Carcinonemertes sebastianensis, Santos & Norenburg & Bueno, 2006

Santos, Cynthia, Norenburg, Jon L. & Bueno, Sérgio L. S., 2006, Three new species of Carcinonemertes (Nemertea, Carcinonemertidae) from the southeastern coast of Brazil, Journal of Natural History 40 (15 - 16), pp. 915-930 : 922-925

Carcinonemertes sebastianensis new species

( Figures 3 , 4A–E and 5A, B )

Diagnosis

Body color translucent white. Two eyes, brown. Anterior and posterior end of body rounded. Worms 2.0–11.0 mm long. Accessory stylets absent. Ovaries arranged in one row on each side of intestine. Distance from first ovary to tip of head 1250–2000 mm. Takakura’s duct present. Ornamented and filiform mucus sheath may be present in adult worms.

Material examined

Four females, six males, 12 eggs and one larva were examined. Holotype: male, from the egg mass of Menippe nodifrons ; type locality: Figueira Beach , São Sebastião, Brazil, (23 ° 449560S, 45 ° 249340W); 22 January 2004; Coll. Cynthia Santos; MZUSP No. 005. Paratype: female, from the egg mass of M. nodifrons ; type locality: Figueira Beach, São Sebastião, Brazil, (23 ° 449560S, 45 ° 249340W); 22 January 2004; Coll. Cynthia Santos; MZUSP No. 006 .

Etymology

The species name is an adjective in feminine singular and is in recognition of the locality where the host crab was found, São Sebastião.

Description

The description is based on living adults, eggs and larva. Measurements are given in mean¡SE (range, number of specimens observed).

Female. Body color translucent white; gut varied from orange to brownish; gonads translucent white. Two eyes, brown, circular or elliptical. Found free among egg mass of host or in a filiform, ornamented mucus sheath. Irregular lapilli on the mucus sheath ( Figure 3 ); lapilli with concentric lines ( Figure 4A ). Anterior ( Figure 4B ) and posterior end of body rounded. Dimensions of relaxed worms were 7.0¡4.0 mm (3.0–11.0 mm; n 52) long and 405¡ 62 mm (230–500 mm; n 54) wide. Eye 14¡ 2 mm (10–18 mm; n 54) long and 9¡ 1 mm (8–12 mm; n 54) wide. Distance between eyes 131¡ 14 mm (102–160 mm; n 54). Distance from eyes to tip of head 110¡ 18 mm (70–150 mm; n 54). Brain 99¡ 6 mm (88– 110 mm; n 53) long and 64¡ 4 mm (58–72 mm; n 53) wide. Distance from brain to tip of head 150¡ 23 mm (100–210 mm; n 54). Proboscis bent on itself. Anterior proboscis chamber could not be distinguished. Diaphragm 51¡ 2 mm (48–58 mm; n 54) long and 56¡ 3 mm (50–62 mm; n 54) wide. Single stylet on basis 9¡ 1 mm (8–10 mm; n 54) long. Stylet basis 22¡ 1 mm (20–25 mm; n 54) long and 8¡ 1 mm (8–10 mm; n 54) wide ( Figure 4C ). Stylet:basis ratio 0.416 (0.375 –0.444; n 54). Distance from central stylet to tip of head 208¡ 28 mm (170–290 mm; n 54). Accessory stylets absent. Proboscis bulb 34¡ 4 mm (28–42 mm; n 54) long and 38¡ 4 mm (30–42 mm; n 54) wide. Posterior proboscis could not be visualized. Ovaries arranged in one row on each side of the intestinal diverticula. Distance from first gonad to tip of head 1700¡ 167 mm (1250– 2000 mm; n 54) ( Figure 4B ).

Male. Body color translucent white; gut yellow; gonads translucent white. Two eyes, brown, circular or elliptical; elliptical eyes the most common shape. Found free among egg mass of host or in a filiform, ornamented mucus sheath. Irregular lapilli on mucus sheath ( Figure 3 ); lapilli with concentric lines ( Figure 4A ). Anterior and posterior end of body rounded ( Figure 4D, E ). Dimensions of relaxed worms 6.2¡ 1.4 mm (2.0– 11.0 mm; n 56) long and 362¡ 28 mm (280–480 mm; n 56) wide. Eye 15¡ 1 mm (12– 18 mm; n 56) long and 10¡ 1 mm (5–12 mm; n 56) wide. Distance between eyes 110¡ 5 mm (90–120 mm; n 56). Distance from eyes to tip of head 112¡ 11 mm (80– 150 mm; n 56). Brain 101¡ 10 mm (75–125 mm; n 55) long and 52¡ 3 mm (42–62 mm; n 55) wide. Distance from brain to tip of head 150¡ 13 mm (112–200 mm; n 56). Proboscis bent in on itself. Anterior proboscis chamber could not be distinguished. Diaphragm 46¡ 2 mm (40–50 mm; n 56) long and 48¡ 1 mm (45–50 mm; n 56) wide. Single stylet on basis 11¡0 mm (10–12 mm; n 56) long. Stylet basis 25¡ 1 mm (22– 30 mm; n 56) long and 10¡0 mm (8–10 mm; n 56) wide ( Figure 4C ). Stylet:basis ratio 0.431 (0.333 –0.556; n 56). Distance from central stylet to tip of head 206¡ 24 mm (150–280 mm; n 55). Accessory stylets absent. Proboscis bulb 30¡ 2 mm (25–38 mm; n 56) long and 36¡ 2 mm (32–40 mm; n 56) wide. Posterior proboscis 128¡ 18 mm (100– 160 mm; n 53) long and 43¡ 9 mm (25–55 mm; n 53) wide. Seminal vesicle not visible under stereomicroscope, but could be seen under compound microscope in some specimens.

Egg. Color white. Egg strings ( Figure 5A ) found in a firm and transparent sheath. Developing eggs 86¡ 2 mm in diameter (75–100 mm; n 512). Egg strings 232¡ 14 mm (180– 260 mm; n 55) wide. Number of eggs per egg string 386¡66 (320–451; n 52). Number of rows of eggs per egg string 3¡0 (n55).

Larva. Body ciliated with anterior and posterior ciliary tufts. Body shape ovoid. Two eyes. Body length 92 mm (n 51). Body width 62 mm (n 51).

Infestation site

Adult worms were found in the host’s egg mass (ovigerous females with eggs in initial, intermediate and final stages of development). All immature worms were found encysted in a mucus sheath without ornamentation in the following sites: on the ventral side of the abdomen, on the setae that follow the border of the abdomen, on the central axis of pleopods ( Figure 5B ), and on the setae of pleopods of non-ovigerous adult female crabs; on the ventral side of the abdomen, on the central axis of pleopods, and on the setae of pleopods of ovigerous females; at the ventral side of the abdomen, on the central axis of pleopods, and on the setae of pleopods of post-ovigerous females. No immature worms were found on male crabs.

Figures

Figure 3. Scanning electron micrograph of the lapilli of the mucus sheath produced by the adults of Carcinonemertes sebastianensis n. sp.

Figure 4. Carcinonemertes sebastianensis n. sp. (A) Detail of lapilli of adult mucus sheath. (B) Rounded anterior end of female, showing the great distance from first gonad to tip of head. (C) Stylet and basis (arrow) in a female worm. (D) Anterior end of male. (E) Posterior end of male. Abbreviations: b, proboscis bulb; d, diaphragm; g, gonad.

Figure 5. Carcinonemertes sebastianensis n. sp. (A) Egg strand (arrow) on Menippe nodifrons eggs. (B) Juvenile worms encysted (arrows) on the axis of the pleopod of Menippe nodifrons.