Setal development and moult staging in the crayfish Parastacoides tasmanicus (Erichson), (Decapoda Parastacidae)

Abstract

Setal development through the moult cycle has been observed in the uropods and telson of the freshwater crayfish Parastacoides tasmanicus. The changes in the morphology of the setae through the moult cycle can be used as a moult stage index for this decapod. The initial formation of the setae (stage D1) for this crayfish differs from that hitherto described for other macrurans.

Determination of moult stage in the South African West Coast rock lobster Jasus lalandii (h. Milne Edwards) (Crustacea: Decapoda)

“…Van Herp and Bellon-Humbert (1978) described the setae in Astacus leptodactylus as being filled with a fibrillar protoplasm during moult Stage A, and then by a homogenous protoplasm in Stage B. Mills and Lake (1975) attributed these changes in the setal lumen of Parastacoides tasmanicus to the development of an internal matrix in the setae.…”

“…), the absence of a blackened abdominal flesh colour in 1. lalandii does not necessarily indicate that an individual is not in premoult. The premoult condition in J. lalandii has been divided into Stages Do, D l , D 2 and D3' The onset of premoult (Stage Do) in decapods is generally identified by the retraction of the epidermis from the exoskeleton (Kurup 1964, Aiken 1973, Mills and Lake 1975, Turnbull 1989), a condition known as apolysis (Jenkin and Hinton 1966). There appears to be considerable epidermal retraction in J. lalandii before the appearance of the new setae, indicating that the duration of this stage is relatively long.…”

Pleopod cuticular morphology as an index of moult stage in the ornate Rock Lobster, Panulirus ornatus (Fabricius 1789)

“…New setae formation in other decapod species occurs as early as substages Do and Dt (Stevenson et al . 1968 ;Mills and Lake 1975 ;Van Herp and BellonHumbert 1978 ;Smith and Dall 1985) . No substage between Dt and D I " could be easily distinguished in P. ornatus, as there was a rapid transition from the first appearance of setae as wispy structures to a stage that fits the DI" description.…”

“…However, pigmentation hides most of the detail, so changes in the invaginations cannot be used as a criterion for subdividing the D stage, as has been done for other species (Stevenson et al . 1968 ;Mills and Lake 1975 ;Van Herp and Bellon-Humbert 1978 ;Smith and Dall 1985) . No further visible changes occur in the pleopod tips until ecdysis .…”

“…This general scheme has been widely adopted and applied to a variety of crustaceans, including crayfish (Stevenson et al . 1968 ;Mills and Lake 1975 ;Peebles 1977 ;Van Herp and Bellon-Humbert 1978), lobsters (Aiken 1973 ;Dall and Barclay 1977 ;Lyle and MacDonald 1983) and prawns (Smith and Dall 1985). Lyle and MacDonald (1983) reported a simple, accurate and rapid method of moultstaging lobsters in field populations of P. marginatus by examination of pleopod samples.…”