Spinitectus (Paraspinitectus) palmyraensis Gonzalez-Solis & Vidal-Martinez
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publication ID |
https://dx.doi.org/10.3897/zookeys.892.38447 |
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lsid:zoobank.org:pub:8951A3F9-FDD0-4041-8BEA-BDA48C1B616C |
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https://treatment.plazi.org/id/E645F51A-8D4B-58ED-929E-13CB1D81553E |
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scientific name |
Spinitectus (Paraspinitectus) palmyraensis Gonzalez-Solis & Vidal-Martinez |
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sp. nov. |
Spinitectus (Paraspinitectus) palmyraensis Gonzalez-Solis & Vidal-Martinez sp. nov. Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3
Description.
General: medium-sized nematodes with transverse rings of markedly long, posteriorly directed spines. First ring situated at level of base of prostom ( Figs 1C View Figure 1 , 2D View Figure 2 ), other rings extending posteriorly to mid-length of body. Spination is weakly visible in the posterior end of body ( Figs 1H View Figure 1 , 3C, G View Figure 3 ). Rings 1-4 with 11-14 uninterrupted spines, rings 5-12 with 13-17 interrupted spines at lateral side of body, rings 13-14 with 13-15 discontinuous spines in number and shape ( Fig. 1A View Figure 1 ), rings 15 and posteriormost rings with 6 relatively large spines with a pore-like in their bases ( Fig. 3B View Figure 3 ). In some specimens, anteriormost rings incomplete, assymetrical and not forming a circle or with some missing spines ( Fig. 1F, G View Figure 1 ), sometimes with double spines ( Fig. 1E View Figure 1 ). Spines from rings 1-15 not overlapping each other, spines of more posterior rings overlapping ( Fig. 3A View Figure 3 ). Cuticle transversely striated forming elevated rings ( Figs 2 D–E View Figure 2 , 3A View Figure 3 ). The oral aperture oval surrounded by four submedian labia, which form continuous dorsal and ventral margins around the mouth. Two dorsal and two ventral submedian sublabia, curved and attached by their bases to surface of labia. There are two lateral, highly reduced pseudolabia without internal extensions. Two pairs of submedian cephalic papillae are present and a pair of lateral, barely visible amphids are situated outside the oral aperture ( Figs 1B View Figure 1 , 2 A–C View Figure 2 ). Vestibule straight, rather long, with anterior end distinctly distended to form funnel-shaped prostom in lateral view ( Fig. 1A, F View Figure 1 ). Esophagus clearly divided into muscular portion and posterior glandular, much longer and slightly wider portion. Nerve ring encircles muscular esophagus near its anterior end, situated between 8th and 9th rings of cuticular spines ( Fig. 1A, F View Figure 1 ). Excretory pore situated between 9th and 10th rings of spines ( Figs 1A, F View Figure 1 , 2E View Figure 2 ). Small, trifurcated deirids situated just anterior to first ring of spines ( Figs 1A, C, F View Figure 1 , 2F View Figure 2 ). Tail of both sexes conical.
Male (4 specimens, measurements of holotype in parenthesis): length of body 3.90-5.50 (4.92) mm, maximum width 89-115 (103). First cuticular ring 31-33 (33) from anterior extremity, armed with 11-14 (12) spines, 10-14 (12) long. Larger spines 22-23 (22-23) are at the level of the glandular esophagus. Vestibule including prostom 188-213 (188) long; prostom 21-28 (28) long and 7-9 (8) wide. Muscular esophagus 251-278 (261) long; glandular esophagus 0.82-1.55 (0.93) mm long, 32-41 (33) wide; length ratio of both parts of esophagus 1:3.2-4.2 (3.5). Entire esophagus and vestibule represent 28-31 (29)% of whole body length. Nerve ring and excretory pore 212-223 (223) and 233-254 (254), respectively, from anterior extremity. Deirids 30-32 (32) from anterior end of body. Posterior end of body ventrally curved, provided with well-developed caudal alae reaching posteriorly to end of tail ( Figs 1J View Figure 1 , 3 C–F View Figure 3 ). Well-developed longitudinal, ventral cuticular ridges (area rugosa) present in precloacal region, formed by 9 lines in its most anterior part, 10 at middle and 3 near cloacal opening ( Figs 1J View Figure 1 , 3C, E View Figure 3 ). Precloacal papillae: 4 pairs of subventral, pedunculate, close to each other and equally distributed papillae present. Postcloacal papillae: 6 pairs of subventral pedunculate papillae, although second pair slightly laterally displaced. One pair of lateral papillae situated between two last pairs of subventrals (probably representing phasmids) ( Figs 1J View Figure 1 , 3 D–F View Figure 3 ). Spicules dissimilar and unequal; large (left) spicule 673-766 (713) long, striated, with expanded proximal end 31-39 (39) wide, and bifurcated distal part. Small (right) spicule boat-shaped, 126-155 (126) long, with narrowed, ventrally bent distal end and two dorsal protuberances ( Fig. 1I, J View Figure 1 ). Length ratio of spicules 1: 4.4-5.6 (5.6). Tail 123-160 (141) long, with blunt tip ( Fig. 3F View Figure 3 ).
