Mating behavior and sperm storage on a primitive crab (Podotremata: Dromiidae)

GARCIA BENTO MA; LÓPEZ GRECO, L.S.; FERNANDO LUIS MANTELATTO; ZARA FJ

ANATOMICAL RECORD

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2022

0003-276X

Unlike Eubrachyura, Podotremata crabs show external fertilization and store sperm in a spermathecae instead of seminal receptacles. Few works were conducted on these structures found in primitive crabs. This paper describes the mating behavior of Hypoconcha parasitica under laboratory conditions highlighting the spemathecal morphology and focusing on the seminal fluid storage and release of spermatozoa. The couples were kept in aquaria where the mating behavior was recorded and described. The spermathecae from the couples were analyzed using scanning electron microscopy, X-ray micro-CT, histology, and histochemistry. No pre or post-copulatory mate guarding was observed in H. parasitica. The sperm transfer occurred with the couple maintaining the shell on back. Mating pairs were observed, with all males and two females in intermolt, being one with softshell. The pair of spermathecae is an intersegmental structure derived from the seventh and eighth thoracic segments. It is covered exclusively by the cuticle, following the Podotremata pattern. Many muscle fiber bundles are attached to the cuticular wall on the face towards the cephalothorax cavity, especially covering the laterally and slightly dorso-anteriorly region toward the apodeme of sternite 7. The spermatheca organization indicates that the process of sperm release during fertilization occurs through muscular action exerted on the wall of the chamber. Thus, the musculature distribution in Hypoconchinae distinguishes from that described to other Podotremata such as Homolidae, which shows the musculature related to the spermathecae aperture. Like the Homolidae, the first pleopod in H. parasitica seems to take part in the spermatozoa and oocyte movement between the sternum and abdomen, which form a temporal chamber where fertilization occurs. In conclusion, the spermathecal morphology and associated structures bring new information about the mechanisms involved in the sperm storage and fertilization of primitive crabs and how the Dromiidae spermatheca perform a new pattern among the poorly studied Podotremata.