Spirinia parasitifera ( Bastian, 1865 )

Armenteros, Maickel, Ruiz-Abierno, Alexei & Decraemer, Wilfrida, 2014, Revision of Desmodorinae and Spiriniinae (Nematoda: Desmodoridae) with redescription of eight known species, European Journal of Taxonomy 96, pp. 1-32 : 21-24

Spirinia parasitifera ( Bastian, 1865)

Figs 11 , 12 , Table 2

Spira parasitifera Bastian, 1865: 159 .

Spiliphera oxycephala Bütschli, 1874: 47 .

Spirinia nidrosiensis Allgén, 1933: 60 .

Material examined

2 ♂♂, 2 ♀♀ and 3 juveniles, deposited in the nematode collection at Centro de Investigaciones Marinas, Universidad de La Habana, CUBA.

Description

Cuticle finely striated in the anterior region (annuli ~ 1 μm width) but even narrower in the mid-body and tail region. Inner and outer labial sensilla papilliform (1–2 μm long), four cephalic setae (7–10 μm long) at level of amphidial fovea. Amphidial fovea cryptospiral located forward in the head (<6 μm from apex). Eight longitudinal rows of somatic setae decreasing in length from the cervical region (7–10 μm long) to papillae at mid-body and tail region. Pharynx muscular with posterior bulb and internal lining sclerotized. Cardia inconspicuous. Secretory-excretory system not observable. Tail conical, last portion without striations.

Male monorchic; spicules strongly bent, with capitulum, gubernaculum a bent rod dorsally oriented; without precloacal supplements.

Female didelphic, amphidelphic with reflexed ovaries, vulva a transversal aperture.

Juveniles are similar to adults, except for the development of the reproductive system.

Remarks

S. parasitifera is a cosmopolitan species recorded from several habitats and biogeographical regions. Coles (1987) noted that the main differences among populations from widely divergent coasts ( England, Canada and USA) were the shape of the proximal end of the spicules and the body size. He reported that specimens from warmer waters (Florida) had smaller body size (males: 1650–2150 µm; females: 1650–1910 µm) compared to specimens from temperate waters (males: 2000–3300 µm; females: 2020–3180 µm). However, our specimens from a tropical area (Caribbean Sea) had body size closer to those from colder waters (males: 1854–3570 µm; females: 2803–3796 µm). Therefore, a negative relationship between water temperature and body size is not plausible for this species. For some species we studied in this paper this negative relationships is supported (e.g., Acanthopharynx denticulatus , Paradesmodora immersa ) but not for other (e.g., Spirinia parasitifera , Chromaspirina inaurita ). The considerable geographic variation in the morphology of S. parasitifera suggests the existence of cryptic species within this nominal species.

Another rare sympatric species, belonging to the genus Spirinia , has been recorded in our samples with only two specimens. The species was characterized by the small body size (male: 686 µm; female: 684 µm) and two kinds of somatic setae (long: 28–35 μm and short 5–8 μm). It is closer to S. gnaigeri Ott, 1977 (Ott 1977: 134) ; however, body size of type specimens in Ott (1972) is larger (males: 860– 913 µm; females: 836–955 µm) and the length of both somatic setae shorter (long setae: 20–22 µm; short setae: 4–5 µm). However, more specimens should be examined in order to evaluate if this is really a new species of Spirinia .

Figures

Fig. 11. Spirinia parasitifera (Bastian, 1865). A. Anterior region of a juvenile. B. Posterior region of ♂.

Fig. 12. Spirinia parasitifera (Bastian, 1865), SEM microphotographs of ♂ (A, B & C) and ♀ (D). A. Head in frontal view. B. Head in lateral view. C. Anal region with portion of protruding spicule. D. Vulva.