Patsy A. McLaughlin

HERMIT CRAB PHYLOGENY: A REAPPRAISAL AND ITS “FALL-OUT”

Abstract The hypothesis of monophyly in Paguroidea and the relationship of this superfamily to the other three superfamilies of Anomura have been reassessed using current cladistic methods and computer generated analysis. In the analysis, 79 external morphological characters were examined for an in-group consisting of the seven paguroid families, Pylochelidae, Coenobitidae, Diogenidae, Pylojacquesidae, Paguridae, Parapaguridae, and Lithodidae (divided into the subfamilies Lithodinae and Hapalogastrinae), three hippoid families, Blepharipodidae, Albuneidae, and Hippidae, five galatheoid families, Galatheidae, Chirostylidae, Kiwaidae, Aeglidae, and Porcellanidae, and the Lomisoideas monotypic Lomisidae. The out-group was comprised of Neoglyphea inopinata, representing Fractosternalia, and the families Dromiidae and Dynomenidae representing Brachyura. This analysis has shown that Anomura indeed is a monophyletic infraorder, as is Hippoidea a monophyletic superfamily. However, while six of the paguroid families form a cohesive clade, the two subfamilies of Lithodidae form a distinct clade more closely related to the superfamily Hippoidea than to the other paguroids. Galatheoidea, as presently constituted, is polyphyletic. Aeglidae, like Lithodidae, is more closely related to Hippoidea than to the galatheoid clade formed by the families Galatheidae, Chirostylidae, and Porcellanidae. Kiwaidae is also distinct from Galatheoidea sensu stricto, but its relationship, and that of Lomisoidea, to the remainder of the anomuran taxa are unresolved in the present analysis. As a result of this reappraisal, we propose that Lithodidae be removed from Paguroidea sensu lato and elevated to superfamily rank with families Lithodidae and Hapalogastridae. Similarly, we propose that Galatheoidea be restricted to the families Galatheidae, Chirostylidae, and Porcellanidae, whereas Kiwaidae and Aeglidae are each to be elevated to superfamily rank. Anomura will then consist of seven superfamilies, Hippoidea, Lithodoidea, Aegloidea, Lomisoidea, Kiwaoidea, Galatheoidea sensu stricto, and Paguroidea sensu stricto.

Larval and early juvenile development in Paralomis granulosa (Jacquinot) (Decapoda: Anomura: Paguroidea: Lithodidae), with emphasis on abdominal changes in megalopal and crab stages

Morphological variations in the two zoeal stages and megalopa of a lecithotrophic population of Paralomis granulosa (Jacquinot) reared under laboratory conditions are reviewed. Attention is also directed to certain aspects of their development not previously considered. More importantly, the first three juvenile stages are described and illustrated for the first time. Specific consideration is given to the structural changes in the abdominal tergites during the transformation from megalopa to third crab, and ancillary information on abdominal plate development in juvenile stages four and five is provided. Total pleopod loss in both sexes and subsequent reappearance in females is discussed.

Megalopal and early juvenile development in Lithodes santolla (Molina, 1782) (Decapoda: Anomura: Paguroidea: Lithodidae), with notes on zoeal variations

Summary The megalopal and first three juvenile stages of Lithodes santolla (Molina, 1782) are described in detail and illustrated, and ancillary information on carapacial spines and abdominal plate development in juvenile stages four and five are provided. Particular emphasis has been placed on the morphological changes occurring in the abdominal tergites and to the reduction and loss of uropods andpleopods. Additionally, variations in zoeal morphology from that described in an earlier study are noted. Simplification of the mandible, retarded development in the maxillule, and setal reduction on the maxilla during the three zoeal stages may be a function of the lecithotrophy of these larvae.

A NEW FAMILY FOR A NEW GENUS AND NEW SPECIES OF HERMIT CRAB OF THE SUPERFAMILY PAGUROIDEA (DECAPODA: ANOMURA) AND ITS PHYLOGENETIC IMPLICATIONS

Abstract A new family, Pylojacquesidae, is proposed for Pylojacquesia colemani, new genus and species. Although the new family, with its monotypic genus, exhibits characters of both superfamilies of the Section Paguridea, it is tentatively assigned to the Paguroidea until additional material becomes available that would permit a more detailed study. The new family Pylojacquesidae is diagnosed, and its type genus and species are described and illustrated. The possible phylogenetic relationships of the new genus are discussed. A key to all the families of hermit crabs is presented.

