SEXUALITY AND EARLY DEVELOPMENT IN AQUATIC ORGANISMS Sex Early Dev Aquat Org Vol. 1: 45–55, 2014 doi: 10.3354/sedao00006 Published online July 1 INTRODUCTION Many penaeoid shrimp are important fishery resources in tropical and subtropical countries (FAO 2001, 2012, Salas et al. 2011). Although penaeoid catch volumes are considerably lower than those of many other shrimp species, these decapods are highly traded due to their high market value, and are mainly exported to countries with affluent economies (FAO 2001). Diminishing catches in coastal waters have motivated the fishing industry to explore off- shore and deepwater resources (Morato et al. 2006), a trend that has also been observed in Latin Ameri- can shrimp fisheries (Arana et al. 2009, Wehrtmann et al. 2012). In this region, fishing activities focus on benthic and demersal invertebrates, and almost half of these resources are threatened by overexploitation (Arana et al. 2009). One of these exploited deepwater shrimp species is the solenocerid shrimp Solenocera agassizii Faxon, 1893 (kolibri shrimp; local name ‘camarón fidel’), which is distributed along the Pacific coast © The authors 2014. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are un- restricted. Authors and original publication must be credited. Publisher: Inter-Research · www.int-res.com *Corresponding author: v.fresia@gmail.com Secondary sexual characters and spermatophores of Solenocera agassizii (Decapoda: Solenoceridae), including a comparison with other solenocerid shrimp Fresia Villalobos-Rojas 1, * , Ingo S. Wehrtmann 1,2 1 Unit for Fishery Research and Aquaculture (UNIP) of the Research Center for Marine Science and Limnology (CIMAR), University of Costa Rica, 11501-2060 San José, Costa Rica 2 School of Biology, University of Costa Rica, 11501-2060 San José, Costa Rica ABSTRACT: Solenocera agassizii is commercially exploited along the Costa Rican Pacific coast and represents around 30% of the country’s total shrimp catch. Despite its economic importance, information on its biology is scarce. Here we describe its secondary sexual characters and sper- matophores. The open thelycum is located between Sternites XIII and XIV. A pair of parallel setose projections (Sternite XIV) is distally curved in larger females (< 30 mm carapace length); a disk-shaped projection (Sternite XIII) emerges from Pereopod IV and projects towards Sternite XIV, and a triangular emargination is present (Sternite XIII). The semi-open petasma with cincin- nulli connecting the pleopods in mature males has sclerotized dorsolateral (DL), ventrolateral (VL) and ventromedian (VM) lobules. The VM tooth-like projections fit the VL tooth-like projections. The DL and VL lobules end in a leaf-like, less sclerotized projection and are separated by a gap. The VL lobule has a patch of spinules and a highly sclerotized costa. An elongated appendix mas- culina (AM) with concave margin forms a distal subtriangular lobe and has a DL margin with an aggregation of setae. The AM fits inside the appendix interna (AI) and is shorter and narrower than the AM. The spermatophore has superior (wing) and inferior (germinate body) sections. The GB ends in a triangular hook-like structure. The thelycum resembles that of S. geijskesi, whereas the petasma, AM and AI are similar to those of Atlantic solenocerids. The complex spermatophore resembles that of other penaeoid shrimp. According to evolutionary trends, S. agassizii can be considered as a less derived species within the Dendrobranchiata. KEY WORDS: Thelycum · Petasma · Appendix masculina · Appendix interna · Spermatophore OPEN PEN ACCESS CCESS