A new species of Trichodoridae, Trichodorus elefjohnsoni, is described from undisturbed regions of Great Smoky Mountains National Park, United States. It resembles T. orientalis De Waele &Hashim, 1984, T. persicus De Waele &Sturhan, 1987, and T. taylori De Waele, Mancini, Roca, ' Lamberti, 1982 in arrangement of ventromedian cervical papillae and posterior preanal supplements, but differs by co...

Although contemporary trends indicative of evolutionary change have been detected in the life-history traits of exploited populations, it is not known to what extent fishing influences the evolution of alternative life-history tactics in migratory species such as salmonids. Here, we build a model to predict the evolution of anadromy and residency in an exploited population of brook charr, Salve...

A short diagnosis and a more detailed diagnosis of the genus Laelaspis are presented. Until now, a total of 40 described species belong to the genus, including a new species described here, and excluding the four following species previously described as Laelaspis or Hypoaspis (Laelaspis): L. badrii Nasr & Nawar [considered as Cosmolaelaps badrii comb. nov.], L. zuluensis Trägårdh, Hypoaspis (L...

The in vitro effect of 17α, 20β-Dihydroxyprogesterone on the maturation of Persian sturgeon (Acipenser persicus) oocytes for 7, 10, 12, 24 and 30th hours of incubation were investigated. Blood serum, testosterone (T), progesterone (P4) and 17-β estradiol concentrations were measured using enzyme-linked immuno-sorbent assay (ELISA). The oocytes were incubated in SIS, RM2, L-15 and PSACF media in...

Fish skin is essential for survival, maintenance of body shape, and protection against the shock and infection. During week 1 of sturgeon larval development, the epidermis is thin and not differentiated in various layers yet, but by week 4-6 the thickness increases and various layers appear, depending upon the region of the body. Mucous cells differentiate early in development on the surface of...