Fig 1.
Habitats of the four studied species from the family Onchidiidae.
The illustration was created using Photoshop. Onchidium reevesii primarily occupies wetlands, Platevindex mortoni can survive well in both water and wetlands, and Paraoncidium reevesii and Peronia verruculata predominantly dwell in water. Note: The photograph outlined in red shows the dendritic gills in the dorsal skin of Peronia verruculata.
Table 1.
PCR primers used in gene cloning.
Fig 2.
Light microscopy of the dorsal skin of four species in the Onchidiidae family.
(A-D) An overview of the dorsal skin of (A) Onchidium reevesii (×40), (B) Paraoncidium reevesii (×40), (C) Platevindex mortoni (×40) and (D) Peronia verruculata (×40). (E-H) Dermis layer of (E) O. reevesii (×40), (F) P. reevesii (×40), (G) P. mortoni (×40) and (H) P. verruculata (×40). (I-L) Histological observation of glands in four species of Onchidiidae: (I) O. reevesii (×40), (J) P. reevesii (×40), (K) P. mortoni (×40), and (L) P. verruculata (×40). E, epidermis; D, dermis; SS, stratum spongiosum; SC, stratum compactum; CM, cuticular membrane; SCO, stratum corneum; SGR, stratum granulosum; SGE, stratum germinativum; MG, mucous gland; GG, granular gland; PC, pigment cell; MF, muscle fiber; BS, blood sinus; CP, calcium particle.
Table 2.
Dorsal skin thicknesses of four species in the family Onchidiidae (Unit: μm).
Fig 3.
SEM observations of the lung sac of four species in the family Onchidiidae.
(A-B). Paraoncidium reevesii; (C-D). Platevindex mortoni; (E-F). Peronia verruculata; (G-H). Onchidium reevesii.
Table 3.
Structural differences among the lung sacs of four species in the family Onchidiidae.
Table 4.
Sequence information of four Onchidiidae species.
Table 5.
Annotated unigenes based on gene ontology.
Fig 4.
Phylogenetic analysis of 13 species.
The names presented in non-black text highlight the main objects of this research study. The phylogenetic tree was inferred using Bayesian methods with MrBayes version 3.2.4. This tree was generated using 18S sequences.
Table 6.
Primer sequences and characterization of 26 SNPs in Onchidium reevesii.
Fig 5.
Expression levels of the NMHC II gene in different tissues from four representative Onchidiidae species.
S = Onchidium reevesii; M = Platevindex mortoni; R = Paraoncidium reevesii; V = Peronia verruculata (little expression in the tested tissues).
Fig 6.
RT-qPCR analysis of the expression profiles of MyHC in different tissues of onchidiids.