Description of a Marine Nematode Hopperia sinensis sp. nov. (Comesomatidae) from Mangrove Forests of Quanzhou, China, with a Pictorial Key to Hopperia Species

GUO Yuqing, CHANG Yu, CHEN Yuzhen, LI Yongxiang, and LIU Aiyuan



Description of a Marine Nematodesp. nov. (Comesomatidae) from Mangrove Forests of Quanzhou, China, with a Pictorial Key toSpecies

GUO Yuqing1), *, CHANG Yu1), CHEN Yuzhen1), LI Yongxiang1), and LIU Aiyuan2)

1),,,361021,2),,361021,

A new free-living marine nematode speciessp. nov. from mangrove forests of Fujian Province, China, is identified and illustrated.sp. nov. is characterized by its cephalic setae 2.4–2.8μm long or 17%–20% head diameter, and amphids of 2.25–2.5 turns. Lateral differentiation appears with larger, more irregularly distributed dots behind 3–5 transverse rows of dots posterior to amphid. Buccal cavity is consisted of a shallow and weakly sclerotized cup-shaped portion with strongly sclerotized walls of 18–21μm deep. There are three sclerotized and size-equally pointed teeth at the junction between the two parts. Spicules of 41–45μm long are slightly curved with broadband velum and central strips at the proximal end. The gubernacula, with apparent lateral guiding pieces, are formed by one central tubular piece that is weakly sclerotized with 11–16μm long dorso-caudally directed apophyses. There are 13–14 fine tubular precloacal supplements. Conico-cylindrical tail gradually tapers till pointed tail tip. Female is similar to male, but have a longer body and tail. Ovaries are opposed and outstretched, with anterior ovary to the left and posterior ovary to the right of the intestine. A pictorial key to all the valid known species in genusis given.

free-living marine nematode; new species;;East China Sea; mangrove

1 Introduction

Mangrove forestsgrow in 123 countries, occupying more than 150000km2. They mostly distribute in tropical and subtropical environments, and can also be found in some temperate locations (Krauss and Friess, 2011). Fujian is the most northern province of China’s natural mangrove distribution, and also one of the earliest provinces of constructing mangrove forests in China. Mangroves are unique in biodiversity, but studies on their meiobenthic biodiversity are scarce in China (Liu and Huang, 2012). In contrast, in other parts of the world, researches on meiofauna in mangroves were active in last 10 years. For example, in Vietnam, over 40 species of new free-living marine nematodes are discovered. In October 2012 and January and April 2013, a transect at the estuary of the Luoyang River, Quanzhou district was investigated for the meiofauna, mainly the free-living marine nematodes, the most dominant group of the mangrove forest of(Linn.) (Chang and Guo, 2014). Four species were previously found in the muddy sediment in mangroves forest, includingGagarin & Thanh, 2006,Gagarin and Thanh, 2006,Gagarin and Thanh, 2006 andJensen, 1992. The present paper describes one new species of free-living marine nematodes, belonging to the genusVitiello, 1969.

2 Materials and Methods

Undisturbed sediment samples were taken from Luoyang River estuary mangrove forest of Quanzhou City. The samples were fixed with 5% formalin in seawater. In laboratory, the samples were stained with rose Bengal for more than 24h. Nematodes were extracted by Ludox centrifugation (Warwick., 1998). Each sample was washed and put into a lined Petri dish, and the meiofauna were sorted out under a stereoscopic microscope to higher taxonomic levels. Nematodes were transferred into a solution containing, by volume, 90% freshwater, 5% of the 95% ethanol and 5% of glycerol in a cavity block, allowing the ethanol slowly evaporates. The description has been made from glycerin mounts under interference contrast microscopy (NIKON 80i). Drawing was made with the aid of a camera lucida. Type specimens have been deposited in the Institute of Oceanology, Chinese Academy of Sciences.

Measurements are in µm. Abbreviations are as follows: a means total body length/maximum body diameter; b means total body length/pharynx length; c means total body length/tail length; Hd. means head diameter; a. b. d. means anal body diameter; c’ means tail length/a. b. d.; Spic means spicule length as arc; L means total body length; A% means amphid diameter as percentage of corresponding body diameter; R3 means cephalic seta length as percentage of head diameter; Ps means number of precloacal supplements; V% means position of vulva from anterior as percentage of total body length; HD means head diameter as percentage of posterior oesophagus body diameter; LPA means length of posterior region of the stoma in amphid diameters.

3 Species Description

Family COMESOMATIDAE Filipjev, 1918

Subfamily DORYLAIMOPSINAE De Coninck, 1965

GenusVitiello, 1969

sp. nov.

(Figs.1–2, Table 1)

Type Material

Male holotype, slide number QZ20120713L206. Femaleallotype, slide QZ20130103M206. 3 male paratypes, slidesQZ20121012L410, QZ20121012H405, QZ20120713H406; 3 female paratypes, slides QZ20130103 M205, QZ20130 103M403, QZ20130103H205.

Fig.1 Hopperia sinensis sp.nov. a, lateral view of male anterior part; b, lateral view of male tail region and copulatory apparatus; c, lateral view of female tail region; d, lateral view of female anterior part. Scale bar, 20μm.

Fig.2 Hopperia sinensis sp.nov. Male: (a) head region (stoma); (b) head region (amphid); (c, d) copulatory apparatus. Female: (e) total view; (f) lateral differentiation (mid body); (g) mid body part (vulva); (h) head region (cephalic setae). Bar scales: a, b, c, d, f, g, h=10μm; e=100μm.

