TY - JOUR

T1 - Anatomy of virgin and mature externae of Loxothylacus texanus, parasitic on the dark blue crab Callinectes rathbunae (Crustacea

T2 - Cirripedia: Rhizocephala: Sacculinidae)

AU - Alvarez, Fernando

AU - Bortolini, José Luis

AU - Høeg, Jens Thorvald

N1 - Keywords Parasitic crustaceans • Rhizocephala • Sacculinidae • dwarf males • externa • reproductive biology

PY - 2010

Y1 - 2010

N2 - Rhizocephalan parasites are dioecious organisms, in that one or several dwarf males are implanted into the external part of the female parasite soon after it emerges from the interior of the host animal. The structure of the female externa and its resident males is crucial for understanding both the reproductive biology and the taxonomy of these specialized parasites. We use scanning electron microscopy and histological methods to study the anatomy of juvenile and the mature externae of the rhizocephalan barnacle Loxothylacus texanus parasitizing the blue crab Callinectes rathbunae. We put emphasis on the implantation of males and the histology of the female reproductive organs. In the virgin externae, male cyprids attach around a cuticular hood covering the mantle aperture, which is partially blocked by a plug of cuticle so only trichogon larvae, not cyprids, can access the mantle cavity. This resembles the situation known from Sacculina carcini. The mature externa is characterized by a visceral mass that contains the ovary, paired colleteric glands, a single male receptacle, but paired receptacle ducts. The proximal attachment of the visceral mass is located at some distance from the basal stalk, as is characteristic for the genus Loxothylacus. The internal anatomy of the mature externa of L. texanus is in most features similar to that seen in other species of the Sacculinidae, which comprises the majority of rhizocephalan species. However, the single receptacle creates a situation where the two implanted males cannot be kept separate as in most other rhizocephalans, but pass through spermatogenesis in a common chamber. This may have unknown effects on the reproductive biology such as male-male competition.

AB - Rhizocephalan parasites are dioecious organisms, in that one or several dwarf males are implanted into the external part of the female parasite soon after it emerges from the interior of the host animal. The structure of the female externa and its resident males is crucial for understanding both the reproductive biology and the taxonomy of these specialized parasites. We use scanning electron microscopy and histological methods to study the anatomy of juvenile and the mature externae of the rhizocephalan barnacle Loxothylacus texanus parasitizing the blue crab Callinectes rathbunae. We put emphasis on the implantation of males and the histology of the female reproductive organs. In the virgin externae, male cyprids attach around a cuticular hood covering the mantle aperture, which is partially blocked by a plug of cuticle so only trichogon larvae, not cyprids, can access the mantle cavity. This resembles the situation known from Sacculina carcini. The mature externa is characterized by a visceral mass that contains the ovary, paired colleteric glands, a single male receptacle, but paired receptacle ducts. The proximal attachment of the visceral mass is located at some distance from the basal stalk, as is characteristic for the genus Loxothylacus. The internal anatomy of the mature externa of L. texanus is in most features similar to that seen in other species of the Sacculinidae, which comprises the majority of rhizocephalan species. However, the single receptacle creates a situation where the two implanted males cannot be kept separate as in most other rhizocephalans, but pass through spermatogenesis in a common chamber. This may have unknown effects on the reproductive biology such as male-male competition.

KW - Adaptation, Physiological

KW - Animals

KW - Body Patterning

KW - Brachyura

KW - Female

KW - Fertilization

KW - Genitalia, Female

KW - Genitalia, Male

KW - Host-Parasite Interactions

KW - Larva

KW - Male

KW - Microscopy, Electron, Scanning

KW - Parasites

KW - Sex Characteristics

KW - Thoracica

U2 - 10.1002/jmor.10790

DO - 10.1002/jmor.10790

M3 - Journal article

C2 - 19714752

VL - 271

SP - 190

EP - 199

JO - Journal of Morphology

JF - Journal of Morphology

SN - 0362-2525

IS - 2

ER -