Studies on the provenzanoi and other pagurid groups: VI. Larval and early juvenile stages of Pagurus ochotensis Brandt (Decapoda; Anomura; Paguridae) from a northeastern Pacific population, reared under laboratory conditions

Zoeal, megalopal, and early juvenile stages of Pagurus ochotensis (Brandt, 1851) from a northeastern Pacific population are described from laboratory-reared individuals. Zoeal and megalopal development in this population is compared with that described for a population of this species from Hokkaido, Japan. First and second juvenile crab stages of this species are described for the first time. The nearly identical developmental morphology of the two populations supports the earlier synonymy of the northeastern Pacific species, Pagurus alaskensis (Benedict) with P. ochotensis.

Aspects of evolution in the anomuran superfamily Paguroidea: one larval prospective

Summary McLaughlin and Lemaitre (1997), in their examination of carcinization in the Anomura, rejected the traditional concept of paguroid evolution, which had consistently maintained that the lithodid crab-like body form evolved from a typical shell-dwelling hermit crab. Their hypothesis proposed just the reverse, i.e., the lithodid crab-like body form gave rise to the simple hermit crab body form through calcium loss, habitat change and consequential morphological adaptations. Their original hypothesis was based on characters derived from adult morphology, but they suggested that larval data would support their view. The megalopal and first or first- and second-crab stages of representatives of both subfamilies of the Lithodidae provide the first of such larval information. Ten species in eight genera have been examined specifically for development of abdominal tergites. These data, although preliminary in scope, unequivocally disprove the Bouvierian concept of lithodid abdominal plate development, and in so doing, lend substantial support to McLaughlin and Lemaitres hypothesis.

Descriptions of megalopa and juveniles of Sympagurus dimorphus (Studer, 1883), with an account of the Parapaguridae (Crustacea: Anomura: Paguroidea) from Antarctic and Subantarctic waters

Four species and a megalopa of the hermit crab family Parapaguridae were obtained during cruises of the USNS Eltanin (1962–8) and Hero (1971) to Antarctic and Subantarctic waters. Adults, numerous juveniles, and the presumed megalopal larvae of Sympagurus dimorphus (Studer, 1883), are reported. Morphological variations and pleopod development in juveniles, and the megalopa of this species, are described and illustrated. Sympagurus haigae (De Saint Laurent, 1972), and Parapagurus latimanus Henderson, 1888, previously were either poorly defined or known from only a few localities; they are diagnosed or their descriptions amended, and illustrated. Parapagurus bouvieri Stebbing, 1910, was found off the coast of New Zealand, extending its range across the Indian Ocean. It is postulated that, at least in some species of Sympagurus, megalopal development is more variable than previously assumed.

Larval and Early Juvenile Development in Pagurus Stevensae Hart, 1971 (Decapoda: Anomura: Paguridae), Reared in the Laboratory

ABSTRACT The zoeal, megalopal, and first three juvenile stages of Pagurus stevensae Hart, 1971, are described and illustrated from larvae reared under laboratory conditions. Zoeae of P. stevensae are easily distinguished from the larvae of other local hermit crab species by several distinctive morphological characters. The most readily observed are the fourth telsonal process, which is elongate and fused to the telson in all stages, and the antennal scaphocerite, which is armed, not only with a prominent distal spine, but with 3 spinose processes adjacent to its base. Additionally, the antennal endopod terminates in a strong bifid spine, at least in the first 2 stages. Certain aspects of development in this species suggest that hypotheses regarding character polarities within the Paguridea be reassessed.

Larval and early juvenile development in the Lithodidae (Decapoda: Anomura: Paguroidea) reared under laboratory conditions: 1. Subfamily Lithodinae: Lopholithodes mandtii Brandt, 1848

Summary Four regular zoeal, the megalopal and first two crab stages of Lopholithodes mandtii Brandt were reared under laboratory conditions. Additionally one specimen passed through a fifth zoeal stage. All stages are described and illustrated.

Larval and early juvenile development in the Lithodidae (Decapoda: Anomura: Paguroidea) reared under laboratory conditions

Summary Four zoeal, the megalopal and the first crab stage are described and illustrated for Placetron wosnessenskii Schalfeew (Hapalogastrinae). Morphological differences found in some of the developmental sequences between members of the two subfamilies of the Lithodidae are reviewed.