Table 1 Measurements of Hopperiasinensis sp. nov. (in μm)

Type Locality and Habitat

All the specimens were collected from Luoyang River estuary mangrove forest () in Quan-zhou City. Station QZLY: 24.94˚N, 118.67˚E;4 collected in July, 2012;1–3 in October, 2012.1–4 in January, 2013. Total nitrogen, 1.31mgg−1; Total phosphorus, 0.40mgg−1; Organic carbon, 1.72%; Sulfide, 16.89×10−6mgg−1.

Etymology

The name of the species made reference to the country of origin, China.

Measurements (Given in Table 1)

Allotype ♀1:– 200 V 18222020µm; a=40, b=10, c=10, V%=44% 14 50 51 31

Description

Males. Cylindrical body is attenuated towards the ends. Lips are swollen and set off from the body by a constriction at the level of outer labial setae. Cuticle is marked with fine transverse rows of punctations from the level of amphid to near tail tip. Lateral differentiation appears with larger, more irregularly distributed dots behind 3–5 transverse rows of dots posterior to amphid. These larger dots are mainly on pharyngeal and tail region. In the rest of the body, the lateral punctuations are enlarged, and arranged in nearly regular transverse rows. Somatic short conical setae appear along the borders of lateral field. There are three crowns of anterior sensilla: the six inner labial sensilla papilli form, six short outer labial sensilla of about 2μm long, and four cephalic setae of 2.4–2.8μm long (17%–20% of head diameter). Amphideal fovea spiral are with 2.25–2.5 turns, and at the level of cephalic setae, occupying 53%–61% of corresponding body diameter, with anterior border 5μm from the front end. Anterior portion of the buccal cavity is cup-shaped, while the posterior portion of buccal cavity is cylindrical, strongly cuticularised, 18–21μm deep, and surrounded by pharyngeal muscles. Three sclerotized and equally large pointed teeth are inserted at the junction between the two compartments. The pharynx is long cylindrical and gradually expanded, without forming a true bulb. The cardia is small. Nerve ring is indistinct, and situates anteriorly to excretory pore. Ventral gland cell is behind the cardia. Reproductive system is diorchic, with two testes in tandem with anterior testis on the left and posterior testis on the right of gut. Spicules, proximally cephalate and distally acute, are slightly curved, 41–45μm long along the arc (1.3–1.5 a. b. d.), with broadband velum and a short conspicuous central strip at the proximal end. The gubernaculum, with apparent lateral guiding pieces, are formed by one central tubular piece that is weakly sclerotized with 11–16μm long dorso-caudally directed apophyses. Glandular tissue can be observed surrounding spicula and gubernaculum. There is a small pre-cloacal seta and 13– 14 fine tubular preclocal supplements.The tail is 162–173μm long (c’=4.9–5.7), conico-cylindrical, gradually tapering tilltail tip pointed. Caudal gland is invisible. Some caudal setae are present but there are no terminal seta.

Females. Female is similar to male in general, but with a longer body (1930–2095μm in female versus 1750– 2010μm in male) and tail (200–203μm in female versus 162–173μm in male). Ovaries are opposed and outstretched, with anterior ovary to the left and posterior ovary to the right of the intestine. Vulva is located at 44%–47% of body length.

Differential Diagnosis

sp. nov. from mangroves in Fujian Province, China is characterized by the short cephalic setae (2.4–2.8μm long or 17%–20% h. d.), amphids with 2.25–2.5 turns, stoma depth 18–21μm, 13–14 fine tubular precloacal supplements, and pointed tail tip.

sp. nov. is closely related to theJensen, 1992, sharing the same length of buccal cavity, same number of amphid turns, and a pointed tail tip.is also found in muddy sediment amongst mangroves.sp. nov. differs fromin the following characters: smaller ‘a’ value, longer body size, 13–14 precloacal supplements, a setose third crown cephalic sense (Table 2).

Table 2 Differentiating characters of male Hopperia species

Notes: Reviesed base on Pastor de Ward C. T., 2004. Abbreviations (*: date from picture; –: date absent, +: present, but are very indistinct and cannot be enumerated with certainty.)

Fig.3 Pictorial key to all known valid species of Hopperia.

So far, a total of 14 valid species are described for the genus(Electronic database: http://www.marinespecies.org/aphia.php?p=taxlist). The composite differentiating characters for all malespecies were provided as an aid to identification (Table 2). From this table it is clear thatsp. nov. is very similar to. The main differential characteristic between them is the spicules ofwith conspicuous hook-like projection at the distal end. Four of fourteen species, namelyJensen, 1992,Muthumbi, Soetaert & Vincx, 1997,Leduc, 2012 andsp. nov., have conico- cylindrical tail with pointed tip. Leduc (2012) renewed the dichotomous key of the genus at the base of Pastor de Ward’s (2004). A pictorial key to all known valid species ofis shown in Fig.3.

Acknowledgements

This work was supported by grants from the National Science Foundation of China (No. 41176107), Open Research Fund Program of Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-environment (No. fmfre2014012), and the Training Program of Fujian Excellent Talents in University. We are very grateful to Pastor C. T. de Ward for her help. We also thank the ano- nymous referees for their revision and comments.

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(Edited by Qiu Yantao)

DOI 10.1007/s11802-015-2742-6

ISSN 1672-5182, 2015 14 (6): 1111-1115

© Ocean University of China, Science Press and Spring-Verlag Berlin Heidelberg 2015

(September 11, 2014; revised December 18, 2014; accepted October 19, 2015)

* Corresponding author. 0086-18950189618 E-mail: guoyuqing@jmu.edu.cn