A new species of Polyophthalmus (Annelida, Opheliidae) from the Arabian Gulf, with an insight on internal anatomy and diversity of the genus

Polyophthalmus zhadanae sp. nov. (Annelida, Opheliidae), is described from the coast of Kuwait and Saudi Arabia (Arabian Gulf) after specimens collected in the intertidal and shallow subtidal. This new species is characterised by the body pigmentation pattern, distribution of lateral eyes, presence of small dorsal and ventral parapodial cirri and pygidial features. External and internal anatomy was described after examination with SEM and micro-CT. The presence of several body structures in the genus such as a cephalic palpode-like papilla is discussed. Furthermore, the diversity of genus Polyophthalmus and the presence of Polyophthalmus pictus (Dujardin, 1839) in the Indo-Pacific is reviewed and a key to species is provided.

Early development of the Peruvian rock seabass Paralabrax humeralis (Teleostei: Serranidae): morphological description of the embryonic and yolk-sac larval stages

Describe the embryonic development of Paralabrax humeralis (Peruvian rock seabass) and the present morphology of its eggs and yolk-sac larvae using the eggs spawned by P. humeralis broodstock in captivity. The spawning occurred naturally and spontaneously in early November 2018. The egg is pelagic and round, with a diameter of 0.98 ± 0.02 mm, an oil globule, and a diameter of 0.2 ± 0.02 mm. Embryonic development started with meroblastic cleavage, reaching the first cleavage stage at 0.4 h post-fertilization (HPF), and reached 64 cells at 2.2 HPF. Blastula period, 128 cells to 30% epiboly, end at 11.3 HPF. Gastrula period, 50% epiboly to 90% epiboly, end at 19.6 HPF. In the organogenesis period, forming Kupffer’s vesicle appeared at 22.5 HPF, the separation of the caudal fin from the yolk at 30.3 HPF, and the hatching of the first larvae at 47.9 HPF. Water temperature was kept at 17.2 ± 0.2°C. The yolk-sac larvae measured 2.22 ± 0.1 mm with a pigmentation pattern of pinpoint melanophores, all along with the embryo and xanthophores in the cephalic region, trunk, and caudal region, as well as in the oil globule. The larva takes feeds from three days post-hatch-out.

Larval development of Microgobius tabogensis Meek & Hildebrand, 1928 (Pisces: Gobiidae) from a coastal lagoon in the Gulf of California, México

In fish, the larval stage constitutes the most vulnerable phase in the life cycle and reveals important ecological and evolutive information of fish and fundamental data to manage marine ecosystems. However, their identity is one of the biggest gaps in knowledge, particularly for the Microgobius genus, where only three of 15 species have been described. In this study, the larval development of Microgobius tabogensis was described based on 116 specimens (2.75-14.20 mm standard length) from Ensenada de La Paz, Mexico. The typical gobiid body shape characterized larvae, a well-developed dorsally pigmented gas bladder, a curve at the hindgut, and 27 myomeres. The pigmentation pattern in M. tabogensis consisted of a series of melanophores along the ventral postanal midline, increasing from three to seven during the preflexion stage and up to 16 in the postflexion stage. It had three to five melanophores on the ventral preanal midline, one at the jaw angle and one on the dorsal postanal midline. Through all stages, one of the ventral melanophores was normally stellate, bigger than the others, and extended between the myomeres. A dorsal melanophore was located near the end of the intestine in the preflexion stage but disappeared with growth. Notochord flexion started at approximately 4.3 mm and ended at 5.1 mm. Anal fin development started at the beginning of the flexion stage, followed by the dorsal fin. All elements of the fins were formed by the late postflexion stage (14.2 mm).

The Pupal Pigmentation Pattern and Pupal Development in the Species of Aphytis Howard (Hymenoptera: Aphelinidae)

Species identification of Aphytis on the basis of adult morphology is extremely difficult, especially in the A. lingnanensis group, with several cryptic species. Pupal pigmentation could be used as one of the taxonomic characters for Aphytis species, and in some instances, pupal pigmentation actually provided the first clue to the distinctness of cryptic Aphytis species. The present study investigated the full-grown larvae or younger pupae of Aphytis species, and pupal pigmentation and pupal development were observed and photographed. Four characteristic pigmentation patterns of Aphytis pupae were summarized including: entirely yellow, partly dark brown, entirely or predominantly black, and partly black. The species in the chilensis and mytilaspidis groups, and some unassigned species, generally have entirely, or predominantly and or partly black pupae. The species in the chrysomphali, funicularis, and proclia groups generally have the pupae entirely yellow. The species of the lingnanensis group have the pupae both entirely yellow, e.g., A. fisheri, and partly dark brown pupae, e.g., A. lingnanensis, A. holoxanthus and A. melinus. The pupae of Aphytis species in this study had a developmental duration of about 5–8 days at 27 ± 1 °C, 70 ± 5% RH and a photoperiod of 10L: 14D. It was found that the pupal skin was always melanized at the beginning stage, generally in the first day, among the pigmented pupae of Aphytis species. As development continued, the pigmentation became darker and the eye colour changed from pale red/brown to green. No significant intra-specific variation in pupal colour pattern was detected despite relatively high numbers of specimens examined, many from multiple, and different, origins. Overall, our study indicates that pupal pigmentation could be more helpful in species identification of Aphytis.

