Phaenocora gilberti Houben and Artois

Houben, Albrecht M., Steenkiste, Niels Van & Artois, Tom J., 2014, Revision of Phaenocora Ehrenberg, 1836 (Rhabditophora, Typhloplanidae, Phaenocorinae) with the description of two new species, Zootaxa 3889 (3), pp. 301-354 : 329-330

Phaenocora gilberti Houben and Artois sp. nov.

( Figs 1 E–H, 4)

Holotype: A horizontally-sectioned specimen, Cootes Paradise (Ontario, Canada). Waterweed-like and similar macrophytes in cove, with rich vegetation ( SMNH Type-8672), 43°16’02.5”N; 79°55’13.2”W, 17 May 2009.

Paratypes: Two sagitally-sectioned specimens (HU nos 568–569), three whole mounts (HU nos 570–572), same collection data as holotype.

Etymology: Dedicated to Dr. Chauncey McLean Gilbert, for his contribution to our knowledge of microturbellaria of N. America, the genus Phaenocora in particular.

Diagnosis: Animals about 1 mm long, with a tail. Body colour green or pinkish. The eyes have a pink appearance under reflective light and purple under transmissive light. Body pigmentation in the anterior body part, pink under reflective light and purple under transmissive light. Zoochlorellae sometimes present. Male copulatory organ of the duplex-type IIB. Proximal part of the invaginated cirrus with a pseudocuticula, the distal part of the invaginated cirrus bearing spines. Evaginated copulatory organ with a bulge, which is also visible on the distal part of the invaginated ejaculatory duct. Female genital system of the AGLOBULATA - type, with a long female genital canal, which has giant unicellular glands at its proximal part and at the junction between the female genital canal and the superior genital atrium. With a small genito-bursal duct, a lobed intestinal bursa, and a burso-intestinal duct with a valvular complex at the proximal end.

Description: Animals about 1 mm long (measured on serial sections), body colour green or pinkish. Pink eyes and pink pigmentation occur in the anterior body part. Zoochlorellae present in some specimens, absent in others ( Figs 1 E–F).

The male copulatory organ ( Fig. 1 G, 4B1, 4C) is of the duplex-type IIB. The cirrus is subdivided into three parts: a proximal part lined with pseudocuticula, a median part lined with a somewhat frayed, nucleated epithelium and a distal part lined with a thin epithelium and spines. The most proximal spines are about 3 µm and the distal spines are about 1 µm long. The evaginated copulatory organ shows a bulge that is also visible on the distal section of the invaginated cirrus ( Figs 1 G, 4C: b).

The female genital system (Figs 4B1, 4B2) resembles that of P. aglobulata sp. nov. The gut and the bursointestinal duct (Fig. 4B2: dbi) are connected to each other by a valvular apparatus. The intestinal bursa (Fig. 4B1: bi), which is heavily lobed, is further connected to the long female genital canal (Fig. 4B1: fgc) by a short genitobursal duct (Fig. 4B1: dgb). The oviduct (Fig. 4B1: od) opens at the junction of the genito-bursal duct and the female genital canal. The vitelloduct and its opening into the female genital system were not clearly observed. The female genital canal has six spherically-shaped giant unicellular glands (cf. Gilbert 1935; also Fig. 4B1: gc1). Two of them are situated at the proximal end of the female genital canal near its point of union with the genito-bursal duct (only one is drawn in the reconstruction). The shell glands (Fig. 4B1: sg) are situated dorsally and laterally around the female genital canal, and open into the distal part of this canal. At its distal end there are also four giant unicellular glands (Fig. 4B1: gc2) situated around the junction of the female genital canal and the superior genital atrium. The female genital canal receives many secretion strands, which enter through the muscular sheet (Fig. 4B3: gl4; cfr. P. aglobulata sp. nov.).

Remarks: The giant unicellular glands can only be counted on the holotype. Therefore, it is possible that the number of cells can vary among specimens.

The epithelium of the seminal vesicle does not protrude and does not form a cavity at the point where the proximal and distal bulbi connect, which is a clear difference with the situation in P. aglobulata sp. nov.

Figures

FIGURE 1. Photographs of live animals A, P. evelinae. B, P. foliacea from South Africa. C, P. foliacea from India. D, P. aglobulata sp. nov.. E – H, P. gilberti sp. nov.: E – F, pigmentation of the head. G, male copulatory organ. H, female genital canal.