Fecundity and size of embryonic eggs in the hermit crab Sympagurus dimorphus (Stûder, 1883) (Anomura, Parapaguridae).

MARCELO A. SCELZO; LAURA SCHEJTER; MANTELATTO F.L.

Congreso; VI Congresso Brasileiro sobre Crustáceos; 2010

Sympagurus dimorphus inhabit the southern Hemisphere from 60 to 2000 meters deep. Specimens were obtained between 100-150 m depth in the Argentinean marine waters. The study analyzed gonopores diameter, fecundity (number of eggs), and changes in size and egg volume considering twenty ovigerous females ranging 7.50–11.70 mm scutum length (SL). Gonopores are ovoid (0.74±0.11 by 0.61±0.11 mm) (F=11.791; >0.001). Direct relationship between size of gonopores and SL was found. Embryonic eggs are ovoid and larger –almost twice- than the gonopores. The larger diameters of eggs (stage I: 1.25±0.12 mm, II: 1.29±0.11 and III: 1.66±0.15) were statistically significant between stages of development (<0.0001). There was significant change in egg volume during the incubation period between stages of development (<0.0001).The mean egg volume in stage I was 0.97±0.22 mm3 (0.59-1.33 mm3), n=60, 1.34±0.36 mm3 (1.33-3.14 mm3), n=30 and 2.07±0.45 mm3 (1.33-3.14 mm3), n=40 for stage III. Egg volume was statistically significant for all stages analyzed (<0.0001). The mean fecundity was 1620.64±366.85 eggs (1043-2246), n=11. A direct relationship between the SL and fecundity was found (FE=420.39SL–2059.7; r2= 0.84). Some ovigerous females have fertile plus a high percentage of abnormal eggs reaching up 85 % of total egg mass. The strategy adopted by the species inhabiting low temperate waters deeper than 60 m involves the production of larger eggs compared with species living inshore.   Financial support: UNMDP, PICT 2007-2200, Argentina, CNPq⁄ Prosul, Brazil