologus callipterus in Lake Tanganyika

Reproductive parasitism among males is prevalent in fishes. Typically, small ripe males parasitize the reproductive effort of large bourgeois males by using various behavioural tactics. We examined the size-dependent advantages of parasitic behavioural tactics in a shell-brooding cichlid fish of Lake Tanganyika with three male types (large bourgeois males and medium–dwarf parasitic males). The extremely small dwarf males weighing only 2.5% on average of large males, perform a specialized tactic in which they avoid attacks by the resident large males by entering the inner part of the whorl of the shell where a female is spawning. Field observations and a manipulation experiment revealed that the very small size of dwarf males is essential for utilizing this positional advantage. Larger dwarf males and medium males opportunistically adopt darting and sneaking which likely result in very low reproductive outcomes. The size associated advantage and disadvantage of parasitic tactics are the major factors shaping the size distribution of ripe males in this species. The success of parasitic spawning by dwarf males is determined not only by body size of the males, but also by the relative sizes of females and shells in which they spawn. These factors would affect the choice of different tactics among dwarf males. The analyses of body condition among ripe and unripe males across a wide range of body sizes suggested that onset of sexual activities at very small body sizes in dwarf males may be associated with higher condition factors that is a pre-requisite for maintaining investment in testes and intense reproductive activities.

Phylogenetic diversity and cosymbiosis in the bioluminescent symbioses of "Photobacterium mandapamensis".

ABSTRACT “Photobacterium mandapamensis” (proposed name) and Photobacterium leiognathi are closely related, phenotypically similar marine bacteria that form bioluminescent symbioses with marine animals. Despite their similarity, however, these bacteria can be distinguished phylogenetically by sequence divergence of their luminescence genes, luxCDAB(F)E, by the presence (P. mandapamensis) or the absence (P. leiognathi) of luxF and, as shown here, by the sequence divergence of genes involved in the synthesis of riboflavin, ribBHA. To gain insight into the possibility that P. mandapamensis and P. leiognathi are ecologically distinct, we used these phylogenetic criteria to determine the incidence of P. mandapamensis as a bioluminescent symbiont of marine animals. Five fish species, Acropoma japonicum (Perciformes, Acropomatidae), Photopectoralis panayensis and Photopectoralis bindus (Perciformes, Leiognathidae), Siphamia versicolor (Perciformes, Apogonidae), and Gadella jordani (Gadiformes, Moridae), were found to harbor P. mandapamensis in their light organs. Specimens of A. japonicus, P. panayensis, and P. bindus harbored P. mandapamensis and P. leiognathi together as cosymbionts of the same light organ. Regardless of cosymbiosis, P. mandapamensis was the predominant symbiont of A. japonicum, and it was the apparently exclusive symbiont of S. versicolor and G. jordani. In contrast, P. leiognathi was found to be the predominant symbiont of P. panayensis and P. bindus, and it appears to be the exclusive symbiont of other leiognathid fishes and a loliginid squid. A phylogenetic test for cospeciation revealed no evidence of codivergence between P. mandapamensis and its host fishes, indicating that coevolution apparently is not the basis for this bacteriums host preferences. These results, which are the first report of bacterial cosymbiosis in fish light organs and the first demonstration that P. leiognathi is not the exclusive light organ symbiont of leiognathid fishes, demonstrate that the host species ranges of P. mandapamensis and P. leiognathi are substantially distinct. The host range difference underscores possible differences in the environmental distributions and physiologies of these two bacterial species.

The Leiognathus splendens complex (Perciformes: Leiognathidae) with the description of a new species, Leiognathus kupanensis Kimura and Peristiwady

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes the Leiognathus splendens complex comprising four valid species: L. jonesi James, 1971, widely distributed in the Indo-West Pacific, from Mauritius to Papua New Guinea, north to Hainan I. (China), and south to Brisbane, Australia; L. kupanensis sp. nov., currently known only from Kupang, Timor, Indonesia; L. rapsoni Munro, 1964, currently known only from India, Indonesia, and Papua New Guinea, and L. splendens Cuvier, 1829, widely distributed in the eastern Indian and western Pacific oceans, from India to Papua New Guinea, and from southern Japan to northern Australia. The L. splendens complex can be defined by the following combination of characters: body depth 42–60% of standard length; mouth protruding downward; slender, minute teeth uniserially on jaws; lower margin of orbit above the horizontal through the gape when mouth closed; breast almost completely scaled; lateral line complete, and a dark blotch on top of spinous dorsal fin. Diagnostic characters of the members are as follows: L. jonesi—anterior dorsolateral body surface with a semicircular naked area on nape, and a paler dark blotch on spinous dorsal fin; L. kupanensis—anterior dorsolateral body surface widely naked; L. rapsoni—cheek scaled; L. splendens—anterior dorsolateral body surface completely scaled and a jet black blotch on spinous dorsal fin.

