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Zoology Publications from Victoria University of Wellington—Nos. 78, 79 and 80

Family Crangonidae

Family Crangonidae

The following species have been recorded from the New Zealand region: Pontocaris lacazei (Gourret, 1888), Pontophilus australis (Thomson, 1879), P. acutirostratus Yaldwyn, 1960, P. challengeri Ortmann, 1893, P. chiltoni Kemp, 1911, P. hamiltoni Yaldwyn, 1971, P. indicus de Man, 1918, P. pilosoides Stephenson, 1927, P. quadrispinosus Yaldwyn, 1971, P. yaldwyni Zarenkov, 1968, Prionocrangon curvicaulis Yaldwyn, 1960, Sclerocrangon knoxi Yaldwyn, 1960, S. richardsoni Yaldwyn, 1960. In addition, the Family Glyphocrangonidae may be represented in deep water off New Zealand (Richardson & Yaldwyn 1958), and larvae of species belonging to this family could possibly be confused with those of the Crangonidae on the basis of characters given below.

Early larvae of Pontocaris lacazei have been described by De Simón (1979), and larvae of Pontophilus australis, P. chiltoni, P. hamiltoni and P. pilosoides by Packer (1983). No other larvae of the New Zealand Crangonidae are known. However, on the basis of their relatively large egg size and on published information for larvae from outside the New Zealand region, the species of Prionocrangon and Sclerocrangon almost certainly have abbreviated larval development. This is probably also true for the Glyphocrangonidae.

Larvae of the Glyphocrangonidae and Sclerocrangon with abbreviated development, described from beyond the New Zealand region, have more than the usual 8+8 telsonic setae (e.g. Dobkin 1965, Makarov 1968). In larvae of Sclerocrangon the posterior margin of the telson is either smoothly rounded posteriorly (Fig. 2F) or weakly indented (Sars 1890, Wollebaek 1906, Makarov 1968) whereas in Glyphocrangon spinicauda the posterior margin of the telson bears a median spine or "prominence" (Dobkin 1965) (Fig. 2G). To the author's knowledge no larvae of Prionocrangon have been described.

All known larvae of the genus Pontophilus Leach can be separated into three distinct groups (Packer 1983). The first group includes larvae referred to the genus Pontophilus. The second group includes larvae referred to Philocheras Stebbing, which was synonymized with Pontophilus Leach by Kemp (1911) - a revision followed by the majority of authors with regard to the adults (Lebour 1954, Williamson 1982) but not accepted by authors working with larval material (see Williamson page 6(1960) for synopses of larval data and keys to the larvae forming these two groups). These groups have been referred to as 'Pontophilus-group A' and 'Pontophilus-group B' respectively (Packer 1983). Larvae of Pontophilus australis, P. chiltoni, P. hamiltoni and P. pilosoides, from the New Zealand region, form the third group. However, larvae of the five species from New Zealand waters which have yet to be described could belong to any of these three groups, and so provision for this possibility is made in the key given below.

Larvae of the family Crangonidae can be distinguished by the following combination of characters.

Crangonid larval characters

1.Eyes oviform, close together (e.g. Fig. 2A).
2.Carapace with ventral margins convex, without supraorbital spines (Fig. 2D).
3.Inner flagellum of antennule in the form of a stout rod (e.g. Fig. 2A) or of many segments (Fig. 2I).
4.Antennal exopod not distally segmented (except in early larvae of Pontocaris lacazei (Fig. 2I).
5.Exopod of maxilla without proximal extension (Fig. 2C, cf. Figs. 3K, 4I).
6.Pereiopod 1 with rudimentary subchela in late larvae, propodus broad (Fig. 2D).

Key to larvae of New Zealand Crangonidae
A. Larvae with all appendages present except the uropods, or uropods present but endopod rudimentary; in latter case pleopod buds large, i.e. abbreviated development Sclerocrangon Prionocrangon Fam. Glyphocrangonidae
Larvae with unabbreviated development B
B. Abdomen less than twice length of carapace, without dorsomedial spine on somite 3 (although this somite may have paired postero-lateral spines); posterior margin of telson weakly concave or straight Cpage 7
Abdomen more than twice length of carapace, with dorsomedial spine on somite 3; posterior margin of telson strongly concave D
C. Base of rostrum with concave lateral margins (Fig. 2A); exopods of maxillipeds 2-3 and pereiopods 1-2 with no more than six setae (Fig. 2D); posterior margin of telson straight from zoea 4 onward Pontophilus australis P. chiltoni P. hamiltoni P. pilosoides (other Pontophilus spp.?)
Base of rostrum with convex lateral margins (Fig. 2B); exopods of maxillipeds 2-3 and pereiopods 1-2 with more than six setae; posterior margin of telson weakly concave in ll larvae 'Pontophilus-group B'
D. Abdominal somite 5 with strong posterolateral spines; inner flagellum of antennule horter than carapace (Fig. 2H). 'Pontophilus-group A' (? Including P. indicus & P. challengeri from group 1 of Kemp 1916)
Abdominal somite 5 without posterolateral spines; inner flagellum of antennule longer than carapace, of many segments from zoea 2 onward (Fig. 2I) Pontocaris lacazei