Carcinonemertes kurisi, Sadeghian & Santos, 2010

Sadeghian, Patricia S. & Santos, Cynthia, 2010, Two new species of Carcinonemertes (Hoplonemertea: Carcinonemertidae) living in association with leucosiid crabs from California and Tasmania, Journal of Natural History 44 (37 - 40), pp. 2395-2409 : 2397-2402

Carcinonemertes kurisi sp. nov.

Carcinonemertes sp. A .- Sadeghian and Kuris 2001: 59–63; fig. 1; Carcinonemertes new species A – Sadeghian, 2003.

Type material

Holotype. Male worm, cross-sectioned. SBMNH 348115 , 17 slides.

Paratype. Male worm, cross-sectioned. USNM 1122564 , 14 slides .

Type locality

Northeast Pacific Ocean, USA, California, Santa Barbara County, Goleta Bay , off Sands Beach , 34 ◦ 26 ′ N, 119 ◦ 54.9 ′ W. 6 m depth; sandy bottom .

Material examined

A total of 30 ovigerous females, 18 post-ovigerous females, and 16 males of Randallia ornata were examined in preparing this description. A total of 363 live worms were recovered and examined.

Diagnosis

Sexually mature adults filiform, length to 10 mm; males smaller than females. Proboscis chambers aligned in same plane; anterior chamber to 77 µm long by 46 µm wide; posterior chamber to 123 µm long by 16 µm; armature small; stylet to approximately 5 µm long, proximal end enlarged where attached to basis; basis ovoid, to 20 µm long by 7 µm wide. Submuscular glands open to body surface by large number of separate ducts throughout body. Mucus sheath present, non-ornamented, with distinctive spiral or corkscrew shape. Intestine with deeply lobed diverticula. Sexes separate; ovaries regularly distributed as a single row on each side, between intestinal diverticula, ovarian pores indistinct; testes abundant, irregularly scattered throughout body posterior to brain/stomach; Takakura’s duct present, diameter to 19 µm. Newly hatched planuliform larvae round, 50 µm in diameter.

Description

Sexually mature adult worms. Inhabit sheaths attached to setae of pleopods or abdominal surfaces of crab ( Figure 1A ). Body entirely ciliated, filiform (when extracted from corkscrew-shaped sheath), slightly flattened; head rounded without cephalic furrows; tail rounded; anterior end of worm slightly narrower than posterior end. Length of adult females from 1.0 to 10.0 mm (4.5 ± 0.3 mm; n = 40) ( Figure 1B ); adult males from 0.7 to 3.5 mm (1.8 ± 0.1 mm; n = 36) ( Figure 1C ). Two ocelli present; brown, irregularly shaped; diameter about 31 µm. Ocelli located approximately 75 µm from anterior end; distance between ocelli ranges from 119 to 262 µm (122 µm; n = 4). Colour of live females dark orange to reddish pink; males whitish pink; in both sexes anterior region darker than posterior region. Preserved worms opaque white.

Sheath. Tubular, open at one end, mucoid, distinctive corkscrew shape ( Figure 1A–C ), non-ornamented, slightly longer than worm. Wall of sheath 7.4 µm thick.

Proboscis complex. Proboscis with three distinct chambers, oriented in straight line; located next to stomach ( Figure 2C ). Length of anterior proboscis chamber 77 µm, middle chamber (proboscis bulb) 46 µm; posterior chamber 123 µm; width from 7 to 15 µm. Stylet short, length 5 µm; slightly inflated posteriorly where attached to basis. Basis ovoid, rounded posteriorly; length 20 µm (19–22 µm; n = 9), width 7 µm ( Figure 2D ). Ratio of stylet length to basis length, 1: 0.247. Accessory pouches and reserve stylets not present.

Body wall. Epidermis up to 9.0 µm thick, consists of single layer of ciliated columnar cells. Dermis (= connective tissue) very thin, less than 1.0 µm. Two muscle layers present: outer circular, inner longitudinal. In region of intestine and gonads, circular muscle layer 9.8 µm thick; longitudinal muscle layer 12.2 µm thick.

