Castrada multispina, Noreña, Carolina, Eitam, Avi & Blaustein, Leon, 2008

Noreña, Carolina, Eitam, Avi & Blaustein, Leon, 2008, “ Microturbellarian ” flatworms (Platyhelminthes) from freshwater pools: New species and records from Israel, Zootaxa 1705, pp. 1-20 : 15-16

Castrada multispina sp. nov.

( Figure 12 )

Locality. Temporary, artificial pool in Hai Bar Carmel Nature Reserve.

Material. Five individuals, squash preparations, live observations, sagittally sectioned individuals.

Holotype. A sagittally-sectioned specimen deposited in the Department of Zoology at Tel Aviv University, Israel, Catalogue Number: VR-25071.

Etymology. The specific name refers to the numerous spines and thorns inside the blind sac.

Description. Sexually mature animals up to 0.5 mm long, width up to 0.15 mm ( Fig. 12 A). Body shape lanceolate: front rounded, tail pointed. The body colouration is whitish to translucent white. Eyes absent. Adenal rhabdites arranged at the anterior end. Pharynx rosulatus at the end of the first third of the body.

The elongate testes are situated ventrally at the sides of the pharynx. The vasa deferentia arise from the posterior end of the testes, and enter together into the proximal region of the copulatory organ.

The atrium copulatorium, situated behind the pharynx, shows a distal constriction (no sphincter) and surrounds the copulatory organ, the bursa copulatrix and one spiny blind sac. The copulatory organ is pearshaped with a cup-like ductus ejaculatorius with double-laminar walls ( Fig. 12 B). The bursa copulatrix is formed by a protuberance of the atrium. The distal region of the bursa copulatrix is pointed and has small spines in its inner walls ( Fig. 12 B). The proximal section of the bursa widens and lacks a stalk or spines.

The inner walls of the blind sac are covered with sharp spines ( Fig. 12 B), longer (length: 1–2.3 μm) in the distal section. The shape and size of the spines at the distal region differ among individuals, depending on age and degree of sexual maturity (compare different sizes of spines in Fig. 12 B and 12C).

The receptaculum seminis is incorporated into the oviduct. The ovary has the typical shape of the genus.

Ecological features. Castrada multispina was collected during the spring (March 2002) in an artificial pool with cement walls at Hai Bar Carmel (see TABLE 1 ).

Discussion. Castrada multispina is closely related to Castrada infernalis Papi, 1951 , C. viridis Volz 1898 and C. horrida Schmidt, 1861 .

The relationship is based on the configuration of the male apparatus formed by only one spiny blind sac, a pear-shaped copulatory organ and a conical spiny bursa copulatrix. The most conspicuous differences concern the type and size of the spines within the blind sac. C. multispina shows large, sharp spines along the entire inner surface of the blind sac, while C. infernalis bears large spines only at the base; C. viridis and C. horrida lack large spines.

The absence of sphincters in the atrium copulatorium of C. multispina further differentiates this species from C. infernalis and C. viridis , but this characteristic is apparently shared with C. horrida .

Due to its morphological characteristics, C. multispina can be included in the C. viridis group, characterized by the presence of an atrium copulatorium with thorns or hooks, spiny blind sacs and bean shaped spermatophores without a stalk (group 3 of Luther, 1963).

At present, Castrada multispina is only known from Israel.

Diagnosis. Castrada species with an atrium copulatorium without a sphincter and a blind sac lined with dense arranged spines, larger (until 2.3 μm) in the distal region.

Figures

FIGURE 12: Castrada multispina sp. nov. A. Habitus. B. Male copulatory organ. C. Different kind of spines at the distal region of the blind sac.