Zalonema mariae, Larrazábal-Filho, Alexandre L., Silva, Maria Cristina Da & Esteves, André M., 2015

Larrazábal-Filho, Alexandre L., Silva, Maria Cristina Da & Esteves, André M., 2015, Four new species of free-living marine nematodes of the family Desmodoridae (Nematoda: Desmodorida) and a redescription of Desmodora nini (Inglis, 1963) from the continental shelf off northeastern Brazil, Zootaxa 4021 (1), pp. 63-92 : 71-75

Zalonema mariae sp. n.

(measurements in Table 3 , Figs 5 , 6 and 7 ).

Type material: Holotype Male adult, MNRJ 344 (03°30’00”S, 038°15’00”W) collected in June 2009, in the Potiguar Basin, between 45 and 100 m deep. Sediment: fine to coarse bioclastic sand.

Paratype female: adult, MNRJ 345 (04°45’00”S, 036°30’00”W) collected in June 2009, in the Potiguar Basin, between 45 and 100 m deep. Sediment: terrigenous muds.

Other paratypes: 24 females (169-173 LMZOO-UFPE), 18 males (164-168 LMZOO-UFPE), 1 J2 (174 LMZOO-UFPE) and 8 J1 (175 LMZOO-UFPE) collected on the same date as the holotype.

Etymology. The species name is a tribute to Professor Maria Eduarda Larrazábal, the first author’s aunt.

Description. Holotype male ( Figs 5 , 7 ) Body long and cylindrical, yellowish brown, with strong cephalic capsule and conical tail. Cuticle annulated except on head capsule and final portion of tail. Short somatic setae arranged in six longitudinal rows: two dorsal, two lateral and two ventral. Rounded triangular head and long cephalic capsule. Fovea amphidialis spiral (3.5 turns). Buccal cavity relatively long, with two dorsal teeth, one after the other, six lips with 12 folds. Anterior sensilla arrangement: six inner labial sensilla, six long outer setae, four cephalic setae above the fovea amphidialis, and base of cephalic capsule with ring of four small subcephalic setae. Pharynx with pyriform endbulb, with cuticularized lumen divided into distinct regions. Nerve ring surrounds pharynx, position variable, present in mid pharynx-length or region closest to head. Ventral gland and secretoryexcretory pore not observed. Cardia inserted in intestine. Reproductive system with outstretched testis. Spicules strongly sclerotized, containing rounded capitulum and broad velum. Gubernaculum simple, lacking apophysis. Lateral alae present in posterior region ( Fig. 7 I), accounting for 25% of total body length. Ventral ala measuring 435.5 µm. Three caudal glands. Tail conical, with elongated non-annulated tail end and spinneret.

Female ( Figs 5 , 6 ) Similar to male. Sexual dimorphism consisting of absence of ventral and lateral alae and number of turns of fovea amphidialis (fewer in female, with 2.5 turns). Vulva as transverse slit. Vagina vera short, vagina uterina with sphincter muscle. Egg found in anterior uterus ( Fig. 6 D). Short conical tail.

Juveniles. Eight juveniles were found in the first stage of development ( Fig. 7 ), and one juvenile in the second stage. In the second-stage juvenile it was not possible to observe intestinal walls. The juveniles are morphologically similar to the female.

Diagnosis and relationships. Zalonema mariae sp. n. is characterized by its multispiral fovea amphidialis (3.5 turns). The buccal cavity is relatively long, with two dorsal teeth, one posterior to the other. Lateral alae present on each side of body, and ventral ala.

Zalonema vicentei sp. n. is similar to Zalonema mariae sp. n. The similarities are: the fovea amphidialis (multispiral, containing 3.5 turns in males and 2.5 in females); arrangement of setae; spicules with rounded capitulum and broad velum; gubernaculum; tail conical; and lateral alae and ventral ala. They are differentiated by: Z. vicentei sp. n. has a long buccal cavity with two small teeth (one dorsal and one ventral), while Z. mariae sp. n. has two dorsal teeth, one posterior to the other. In addition, the endbulb is flattened in Z. vicentei sp. n. and pyriform in Z. mariae sp. n.

The main feature separating the two species is the number and position of the teeth. Zalonema mariae sp. n. has two dorsal teeth. A buccal cavity with two or three teeth is considered a characteristic of the family Desmodoridae , and varies with respect to the presence of one or two subventral teeth ( Decraemer & Smol 2006). Here we report for the first time the presence of two dorsal teeth in a member of the subfamily Desmodorinae .

Figures

FIGURE 5. Zalonema mariae sp. n. Paratype female MNRJ 345 A: overview. B: cephalic region, emphasizing the two dorsal teeth. C: tail region. D: vulva opening. Holotype MNRJ 344 - E: copulatory apparatus. F: fovea amphidialis. G: left lateral ala. H: overview (male).

FIGURE 6. Zalonema mariae sp. n. Paratype female MNRJ 345 - A: overview. B: anterior region. C: posterior region. D: ovary and vulva opening. E: head region.

FIGURE 7. Zalonema mariae sp. n. Holotype MNRJ 344 - A: overview. B and D: head region. C: anterior region. F: posterior region. E: copulatory apparatus. I: ventral ala and lateral alae. Paratype – G: overview (Juvenile I) and H: overview (Juvenile II).

Tables

TABLE 3. Measurements (µm) of Zalonema mariae sp. n. in the Potiguar Basin, Brazil. n = number of specimens; * = not applied. Abbreviations as in Table 1.

	Male Holotype n = 1	Male Paratypes n = 18	Female Paratype n = 1	Female Paratypes n = 24	Juvenile Paratypes n = 9
L ph nr	1785 222 56.5	(1080–2640) (141–331.5) (91–163)	1155 174 87	(936–2580) (133–279) (92–167)	(650–1391) (130–190.5) (69–106.5)
mbd abd t	75 54 90	(40–84) (34.5–82.5) (60–100.5)	55.5 24 102	(48–118) (22–58) (69–151)	(31–47) (20–36.5) (73–109)
tf hd cap.ceph	18 31.5 31.5	(13.5–18) (24–35) (15–27)	19 30 19	(18–51) (24–45) (19–35)	(19–24) (17–22) (13–18)
at spic gub	3.5 76.5 25.5	3.5 (39–75) (18–43.5)	2.5 * *	2.5 * *	2.5 * *
Alae Velum T	435.5 49.5 756	(279.5–591.5) (18–65) (634–1950)	* * *	* * *	* * *
ext. lab. cs subc s.	5.5 7 4	(3–4) (5–9) (3–5.5)	4 7 3.5	(3–4.5) (4–7) (3.5–7)	(3.5–7) (4–7) (3–4)
annul % bulb % amph	3 70 52	(3–4) (64–82) (32–61)	3 71 30	(3–4) (71–82) (22–46)	(3–5) (62–81) (33–44)
ov v v (%)	* * *	* * *	477 555 48	(370–902) (279–1275) (49–69)	* * *
a b c	24 8 29	(22.5–35) (6–9.5) (15–25)	21 6.5 11	(19–28) (6–10) (11–15)	(17–29) (5–8) (7–14)
c'	2	(1.5–3)	4	(2–4)	(2.5–4)