Glandular cells. Submuscular glandular cells (= hypodermal glands of Humes, 1942) are vacuolated, containing acidophilic elements, present in large numbers beneath body wall musculature 45 µm thick; open to body surface through ducts; diameters of ducts range from 15 to 20 µm. Anteriorly, glandular cells merge into clusters of large, well-developed cephalic glands ( Figure 2B ). Parenchymatous connective tissue sparsely developed in cerebral region.

Digestive tract. Rhynchodeum thin-walled, with ventral subterminal pore. Foregut includes a short oesophagus that opens to the folded and glandular stomach (diameter to 20 µm), both ciliated. Intestine tubular, with deeply lobed lateral diverticula; anus terminal, opens into cloaca in males.

Vascular system. Lateral vessels extend through the entire length of body; adjacent to main longitudinal nerve cords; pass through the brain ring anteriorly and anastomose as the cephalic loop, posteriorly by the supraintestinal connective. Mid-dorsal vessel absent.

Nervous system. Brain small, simple; dorsal and ventral lobes present ( Figure 2A ). Neuroganglionic tissues surround the cerebral ganglia, connected to outer tissue neurilemma.

Reproductive organs. Sexes separate. In mature males, testicular field begins immediately posterior to the cerebral region. Testes ovoid, diameter to 56 µm ( Figure 3A ); scattered irregularly throughout body between intestinal wall and submuscular glands; extend posteriorly to the seminal vesicle. Takakura’s duct present, diameter to 18.8 µm; duct may be packed with mature spermatozoa ( Figure 3B,C ).

In mature females, ovaries are dorsoventrally elongated; length 122 µm; each ovary alternating with lateral intestinal diverticula; single row on each side of body; ovarian pores indistinct. Eggs spawned by female are enveloped in a cylindrical strand of gelatinous material; egg strands are laid within the egg mass brooded by the host; diameter of egg strands 300 µm ( Figure 3D ). Eggs pink; diameter ranges from 87 to 106 µm (90.0 µm; n = 30).

Larvae and juveniles. Newly hatched larvae ovoid; 50 µm in width; translucent white. Length not measured. Juvenile worms encyst on gill lamellae of crab host. Cysts ovoid; lengths 0.95–2.09 mm (1.5 ± 0.13 mm; n = 7), widths 0.76–1.14 mm (0.93 ± 0.20 mm; n = 7). Juveniles visible through translucent cyst wall.

Dormant adults. Post-reproductive, adult worms located on pleopods, sternites and under abdomen of crab host; filiform, half as long as sexually reproductive worm. Dormant adults occupy tough, c-shaped translucent capsules; sex organs regressed. Colour of worm dark orange to fuchsia.

Host geographic distribution

Northeast Pacific Ocean; Mendocino County California to Bahia Magdalena , Baja California, USA .

Etymology

This species is named in honour of Dr Armand M. Kuris, Professor of Biology at the University of California, Santa Barbara, for his tremendous support and enthusiasm toward the study of nemertean egg predators.

Figures

Figure 1. Carcinonemertes kurisi sp. nov. (A) Worms in excised egg mass; (B) reproductive female; (C) mature male. Scale bars 1 mm.

Figure 2. Histological sections of Carcinonemertes kurisi sp. nov. (holotype SBMNH 348115). (A) Longitudinal frontal section showing dorsal brain lobe and neuroganglionic tissues; (B) longitudinal frontal section through cephalic glands; (C) longitudinal sagittal section showing proboscis alignment (three arrows); (D) live squash preparation of stylet (arrow) and basis. Length of stylet approximately 5 µm. Scale bars: A, B = 50 µm; C = 10 µm. Abbreviations: BL, brain lobe; ST, stomach; NT, neuroganglionic tissues; CG, cephalic glands; IL, intestinal lumen; SG, submuscular glands.

Figure 3. Histological sections of Carcinonemertes kurisi sp. nov. (A) Cross-section showing testes; (B,C) sperm packed Takakura’s duct system; (B) ducts in context of whole worm; (C) detail of duct; (D) in situ photograph of egg strands (arrows) within egg brood of crab host. Diameter of strands approximately 300 µm. Scale bars: A, B = 50 µm; C = 10 µm. Abbreviations: T, testis; TD, Takakura’s duct.