The Leiognathus aureus complex (Perciformes: Leiognathidae) with the description of a new species

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes a complex comprising three valid species: Leiognathus aureus Abe and Haneda, 1972, widely distributed in the western Pacific Ocean (Taiwan, Philippines, Thailand, Singapore, Indonesia, and northern Australia); L. hataii Abe and Haneda, 1972, currently known only from Ambon, Indonesia; and L. panayensis sp. nov. Kimura and Dunlap, currently known only from Panay Island, the Philippines. The L. aureus complex can be defined by the following combination of characters: mouth protruding forward, not downward; small but sharp conical teeth uniserially on jaws; a black line between lower margin of eye and lower jaw articulation; and lateral line incomplete, ending below posterior part of dorsal fin base or on anterior caudal peduncle. Leiognathus hataii differs from both L. aureus and L. panayensis in having a large dark blotch below the spinous dorsal fin base and fewer counts of scales (lateral line scales 50–58 vs. 64–85 in the latter two species; scales above lateral line 7–10 vs. 12–18; scales below lateral line 22–26 vs. 30–41). Leiognathus panayensis is distinguished from L. aureus in having a deeper body (41–51% SL vs. 35–45% SL in the latter), long posterior limb of maxilla (21–25% HL vs. 15–23% HL), wholly scaled belly (vs. naked along preanal median keel), and a dark blotch on nape (vs. absent).

Revision of the genus Nuchequula with descriptions of three new species (Perciformes: Leiognathidae)

The leiognathid genus Nuchequula can be defined by the following combination of characters: mouth protruding downward; a narrow band of small, slender, villiform teeth in both jaws; teeth on upper jaw strongly recurved; the lateral line almost complete; a dark blotch on the nape. Although the genus was first established as a subgenus of Eubleekeria, it is here raised to generic level on the basis of the aforementioned morphological characters and recent molecular biological evidence. The genus comprises six valid species: N. blochii (Valenciennes 1835), distributed in India and Thailand; N. flavaxilla sp. nov., occurring only at Panay I., Philippines; N. gerreoides (Bleeker 1851), widely distributed in the Indo-West Pacific, from the Persian Gulf to Cape York, Australia, and north to Taiwan; N. glenysae sp. nov., from northern Australia and Ambon, Indonesia; N. longicornis sp. nov., from the Gulf of Thailand and Indonesia; and N. nuchalis (Temminck and Schlegel 1845), occurring in southern China including Taiwan, and southern Japan. Diagnostic characters of the species belonging to the genus are as follows: N. blochii—breast scaled, cheek naked, and a conspicuous black blotch distally on spinous dorsal fin; N. flavaxilla sp. nov.—breast naked, dorsolateral body surface fully scaled, preorbital spine bicuspid and not expanded distally, and second dorsal and anal fin spines conspicuously elongated; N. gerreoides—breast naked, anterior part of dorsolateral surface of body almost completely scaled, and second dorsal and anal fin spines not conspicuously elongated; N. glenysae sp. nov.—breast completely scaled, cheek scaled, and unique complicated sensory canals present on the suborbital area, extending to the nape; N. longicornis sp. nov.—breast naked, dorsolateral body surface fully scaled, preorbital spine bicuspid or tricuspid and extended distally, and second dorsal fin spines only conspicuously elongated; N. nuchalis—breast naked, anterior part of dorsolateral surface of body widely naked, and a conspicuous dark blotch distally on spinous dorsal fin.

