Monnens M et al. (2019), Description and ecophysiology of a new species ...

ECB-ART-47356

Int J Parasitol Parasites Wildl 2019 Jul 10;10:71-82. doi: 10.1016/j.ijppaw.2019.07.005.

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Description and ecophysiology of a new species of Syndesmis Silliman, 1881 (Rhabdocoela: Umagillidae) from the sea urchin Evechinus chloroticus (Valenciennes, 1846) Mortensen, 1943 in New Zealand.

Monnens M , Frost EJ , Clark M , Sewell MA , Vanhove MPM , Artois T .

Abstract
A new rhabdocoel of the genus Syndesmis Silliman, 1881 (Umagillidae) is described from the intestine of the New Zealand sea urchin Evechinus chloroticus (Valenciennes, 1846) Mortensen, 1943a. This new species, Syndesmis kurakaikina n. sp., is morphologically distinct and can easily be recognised by its very long (±1 mm) stylet and its bright-red colour. In addition to providing a formal description, we present some observations on reproduction and life history of this new species. Fecundity is comparable to that of other umagillids and the rate of egg production and development increases with temperature. Hatching in this species is induced by intestinal fluids of its host. Relevant to global warming, we assessed the effect of temperature on survival, fecundity, and development. The tests indicate that Syndesmis kurakaikina n. sp. is tolerant of a wide range of temperatures (11-25 °C) and that its temperature optimum lies between 18.0 and 21.5 °C. Egg viability is, however, significantly compromised at the higher end of this temperature range, with expelled egg capsules often being deformed and showing increasingly lower rates of hatching. Given this, a rise in global temperature might increase the risk of Syndesmis kurakaikina n. sp. infecting new hosts and would possibly facilitate the spread of these endosymbionts.

PubMed ID: 31372337
PMC ID: PMC6658996
Article link: Int J Parasitol Parasites Wildl

Species referenced: Echinodermata
Genes referenced: LOC100887844 LOC592583

Article Images: [+] show captions


	Fig. 1. A. Specimen of E. chloroticus showing the horizontal plane of dissection. B. Urchin intestines containing flatworms (circled). C. Live specimen of Syndesmis kurakaikina n. sp., showing its bright-red colour. Scale bar: 1 mm. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
	Fig. 2. Schematic overview of the female reproductive system in Syndesmis. B: bursa, CGA: common genital atrium, EC: egg capsule, FA: female atrium, ID: insemination duct, MA: (entrance to) male atrium, Ov: ovary, Ph: pharynx, St: stylet, SR: seminal receptacle, U: uterus, V: vagina, Vit: vitellaria.
	Fig. 3. Syndesmis kurakaikina n. sp., holotype specimen whole-mounted in lactophenol. Differential-interference contrast. Scale bar: 250 μm. B: bursa, EC: egg capsule, FG: filament glands, In: intestine, Ov: ovaria, Ph: pharynx, St: stylet, SR: seminal receptacle, Vit: vitellaria.
	Fig. 4. Syndesmis kurakaikina n. sp., ciliated invagination at the anterior end in sagittal section. Scale bar: 50 μm. Br: brain.
	Fig. 5. Syndesmis kurakaikina n. sp. A. Sagittal section through pharynx and intestine. B. Camera-lucida drawing of the pharynx and associated glands. Scale bars: A = 100 μm, B = 50 μm. CM: circular muscles, FP: food particles, GS: granular secretion, In: intestine, LD: lipid droplets, LM: longitudinal muscles, N: nucleus, Oe: oesophagus, PhG: pharyngeal glands, PhL: pharyngeal lumen, RM: radial muscles, S: septum.
	Fig. 6. Syndesmis kurakaikina n. sp., reconstruction of the female reproductive system from a sagittally sectioned specimen. Male reproductive system omitted. Scale bar: 100 μm. B: bursa, BC: bursal canal (simplified), BV: bursal valve, CGA: common genital atrium, DC: ductus communis, EC: egg capsule, IC: insemination canal, In: intestine, FA: female atrium, FG: filament glands, Gp: gonopore, MA: (entrance to) male atrium, Ov: ovary, SRa: anterior part of seminal receptacle, SRp: posterior part of seminal receptacle, U: uterus, Vit: vitellaria.
	Fig. 7. Syndesmis kurakaikina n. sp., sagittal section through parts of the female reproductive system. Scale bar: 50 μm. B: bursa, DC: (entrance to) ductus communis, In: intestine, Ov: ovary, SRa: anterior part of seminal receptacle, SRp: posterior part of seminal receptacle, Vit: vitellaria.
	Fig. 8. Syndesmis kurakaikina n. sp., sagittal section through posterior body end, at genital pore. Scale bar: 50 μm. B: bursa, EF: egg filament, FA: female atrium, FG: filament glands, CGA: common genital atrium, Gp: gonopore, MA: male atrium, St: stylet, U: uterus, V: vagina.
	Fig. 9. Egg capsules of Syndesmis kurakaikina n. sp. A. Entire capsule bulb overlaid by part of the long filament. B. An egg capsule bulb in its entirety. C. Surface of capsule. D. Anterior and E. posterior parts of the egg filament. F. Anterior side of an egg capsule with hatching sutures just prior to opening. G. Broken capsule shell. Scale bars: A-B = 50 μm, C = 10 μm, D-E = 5 μm, F = 20 μm.
	Fig. 10. Reconstruction of the male reproductive system from a sagittally sectioned specimen of Syndesmis kurakaikina n. sp. Intestine and female reproductive system omitted. Stylet not drawn in its entirety. Scale bar: 200 μm. CGA: common genital atrium, ED: ejaculatory duct, Gp: gonopore, MA: male atrium, T: testis, SD: sperm duct, St: stylet, SV: seminal vesicle.
	Fig. 11. Stylet of Syndesmis kurakaikina n. sp. A. Projection of 36 interference-contrast photographs at different focal depths. B. Camera-lucida drawing of this stylet. Scale bar: 50 μm.
	Fig. 12. Syndesmis kurakaikina n. sp. A. Mature specimen. B. Posterior end of live mature specimen in the process of laying an egg capsule. C. Entire egg capsule, showing the bulb containing two embryos and the long filament. D. Opened, empty egg capsule post-hatching after two weeks incubation at 21.5 °C. E-G. Photomicrographs showing the development from eggs (after one week incubation, E), through zygote (after two weeks incubation, F) to fully developed embryo (after four weeks incubation, G) in an egg capsule from the 14.5 °C treatment. H–I. Non-viable (H) and deformed (I) egg capsules from the 25 °C treatment. E: egg, EC: egg capsule, EF: egg filament, Em: embryo, Gp: gonopore, Ph: pharynx, Vit: vitellaria, Z: zygote. Scale bars: A = 1 mm, B–C = 100 μm, D-I = 50 μm.
	Fig. 13. Number of egg capsules produced by four specimens of Syndesmis kurakaikina n. sp., when incubated at five different temperatures (11.0, 14.5, 18.0, 21.5, and 25.0 °C). Endosymbionts were collected at four different times throughout the year (autumn, early winter, late winter and spring). 95% confidence intervals are provided.

References [+] :

Altizer, Climate change and infectious diseases: from evidence to a predictive framework. 2013, Pubmed