Itaipusa divae Marcus, 1949

Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, Zootaxa 4948 (4), pp. 451-500 : 456-457

Itaipusa divae Marcus, 1949

( Fig. 1A–C )

Known distribution. Bahia de Santos (Type Locality) and Pitangueiras, São Sebastião, Brazil (see Marcus 1949 for details). Three localities in Galapagos Islands and several in Curaçao (see Reygel et al. 2011 for details).

New records and material. Observations on live specimens. Three whole mounts from Siboney (19°57’34”N; 75°42’07”W), Santiago de Cuba, Cuba (February 7 & May 15, 2016; April 4, 2017) (HU XIII.2.42– XIII.2.44), intertidal up to 0.6 m deep, fine-grained sand, salinity 32–35 ‰. One whole mount from La Mula (19°56’44”N; 76°45’19”W), Guamá, Santiago de Cuba, Cuba (June 29, 2016) (HU XIII.2.45), intertidal rocky pools, on the algae Digenia simplex and Cladophoropsis macromeres , salinity 33 ‰. One whole mount from Macabí (20°54’13”N; 75°43’40”W), Banes, Holguín, Cuba (April 23, 2017) (HU XIII.2.46), fine-grained sand, 0.3 m deep, salinity 34 ‰. Three whole mounts from a beach east of the Marine Research Station of Achotines (07°24’47”N; 80°10’20”W), Vera Cruz, Panama (February 28, 2016) ( USNM 1642500–1642502), just over the rocky hill, on green algae ( Blidingia / Enteromorpha -like). One whole mount (HU XIII.2.47) and one serially-sectioned specimen (HU XIII.2.48) collected in Anse Vata Bay (22°18’19”S; 166°26’50”E), Nouméa, New Caledonia (October 22, 2003), on algae ( Ulva -like) and sediment taken from rocks in the mouth of a small river.

Remarks. Habitus and overall anatomical organisation of our specimens correspond to the description by Marcus (1949). The specimens are unpigmented, with two eyes. The specimens from Cuba are 0.8–1 mm long (x̄ = 0.9 mm; n = 5), the specimens from Panama are 0.9–1.3 mm long (x̄ = 1.1 mm; n = 2), and the specimen from New Caledonia is 1 mm long. The syncytial epidermis is 3 μm thick (in the serially-sectioned specimen from New Caledonia) and completely ciliated. Cilia 2–3 μm long. The epidermis has a thin basal lamina and is lined internally by a thick layer of circular muscles. Rhabdites present over the entire body surface, more numerous in the posterior body half, 2–3 μm long.

The proboscis has the characteristic koinocystidid construction, with a strong juncture sphincter (see Brunet 1972; Karling 1980). It is 10% of the body length in live specimens from Panama and 15% in the specimens from Cuba and New Caledonia.

The pharynx ( Fig. 1A ) is located in the anterior body half. Its diameter is 15% of the body length in live specimens from Panama and New Caledonia and 20% in specimens from Cuba. The prepharyngeal cavity ( Fig. 1A : ppc) is lined by a low, nucleated epithelium (thicker in the distal 1/3 of the lumen) and surrounded by an external layer of longitudinal muscles. Four types of glands open very close to each other in the distal part of the pharynx lumen: two types containing a coarse-grained eosinophilic secretion, one stained yellowish ( Fig. 1A : phg4) and the other stained brownish ( Fig. 1A : phg1), one containing a fine-grained eosinophilic secretion (stained pinkish) ( Fig. 1A : phg2), and one a coarse-grained basophilic secretion (stained dark blue-black) ( Fig. 1A : phg3). Coarse-grained basophilic glands (Minot’s glands; Fig. 1A : oeg) open into the oesophagus ( Fig. 1A : oe). The musculature of the pharynx consists of a layer of longitudinal muscles outside of the septum ( Fig. 1A : lm), which is continuous with that surrounding the prepharyngeal cavity, and a circular one just inside of the septum ( Fig. 1A : cm1). The distal opening of the pharynx is lined by a thick layer of longitudinal muscles, which in sagittal sections gives the impression of forming a lip-like structure ( Fig. 1A : slm). The pharynx lumen is surrounded by a low epithelium and an outer layer of circular muscles ( Fig. 1A : cm2) and an inner layer of longitudinal muscles ( Fig. 1A : ilm). Radial muscles ( Fig. 1A : rm) run between the internal and the external walls. The mouth ( Fig. 1A : m) is surrounded by a sphincter ( Fig. 1A : sph).

The oviform copulatory bulb ( Fig. 1B–C ) is 76–86 μm long (x̄ = 81 μm; n = 5) in the specimens from Cuba, 86–89 μm long (x̄ = 88 μm; n = 2) in the specimens from Panama, and 130 μm long in the specimen from New Caledonia. The spiny cirrus as a whole ( Fig. 1B–C : ci) is 35–41μm long (x̄ = 38 μm; n = 5) and 29–37 μm wide (x̄ = 33 μm; n = 2) in the specimens from Cuba, 20–36 μm long (x̄ = 29 μm; n = 3), and 28–44 μm wide (x̄ = 36 μm; n = 2) in the specimens from Panama, and 57 μm long and 36 μm wide in the specimen from New Caledonia. The cirrus is formed by transverse, sclerotised folds bearing tightly-packed spines. Spines are 2–3 μm long (x̄ = 2 μm; n = 25) in the specimens from Cuba and New Caledonia, and 3–4 μm long (x̄ = 4 μm; n = 25) in the specimens from Panama.

Figures

FIGURE 1. A–C, Itaipusa divae Marcus, 1949. A, sagittal reconstruction of the pharynx from the left hand side. B–C, copulatory bulb (specimens from Cuba and Panama, respectively). D–E, Itaipusa karlingi Mack-Fira, 1968. D, copulatory bulb. E, cirrus and penis papilla. A–B with proximal end toward top of figure, C–E with proximal end toward left of figure.