Pheronous donghaiensis, Chen, Yu Zhen & Guo, Yu Qing, 2015

Chen, Yu Zhen & Guo, Yu Qing, 2015, Three new and two known free-living marine nematode species of the family Ironidae from the East China Sea, Zootaxa 4018 (2), pp. 151-175 : 156-160

Pheronous donghaiensis sp. nov.

( Figure 4 , Figure 5 , Table 2)

Type material. ♂1, ♂2, ♂3, ♀1 were collected from Station XMHC H 1 in June 2011, and ♂4, ♂5, ♂6, ♂7, ♂8, ♀2, ♀3 from Station ZZDS H1, H2, H 3 in July 2012 and May 2013.

Holotype, ♂1 on slide number XMHC 20110622 H104. Paratypes: ♂2 on slide number XMHC 20110622 H101, ♂3 on slide number XMHC 20110622 H110, ♂4 and ♀2 on slide number ZZDS 20130518 H3U102, ♂5 on TABLE 2. Individual measurements οf Pheronous donghaiensis sp. nοv. (in μm) Characters Hοlοtype Paratypes Specimens frοm Statiοn ∶ XMHC Specimens frοm Statiοn ∶ ΖΖDS slide number ZZDS 20120707 H1U001, ♂6 on slide number ZZDS 20120707 H1U103, ♂7 on slide number ZZDS 20120707 H1U102, ♂8 on slide number ZZDS 20130518 H2D114, ♀1 on slide number XMHC 20110622 H123, ♀3 on slide number ZZDS 20120707 H2D001.

Type locality and habitat. All specimens were collected from intertidal sandy sediments on the Huangcuo coast, Xiamen City and Dongshan Island, Zhangzhou City, East China Sea. Characteristics of surface sediment: Station XMHC: 118°09′ E, 24°26′ N, Silt+clay: 0.06%; Salinity: 28‰; organic matter: 0.0011%; Chlorophyll a: 0.0042 µg·g-1; Phaeopigments: 0.0098 µg·g-1. Station ZZDS: 117.4836°E, 23.7081°N. Silt+clay: 3.27%.

Etymology. This species is named for the type locality: intertidal sediments from the East China Sea.

Measurements (Table 2)

Description. Specimens from Station XMHC Male. Body tapering acutely at posterior extremity. Cuticle smooth and thick, with several small scattered conical papillae which are sometimes associated with more or less marked elevations of the cuticle. Head distinctly set off from the remainder of the body by a deep groove. Head sensilla papilliform, in two circles of 6 + (6 + 4). Inner labial sensilla small; six outer labial sensilla and four cephalic sensilla in a circle, stout and blunt, situated at the base of head region, outer labial sensilla are slightly larger than cephalic sensilla. Amphids pocket-shaped, about 0.59–0.62 cbd and with anterior edges lying exactly on the posterior edge of the cephalic groove. Buccal cavity divided into an anterior cup-shaped section and a posterior strongly cuticularized tubular section, length 5–8 µm and 55–56 µm respectively. The inner wall of the cup-shaped section armed with rows of minute denticles. Two smaller dorsal and two larger subventral solid curved teeth present at the margin of the anterior cup-shaped section and the posterior tubular section. Pharynx about 0.16 times of body length, slightly swelling in stomatal region and gradually enlarging posteriorly, corresponding body diameter 52–55 µm at posterior extremity. Сardia bluntly conical, surrounded by intestinal tissue. Excretory pore opening at the labial region between the labial papillae and the cephalic sensilla. Ventral gland lies posterior to the pharynx. Tail tapers to a sharp point, without caudal glands and with a series of three pairs of symmetrical or asymmetrical small conical papillae in two rows distributed in the postcloacal subventral sector. There are also two rows of asymmetrical small conical papillae present on the precloacal subventral sector, each row containing 8–9 papillae. All of the small conical pre- and post-cloacal papillae are associated with more or less marked elevations of the cuticle.

Reproductive system diorchic with two opposed testes, situated to right of intestine. Spicules paired and stout, with central septum at proximal end. Gubernaculum relatively short and slightly thinner proximally, distal end thick and developed into two claw-like structures.

Female. Similar to male in most aspects, except body slightly shorter (1932 µm vs. 2024–2188 µm); amphid relatively smaller (0.55 cbd vs. 0.59–0.62 cbd); pharynx relatively longer (b 5.8 vs. 6.3–6.4); tail longer (c ’ 4.0 vs. 2.4–2.8; c 16.5 vs. 22.8–25.0); tail with several irregularly scattered papillae, while the two rows of precloacal and postcloacal subventral papillae which regularly exist in males are absent in female caudal region.

Reproductive system didelphic, ovaries opposed and reflexed, located at right side of intestine. Vulva situated at about 60.1% of body length.

Specimens from Station ZZDS. Similar to specimens from Station XMHC in morphology, except body much smaller (male 1293–1427 µm vs. 2024–2188 µm; female 1332–1417 µm vs. 1932 µm); amphids relatively bigger (0.67–0.79 cbd vs. 0.59–0.62 cbd), female tail relatively shorter (c’ 3.0–3.5 vs. 4.0; c 16.9–17.5 vs. 16.5), male pharynx slightly longer (b 5.7–6.1 vs. 6.3–6.4) and the precloacal papillae fewer (3–4 vs. 8–9).

Diagnosis and discussion. The genus Pheronous was set up by Inglis in 1966 with the type species Pheronous ogdeni . It differs from other genera of Ironidae by the papilliform head sensilla; the pointed tail and the absence of caudal glands, ect. ( Inglis 1966; Platt & Warwick 1983). So far, only one species has been described in this genus ( Gerlach & Riemann 1974, Electronic database: http://www.marinespecies.org/index.php; http://nemys.ugent.be;). A pictorial key including P. ogdeni and the newly described species is given in Figure 6.

Pheronous donghaiensis sp. nov. is characterized by the combination of the following characters: tail tapers to a sharp point; caudal glands absent; in the male the tail bears two rows of small conical papillae which are associated with more or less marked elevations of the cuticle; buccal cavity armed with four large solid teeth and rows of minute denticles. It can be distinguished from P. ogdeni , the sole other species of Pheronous by body size; the number, shape and arrangement of subventral precloacal papillae (asymmetrical vs. paired); the shape of spicule (stout, with central septum at proximal end vs. stout and clumsy, sometimes appears to present a dorsal strengthened rib) ( Inglis 1966).

Figures

FIGURE 4. Pheronous donghaiensis sp. nov. A: lateral view of female anterior part; B: female reproductive system; C: lateral view of female tail region; D: lateral view of male posterior part; E: lateral view of male anterior part; F: lateral view of male copulatory apparatus; G: lateral view of male head. Scale bar: 50 Μm.

FIGURE 5. Pheronous donghaiensis sp. nov. A: lateral view of female head end, showing buccal cavity and teeth; B: lateral view of male head end, showing cephalic sensilla and amphid; C: lateral view of female body part, showing vulva; D: lateral view of male body part, showing copulatory apparatus; E: lateral view of mail tail region; F: lateral view of female tail region. Scale bar: A ~ D = 10 Μm; E – F = 25 Μm.