Troglocaris

Jugovic, Jure, Prevorčnik, Simona & Sket, Boris, 2010, Development of sexual characters in the cave shrimp genus Troglocaris (Crustacea: Decapoda: Atyidae) and their applicability in taxonomy, Zootaxa 2488, pp. 1-21 : 9-10

Troglocaris s. str. females

The preliminary PCA analysis run on 252 females from phylogroups 1–5 and T. (T.) bosnica (10 specimens without missing data) (Appendix A), using 11 characters (Appendix C, characters as in column A, except carapace length) revealed no grouping of specimens.

Based on the shape of the pleopod I endopodite, three female groups may be distinguished:

(1) Smaller (and younger) females have a short egg-shaped pleopod I endopodite, which narrows gradually towards its end ( Figure 5 a).

(2) Non-ovigerous females: endopodite becoming longer, its distal part remarkably elongated and distinctly narrower than the proximal part. Based on its location, the distal endopodite extension may possibly represent appendix interna, although without any retinacular hooks, which may be present in adult males. Distal part of endopodite may curve and setae on the endopodite elongate ( Figure 5 b). Not all females, however, have a curved distal endopodite extension ( Figure 5 c). The only undisputed difference in the pleopod I endopodite is between the short egg-shaped endopodite (in juvenile females) and the elongated endopodite (in older, but not necessarily fully mature females). Relative endopodite length (versus exopodite length) increases in proportion to carapace length; endopodite is shorter in juvenile females and longer in adults (compare Figures 5 a and b).

(3) Ovigerous females: number and length of setae greatly increase on all parts of the pleopod ( Figure 5 c). Although the ratio of endo- and exopodite lengths in ovigerous females is highly variable, it is mostly higher than in non-ovigerous adult females ( Figure 5 b). The elongation of setae (soies ovigeres) especially on pleopods I–III, changes in shape of the pleon and epimeres (from first to fourth) and elongation of setae on the second article of pereopods III–V have already been described by Juberthie-Jupeau (1974).

We tried to find morphometric differences among the three female groups defined above using ANOVA. Of all 12 characters (carapace length and 11 ratios; Appendix C, under A), only carapace length and relative pleopod I endopodite length (pl1enex) are significantly different at p <0.001. The increase in carapace length and elongation of the endopodite, however, are both gradual with high variability within each group. Hence, no clear separation of the three female groups according to both mentioned characters could be done. Moreover, carapace length turned out to be highly sexually dimorphic, being longer in females than in males (see Appendix A).

The ontogenetic changes found in females are:

- increase in the carapace length during maturation; - elongation of pleopod I appendix interna on the endopodite; - transitional elongation of setae during 'gravidity'.

Figures

FIGURE 5. Endopodite of first pleopod in (a) juvenile (carapace length: 5.1 mm), (b) adult non-ovigerous (carapace length: 7.4 mm) and (c) ovigerous females (carapace length: 7.3 mm) in Troglocaris s. str. In ovigerous females, number and length of setae on protopodite, as well as on endo- and exopodite, are highly increased. Ai: to infer from its position, the distal extension should be appendix interna, which could be only elongated (c) or curved (b).