Gravid female (4 specimens; measurements of allotype in parentheses): body length 5.89-7.14 (6.26) mm, maximum width 129-143 (143). First cuticular ring 27-31 (27) from anterior extremity, 11-14 spines 12-15 (12) long. Larger spines 12-14 (12-14) at the level of the glandular esophagus. Vestibule including prostom 183-211 (183) long; prostom 23-28 (28) long and 7-9 (7) wide. Muscular esophagus 273-300 (289) long; glandular esophagus 0.908-1.165 (1.165) mm long, 38-46 (46) wide; length ratio of both parts of esophagus 1: 3.3-4.1 (4). Entire esophagus and vestibule with prostome represents 23-26 (26)% of whole body length. Nerve ring and excretory pore 206-231 (206) and 219-266 (206), respectively, from anterior extremity. Deirids 26-30 (26) from anterior end. Vulva with slightly elevated lips, postequatorial, situated at 4.24-4.82 (4.58) mm from anterior extremity, representing 67-73 (73)% of body length. Vagina muscular, directed posteriorly from vulva ( Fig. 1D View Figure 1 ). Ovaries extending slightly anterior to anus level ( Fig. 1H View Figure 1 ). Eggs in uterus oval, thick-walled (4-5 wide), smooth; larvated eggs 35-42 × 23-27 (34-41 × 25-27) ( Fig. 1D View Figure 1 ). Tail conical, 73-102 (73) long, with lateral phasmids and knob-like appendage at tip, 7-9 long, separated from body by a narrow constriction ( Figs 1H View Figure 1 , 3G, H View Figure 3 ).
Etymology.
The specific name of this nematode relates to the collection locality (Palmyra Atoll).
Type-host.
Albula glossodonta ( Forsskål) ( Albulidae ).
Site of infection.
Intestine.
Type-locality.
Palmyra Atoll, Eastern Indo-Pacific Ocean.
Prevalence and mean intensity.
54.2 and 3.2 ± 4.0 (n = 24).
Specimens deposited.
Holotype and paratype (in SEM stub) specimens in the Helminthological Collection of the Institute of Parasitology, Academy of Sciences of the Czech Republic, Ceske Budejovice (no. N-1073) and CHCM no. 633 (allotype) (1 vial, 1 specimen ♀).
Remarks.
According to Moravec (2007), Moravec and Justine (2009), and Moravec and Klimpel (2009), the genus Spinitectus is one of the 24 valid genera within the family Cystidicolidae . This genus is represented by a large number of species described mainly from freshwater and marine fishes ( Moravec et al. 2002) and includes the monotypic subgenus Paraspinitectus ( Moravec and Justine 2009).
Due to the presence of markedly reduced pseudolabia in the oral opening and a body covered by spinose rings, the nematodes herein described were assigned to the subgenus Paraspinitectus , as diagnosed by Moravec and Justine (2009). The subgenus was created based on the structure of the oral opening of a lone female nematode reported as Spinitectus (Paraspinitectus) sp. collected from A. glossodonta , off New Caledonia. Spinitectus beaveri , a species originally described from Albula vulpes (Linnaeus) ( Albulidae ) in Biscayne Bay, Florida ( Overstreet 1970) and later examined by SEM by Jilek and Crites (1982), had similar structure to the oral opening, and thus became the type species of the subgenus. The former was reported in the same host and geographical region (southern Pacific Ocean), while the latter was described from a congeneric host ( A. vulpes ) and different geographical region (off Florida). They both have very similar morphological characteristics to S. (P.) palmyraensis sp. nov., although, the new species differs from S. (P.) beaveri in the length of right spicule (673-766 vs 390-430 mm), vestibule (188-213 vs 80-90 mm), different pattern in the distribution and number of spinose rings, position of nerve ring (between rings 9-10 vs 3-7), and number of caudal papillae. The new species differs from Spinitectus (P.) sp. in the position of nerve ring (between rings 10-11), excretory pore (rings 9-10 vs 14-15) as well as the distribution pattern of spinose rings.
Interestingly even though the three species within Paraspinitectus occur in closely related hosts, morphological differences are evident among species of Spinitectus parasitizing albulid fishes around the world. Potentially, ecological differences of their hosts or habitats are substantial enough to select for this interspecific variability.
Morphological features as reduced pseudolabia, small triangular sublabia in the oral opening, trifurcated deirids (probably also present in Spinitectus (P.) sp.), and spinose rings with two different patterns of arrangement are common to the three known forms assigned to the subgenus. These characteristics support the validity of the subgenus Paraspinitectus and highlight the need for detailed SEM examination of cystidicolid specimens to determine the substantial intraspecific differences when comparing among species.
Within the Cystidicolidae there is a recently created genus, Ascarophisnema Moravec & Justine, 2010 with remarkable similarities with the new species. Similarities between the Ascarophisnema and Spinitectus include trifurcated deirids (only reported in these two genera), the structure of the oral opening, and the number and distribution of caudal papillae. Although the presence of spinose rings in Spinitectus clearly set it apart from Ascarophisnema . Probably, both genera are closely related but a phylogenetic analysis using molecular and morphological data is needed to clarify this situation.
This is the second nominal species reported within the subgenus Paraspinitectus and represents a new geographical record (southern Pacific region), since the previous report was a generically identified female from the same host species.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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