Eubleekeria Fowler 1904, a valid genus of Leiognathidae (Perciformes)

The genus Eubleekeria (type species, Equula splendens Cuvier 1829) was established by Fowler (1904) as a subgenus of Leiognathus Lacepede 1802, characterized by mouth downward-protruding, breast and chest entirely scaled, and lateral line completed. He included two species, Leiognathus splendens (Cuvier 1829) and Leioganthus spilotus Fowler 1904 (synonymized under L. splendens by Kimura et al. 2005) in the subgenus. Subsequently, Whitley (1932) raised the subgenus Eubleekeria to a genus composed of two species, Eubleekeria ovais (De Vis 1884) (synonymized under L. splendens by Kimura et al. 2005) and Eubleekeria nuchalis (Temminck and Schlegel 1845). Later, however, James (1978) synonymized the genus under Leiognathus and Jones (1985) did not accept the subgenus Eubleekeria. Recently, Kimura et al. (2005) established the L. splendens complex, including Leiognathus jonesi James 1971, Leiognathus kupanensis Kimura and Peristiwady in Kimura et al. 2005, Leiognathus rapsoni Muro 1964, and L. splendens, based on taxonomic analysis of a group of morphologically similar leiognathid species. The complex is clearly distinguishable from other complexes of Leiognathus or genera of Leiognathidae by external morphology, i.e., eyes located above gape, scaled breast, completed lateral line, a black blotch on dorsal fin, etc., as stated below (as diagnosis of Eubleekeria). In polygenetic analysis among 14 species of Leiognathidae, inferred from two mitochondrial genes, by Ikejima et al. (2004), L. jonesi, reported as L. splendens [the voucher specimen, NSMT-P 62518 (National Museum of Nature and Science, Tokyo), was re-identified by the first author] was placed as a member of a clade consisting of genera Gazza Ruppell 1835 and Secutor Gistel 1848, while all other species of Leiognathus [except Leiognathus equulus (Forsskal 1775), being placed as a basal of all leiognathids] comprised a clade with a sister relationship to the former. Sparks et al. (2005) also reported that L. splendens consisted of a clade with genera Photopectoralis Sparks, Dunlap, and Smith 2005 [member of the genus not included in the analysis by Ikejima et al. (2004)], Gazza, and Secutor, based on seven mitochondrial and two molecular genes. Further, L. jonesi is placed as a sister species of L. splendens in the phylogenetic tree based on two mitochondrial genes (Sparks and Dunlap 2004). Therefore, these genetic facts as well as the morphological features of the L. splendens complex strongly support that the complex should be recognized as a genus separate from Leiognathus. Eubleekeria, based on Equula splendens as a type species, is justified as a name that is applicable to the genus because there are no other genus group names based on the other congeners.

Redescriptions of the Indo-Pacific atherinid fishes Atherinomorus forskalii, Atherinomorus lacunosus, and Atherinomorus pinguis

The Indo-Pacific marine atherinid fishes Atherinomorus forskalii (Rüppell, 1838), Atherinomorus lacunosus (Forster, 1801), and Atherinomorus pinguis (Lacepède, 1803) are redescribed as valid species based on the types and non-type specimens collected throughout the Indo-Pacific. They are similar to each other chiefly in having a wide midlateral band (almost the same or greater than the midlateral scale width), large mouth (posterior tip of upper jaw reaching to or beyond a vertical through anterior margin of pupil), and no distinct tubercle at the posterior end of the dentary. All three species are distinguishable from congeners by those characters. The three species have long been confused with each other or synonymized erroneously as a single species. Atherinomorus forskalii, known from the Red Sea and eastern Mediterranean, differs from Atherinomorus lacunosus and Atherinomorus pinguis in having conspicuous, large endopterygoid teeth, forming obvious tooth ridges. Atherinomorus lacunosus, widely distributed in almost the entire Indo-Pacific, from East Africa to Tonga, north to southern Japan, and south to northern Australia, differs from Atherinomorus pinguis in having a wider midlateral band (the lower margin reaching to almost the center of the fourth scale row at level of the anal fin origin vs. the lower margin reaching to the ventral end of the third scale row in Atherinomorus pinguis) and more numerous midlateral scales (40–44 vs. 38–41 in Atherinomorus pinguis). Atherina morrisi Jordan and Starks, 1906, Hepsetia pinguis mineri Nichols and Roemhild, 1951, Pranesus capricornensis Woodland, 1961, Pranesus maculatus Taylor, 1964, and Pranesus pinguis ruppelli Smith, 1965, are regarded as junior synonyms of Atherinomorus lacunosus. Atherinomorus pinguis is also widely distributed in the Indo-West Pacific, from East Africa to northern Australia and north to southern Japan. Atherina pectoralis Valenciennes, 1835, is considered a junior synonym of Atherinomorus pinguis.

