THE SYSTEMATIC POSITION OF HELOECIUS CORDIFORMIS (H. MILNE EDWARDS, 1837) (, ) AS REVEALED BY LARVAL MORPHOLOGY

BY

D. R. FIELDER and J. G. GREENWOOD Department of Zoology, the University of Queensland, St. Lucia, Queensland 4067,

. INTRODUCTION

Türkay (1983), following a recent study of Heloecius cordifo rm is , suggested that Heloecius is the most primitive genus within the classical Ocypodidae because males of H. cordiformis possess coxo-sternal genital openings. Conse- quently he excluded Heloecius from the sub-family Ocypodinae and proposed a new sub-family, Heloecinael), for it. Rice (1975) found that ocypodid sub- families based on adult characters were strongly reflected in larval groupings based on their mouthpart setation, telson and carapace spination. Subsequent- ly (Rice, 1980), and using an expanded series of larval characters, he listed the major families (or sub-families where they were sufficiently known) according to their general level of advancement. Heloecius was not mentioned in either of Rice's (1975, 1980) papers because no larvae from that genus were known. The purpose of this paper is to describe the first zoeal stage of H. cordiformis reared in the laboratory, and the contribution its larval characters provide in support of Turkay's (1983) proposed sub-family.

MATERIALS AND METHODS

Ovigerous females were collected from the River (27°23'S 153°9 ' E) and held individually in plastic containers (160 mm square x 200 mm deep) covered with 50 mm of diluted seawater (salinity 20%o) until their eggs hatched. All other methods were similar to those used by the authors previously, e.g., Greenwood & Fielder (1979).

RESULTS AND DISCUSSION - Description of first' zoeallarva (fig. IA-I). Dimensions (mean of 10 in- dividual measurements in mm t S.D.) are as follows: Spine to spine tip,

') Subsequently, Turkay (p.c.) has agreed that the correct spelling should be Heloeciinae, and that the suggestion that Heloeciusshould be included in a distinct sub-family was preempted by H. Milne-Edwards (1852) who proposed the name Heloeciacaea. 245

Fig. 1. Heloeciuscordiformis (H. Milne Edwards), Zoea I. A, lateral view; B, posterior view; C, first antenna; D, second antenna; E, first maxilla; F, second maxilla; G, first maxilliped; H, _ . second maxilliped; I, telson.

. 1.19 t 0.06, range, 1.08-1.26; carapace, 0.45 * 0.02 , range, 0.42-0.48; dorsal spine, 0.56 * 0.06, range, 0.42-0.62; rostrum, 0.36 t 0.04, range, 0.24-0.40; lateral spine, 0.32 * 0.01, range, 0.31-0.33; antenna, 0.22 f 0.02, range, 0.20-0.24. The dorsal spine is c. 1.2 and 1.6 times the length of the carapace and rostrum respectively. The rostrum is c. 0.8 times the carapace length.