The color pattern inducing gene wingless is expressed in specific cell types of campaniform sensilla of a polka-dotted fruit fly, Drosophila guttifera

A polka-dotted fruit fly, Drosophila guttifera, has a unique pigmentation pattern on its wings and is used as a model for evo-devo studies exploring the mechanism of evolutionary gain of novel traits. In this species, a morphogen-encoding gene, wingless, is expressed in species-specific positions and induces a unique pigmentation pattern. To produce some of the pigmentation spots on wing veins, wingless is thought to be expressed in developing campaniform sensilla cells, but it was unknown which of the four cell types there express(es) wingless. Here we show that two of the cell types, dome cells and socket cells, express wingless, as indicated by in situ hybridization together with immunohistochemistry. This is a unique case in which non-neuronal SOP (sensory organ precursor) progeny cells produce Wingless as an inducer of pigmentation pattern formation. Our finding opens a path to clarifying the mechanism of evolutionary gain of a unique wingless expression pattern by analyzing gene regulation in dome cells and socket cells.

Shifts in the developmental rate of spadefoot toad larvae cause decreased complexity of post-metamorphic pigmentation patterns

Amphibian larvae are plastic organisms that can adjust their growth and developmental rates to local environmental conditions. The consequences of such developmental alterations have been studied in detail, both at the phenotypic and physiological levels. While largely unknown, it is of great importance to assess how developmental alterations affect the pigmentation pattern of the resulting metamorphs, because pigmentation is relevant for communication, mate choice, and camouflage and hence influences the overall fitness of the toads. Here we quantify the variation in several aspects of the pigmentation pattern of juvenile spadefoot toads experimentally induced to accelerate their larval development in response to decreased water level. It is known that induced developmental acceleration comes at the cost of reduced size at metamorphosis, higher metabolic rate, and increased oxidative stress. In this study, we show that spadefoot toads undergoing developmental acceleration metamorphosed with a less complex, more homogeneous, darker dorsal pattern consisting of continuous blotches, compared to the more contrasted pattern with segregated blotches and higher fractal dimension in normally developing individuals, and at a smaller size. We also observed a marked effect of population of origin in the complexity of the pigmentation pattern. Complexity of the post-metamorphic dorsal pigmentation could therefore be linked to pre-metamorphic larval growth and development.

One less monotypic genus in Leptophlebiidae (Ephemeroptera): A new species of Bessierus Thomas & Orth and new record from Brazil

A new species of Bessierus Thomas & Orth, formerly a monotypic genus, is described from Amapá State, Brazil. The type species of the genus, B. doloris Thomas & Orth, had only its nymphs described until recently, when its male imago was associated to nymphs mainly based on pigmentation pattern. Bessierus riobranco sp. n. here described has no significant difference on pigmentation pattern from B. doloris, thus the new species could be the male imago of B. doloris, and the putative imago of B. doloris a new species, or even both described imagoes could be new species. Still, a new male imago existence cannot be neglected and we opted to provide a properly description, diagnosis and illustration, hence contributing to the knowledge of mayfly neotropical diversity and future research on the genus. The generic concept of Bessierus and its type species diagnoses are altered to accommodate the new species, and a new record of B. doloris is provided.

Differences in eggshell pigmentation pattern between Common Moorhen Gallinula chloropus and Eurasian Coot Fulica atra eggs

Facultative avian brood parasites increase their reproductive output by laying eggs in the nests of conspecifics or closely related species. The Common Moorhen Gallinula chloropus is a well-known facultative brood parasite that nests in wetlands, which are utilised also by a wide range of waterfowl, including the Eurasian Coot Fulica atra. The two species breed in similar habitats and have a similar egg pigmentation pattern; thus, the Coot can be a suitable host of brood-parasitic Moorhen. To study whether there is any discernible difference between the spotting pattern of Coot and Moorhen eggs, we compared the density of different sized spots on eggs of the two species. Our results show that Coot eggs have a significantly higher density of small speckles then Moorhen eggs, while the latter species has eggs with more conspicuous larger spots. Therefore, Coots can possibly rely on these differences in eggshell pattern to recognize and eject the brood parasitic Moorhen eggs.