Developmental morphology of the cyprinid fish Tanichthys albonubes

Embryonic, larval, and juvenile development of a small cyprinid species, Tanichthys albonubes, is described from laboratory-reared specimens. The eggs, measuring 1.0–1.2u2009mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yolk without oil globules. Hatching occurred 45–53u2009h after fertilization at 25.5°–26.9°C. The newly hatched larvae, measuring 2.2–2.6u2009mm in body length (BL), had melanophores on the head and body. In particular, a dark vertical streak occurring posterior to the otic capsule and melanophores above the eyes were distinctive. The yolk was completely absorbed at 3.4u2009mm BL. Notochord flexion was initiated at 5.0u2009mm BL and finished at 6.0u2009mm BL. Aggregate numbers of all fin rays were completed at 11u2009mm BL. Squamation was initiated at 8.4u2009mm BL and completed at 13u2009mm BL. Although the eggs of T. albonubes resembled those of other small danionin species, including Aphyocypris chinensis, Chela dadiburjori, Danio rerio, Devario malabaricus, Gobiocypris rarus, Hemigrammocypris rasborella, and Horadandia atukorali, they differed from those of A. chinensis, C. dadiburjori, G. rarus, and Horadandia atukorali in having a wider perivitelline space. The larvae and juveniles of T. albonubes were similar to those of the aforementioned seven species plus Danio albolineatus, Danio kerri, and Devario sp. (cf. D. aequipinnatus) in general morphology. However, the early life stage morphology of T. albonubes differed from them in having a dark vertical streak posterior to the otic capsule and melanophores above the eyes in the yolk sac larval stage, and a dark lateral streak with an unpigmented area just above the former on the body, a dark blotch on the caudal fin, and reddish dorsal, anal, and caudal fins during the postflexion larval and juvenile stages.

A new worm eel Neenchelys mccoskeri (Anguilliformes: Ophichthidae) from Taiwan and Japan

The myrophine ophichthid eel Neenchelys mccoskeri sp. nov. is described from the holotype and 47 paratypes, 266–522xa0mm in total length (TL), collected from Taiwan and Japan. The species is characterized by having a small head (6.4–7.7xa0% TL), a slender body (body depth at gill opening 1.5–3.2xa0% TL), its dorsal-fin origin located at mid trunk, and a mean vertebral formulaxa0of 36.9-65.0-178.7. Neenchelys mccoskeri is similar to Neenchelys daedalus McCosker 1982, but is clearly distinguished from the latter by its shorter tail length (57–63xa0% TL vs. 73–74xa0%), the location of its dorsal-fin origin (distance from dorsal-fin origin to a vertical through the anus 46–59xa0% of trunk length vs. 60–68xa0%; predorsal length 21–26xa0% TL vs. 15xa0%), shorter pectoral fins (1.5–4.3xa0% of head length vs. 22–23xa0%), and fewer total vertebrae (172–184 vs. 225–235).

Developmental morphology of the cyprinid fish Chela dadiburjori

Embryonic, larval, and juvenile development of an Indian cyprinid fish, Chela dadiburjori, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.9u2009mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk and no oil globule. Hatching occurred 50–61u2009h after fertilization at ca. 27°C. The newly hatched larvae, measuring 2.4–2.6u2009mm in body length (BL), had melanophores on the body with 14–16u2009+u200914–17u2009=u200929–31 myomeres. Two dark transverse bands on the ventral body surface and one melanophore on the lower margin of the eye in newly hatched larvae were diagnostic. Additionally, a cement organ for adhering to objects was present on the forehead of yolk sac larvae <3.1u2009mm BL. The yolk was completely absorbed at 3.5u2009mm BL. Notochord flexion was initiated at 5.0u2009mm BL and finished at 6.0u2009mm BL. Aggregate numbers of all fin rays were completed at 9.2u2009mm BL. Squamation was initiated on the caudal peduncle at 8.0u2009mm BL and completed at 10u2009mm BL. The eggs of C. dadiburjori resembled those of the closely related species Devario malabaricus and Danio rerio. The larvae and juveniles of C. dadiburjori were also similar to those of the latter species in general morphology, especially the presence of body melanophores in newly hatched individuals and a distinctive lateral streak on the head during the period from yolk sac to postflexion larvae. However, early yolk sac larvae of C. dadiburjori were more similar to those of Devario malabaricus than Danio rerio in having a cement organ on the forehead. Larvae and juveniles of C. dadiburjori differed from those of the latter two species in pigmentation on the ventral body surface at hatching and around the mouth during the period from preflexion to early postflexion larvae and in having a dark lateral streak or band on the body in postflexion larvae and juveniles.