A new flatworm species of Temnocephala (Rhabdocoela, Temnocephalidae) ectosymbiont on the freshwater crab Valdivia serrata (Decapoda, Trichodactylidae) from Amazonas, Colombia

Abstract

A new species of temnocephalan is described from the branchial chambers of Valdivia serrata in Colombia as Temnocephala ivandarioi sp. nov. The most distinctive characters of the new species are in the cirrus and the epidermal 'excretory' syncytial plates. In the present study, the terminology to describe the cirrus of species of Temnocephala is updated. Comparison between the shape of the cirrus of the temnocephalans associated with trichodactylid crabs is also provided.

Keywords: Crustacea; Reserva Natural Tanimboca; Temnocephala ivandarioi sp. nov.; taxonomy.

Figure 1.

Temnocephala ivandarioi sp. nov. and Valdivia serrataA paratype of Temnocephala ivandarioi sp. nov. showing an egg, ventral view B adult paratype stained in Meyer´s paracarmine C holotype stained in Borax carmine D male specimen of V. serrataE abdomen F gonopods, lateral view. Scale bars: 200 µm (A–C); 10 mm (D–F).

Figure 2.

Temnocephala ivandarioi sp. nov. A adult specimen diagram, showing adhesive disk (ad), anterior testes (at), cyanophilous glands (cg), disk glands (dg), excretory vesicle (ev), Haswell´s glands (hg), intestinal sac (i), mouth (m), pharynx (ph), posterior testes (pt), rhabditogenic glands (rg), tentacles (t), and vitellarium (v) B reproductive system, showing female reproductive complex: anterior portion of the distal vaginal sphincter (advs), anterior portion of the proximal vaginal sphincter (apvs), genital atrium (ga), genital pore (gp), posterior portion of the distal vaginal sphincter (pdvs), posterior portion of the proximal vaginal sphincter (ppvs), ovary (ov), vagina (va), and resorbens vesicle (vr); and male reproductive organs: cirrus (c), prostatic bulb (pb), prostatic vesicle (pv), seminal vesicle (sv), and vasa deferentia (vd) C line drawing of cirrus in different focusing planes, showing the sclerites portion of the introvert (sp), and proximal limit of the introvert (arrows). Scale bars: 200 µm (A); 100 µm (B); 20 μm (C).

Figure 3.

Temnocephala ivandarioi sp. nov. details of epidermal excretory syncytial plates (DLSPs) and eggs A antero-lateral area observed with SEM showing leftmost tentacle and left DLSP, arrow showing contour and position of excretory pores (n) B line drawing of entire specimen showing the DLSP_sC egg observed with SEM showing the filament (fi), peduncle (pe), and plane of fracture of the operculum (pf) D line drawing of a whole egg showing the oblique fracture plane to the longitudinal axis of the egg E live adult specimen showing red eyespot pigment F unhatched egg showing the filament (fi) G, H live eggs deposited on branchial chambers of V. serrata. Scale bars: 100 μm (A–F); 1mm (G, H).

Figure 4.

Details of the reproductive system of Temnocephala ivandarioi sp. nov. A, B partial female reproductive system, showing: anterior portion of the distal vaginal sphincter (advs), anterior portion of the proximal vaginal sphincter (apvs), distal vaginal sphincter (dvs), genital atrium (ga), posterior portion of the distal vaginal sphincter (pdvs), posterior portion of the proximal vaginal sphincter (ppvs), proximal vaginal sphincter (pvs), ovary (ov), vagina (va), and vesicula resorbens (vr) C, D partial male reproductive system, showing: cirrus (c), prostatic bulb (pb), seminal vesicle duct (svd), seminal vesicle (sv), and vasa deferentia (vd) E, F cirrus introvert observed in different focusing planes, view of the circle of sclerites (sp) in the distal portion of the introvert and the smooth portion (smp) in the proximal limit of the introvert (pli). Scale bars: 50 μm (A–D); 20 μm (E, F).

Figure 5.

Diagrams showing the terminology used to describe the cirrus of the species of Temnocephala (terminology updated from Sewell et al. (2007), Seixas et al. (2011), Garcés et al. (2013), and Ponce de León et al. (2015); diagrams modified from Sewell et al. 2007: 205, fig. 2).

Figure 6.

Diagrams of the cirrus of the species of Temnocephala associated with trichodactylid crabs. Terminology based on the cirrus structure (see comparative notes and Fig. 5). ATemnocephala ivandarioi sp. nov. (present study) BTemnocephala lanei Pereira & Cuocolo, 1941 CTemnocephala longivaginata Seixas, Amato & Amato, 2011 DTemnocephala lutzi Monticelli, 1913 (Amato et al. 2005) ETemnocephala microdactyla Monticelli, 1903 FTemnocephala pignalberiae Dioni, 1967 (Amato et al. 2010) GTemnocephala santafesina Dioni, 1967 HTemnocephala trapeziformis Amato, Amato & Seixas, 2006 ITemnocephala travassosfilhoi Pereira & Cuocolo, 1941. Key: Shaft [shape: CO–cone; FU–funnel]; [curvature: CU–curved up; ST–straight; CD–curved down]. Introvert [shape: CY–cylindrical; CO–cone; SC–scoop]; [armed with: UN–unarmed; SP–spines; SL–sclerites; RI–ridges; ND–not described]; [angle: NO–not oblique; VO–very oblique]; [curvature: NC–not curved; FC–forward curved; BC–backward curved].