Camallanidae Railliet and Henry, 1915

Harnoster, Florence, Svitin, Roman & Preez, Louis Du, 2019, Serpinema cayennensis n. sp. (Nematoda: Camallanidae), a parasite of the freshwater turtle Rhinoclemmys punctularia Daudin (Reptilia: Testudines: Geoemydidae) from French Guiana: morphology and phylogenetic relationships with other turtle-parasitising camallanids, Zootaxa 4679 (1), pp. 181-193 : 185-187

Family Camallanidae Railliet and Henry, 1915

Subfamily Camallaninae Yeh, 1957

Genus Serpinema Yeh, 1960

Species: S. cayennensis n. sp.

Type-host: Rhinoclemmys punctularia (Daudin, 1801) (Reptilia: Testudines : Geoemydidae ).

Type-locality: Cayenne, French Guiana; 04°90’14”9 N 52°35’76”7 W; 21m above sea level.

Type-material: Holotype (male, [496]), allotype (female, [497]), paratypes (9 males, 13 females, [498]) deposited in the National Museum Parasite Collection (Bloemfontein, South Africa).

Site in host: Intestine.

Infection parameters: One of three hosts was infected with 25 nematodes

Representative DNA sequences: GenBank [ MN 100746 ] (18S); [ MN 100745 ] (28S); [ MN104841 ] (COI)

ZooBank registration: To comply with the regulations set out in article 8.5 of the amended 2012 version of the International Code of Zoological Nomenclature (ICZN, 2012), details of the new species have been submitted to ZooBank. The Life Science Identifier (LSID) for Serpinema cayennensis n. sp. is urn:lsid:zoobank.org: pub: [5BB3B5D0-B71B-4CE1-AFB9-1A10A63BC0A2]; urn:lsid:zoobank.org:pub:act: [C8057B6B-B80A-41B0- A806-6331B6AB516F].

Etymology: The species is named after the city Cayenne, the type locality of the species.

Remarks. The new species belongs to the genus Serpinema due to the presence of two lateral valves of the buccal capsule, each possessing longitudinal ridges separated into dorsal and ventral groups, without a conspicuous central ridge and parasitism in a freshwater turtle ( Ivashkin et al. 1971).

Hitherto, eight species of the genus Serpinema are considered as valid. Serpinema cayennensis n. sp. can be distinguished from all other species of the genus by two distinctive morphological characters. From three species it can be easily differentiated by the shape of the distal end of the right spicule: S. cayennensis n. sp. bears a short process on the distal end while S. amazonicus Ribiero, 1941 , S. kachugae Baylis and Daubney, 1922 and S. lissemysus Gupta and Singh, 1959 have simply a sharpened end at their right spicules. By the number of caudal papillae, the new species can be differentiated from most of the other species by having six pairs of precloacal papillae, while S. amazonicus , S. intermedius Hsü and Hoeppli, 1931 , S. kachugae , S. magathi Sprehn, 1932 , S. microcephalus Dujardin, 1845 , S octorugatum and S. trispinosus Leidy, 1852 described with seven pairs of precloacal papillae. Only S. lissemysus was described with six pairs of precloacal papillae, although it noticeably differs from S. cayennensis n. sp. in the shape of the right spicule. The new species is also unmistakably different from C. emydidius parasitic in freshwater turtles in southern Brazil by the shape of the right spicule (simple vs complex) and the number of precloacal papillae (six vs seven).

All species of Serpinema were described in the XIX and XX centuries and generally known from their first descriptions. Thus, different authors measured characters in different ways which complicates the efficiency of the morphometrical analysis. Based on the latest descriptions and re-descriptions, we summarised morphometric data ( Table 1 ) of valid Serpinema species in order to provide additional characteristics for the species differentiation. Most of the measurements of S. cayennensis n. sp. are generally similar to those of the other species. However, the new species has the buccal capsule slightly wider and the tridents markedly longer than in all other known species. Also, S. cayennensis n. sp. has an unusual length ratio of the muscular and to glandular oesophagus. Most of the species have the muscular and glandular oesophagus of about the same length. The only two species namely S. magathi and S. octorugatum ( Sharma et al, 2002) were described with notably shorter muscular oesophagus (about 60% and 75% of glandular oesophagus). Serpinema cayennensis n. sp. has muscular oesophagus comprising from 29 to 65 % of the glandular oesophagus length.

Molecular analysis. The only available 28S fragment in GenBank, of the genus Serpinema belongs to S. octorugatum from Thailand. Besides the species of Serpinema , alignments of five species of Camallanus from the Australian freshwater turtles ( C. waelhreow , C. tuckeri , C. sprenti , C. nithoggi and C. beveridgei ) and two Camallanus spp. from African clawed frogs, Xenopus spp. ( C. xenopodis Jackson et Tinsley, 1995 and C. kaapstaadi Southwell et Kirshner, 1937 ) were downloaded from GenBank and included in the phylogenetic analyses based on 28S alignments. In this analysis Procamallanus slomei Southwell et Kirschner, 1937 was used as an outgroup ( Fig. 3 ). The resulting tree showed that the Serpinema cayennensis n. sp. from French Guiana is placed separately to the clade formed by S. octorugatum from Thailand and distantly related to Camallanus spp. from Australian turtles. In that clade S. octorugatum also appears separately to the well-supported sub-clade of Camallanus spp.

Unfortunately, no 18S or COI alignments of any species of Serpinema or turtle-parasitising Camallanus are available in GenBank. Therefore, 18S alignments of only the species parasitisng fish were included in the analysis: Camallanus carangis Olsen, 1954 , C. oxycephalus Ward and Magath, 1916 , C. hypophthalmichthys Dogel and Akherov, 1954 , C. cotti Fujita, 1927 and C. lacustris, Zoeg, 1776 . The newly obtained 18S sequence of Procamallanus slomei was used as an outgroup. The resulting tree ( Fig. 4 ), based on partial 18S alignments, showed distant relationships between Serpinema and a weakly supported clade of fish-parasitising Camallanus spp.

The COI alignments of only four species of Camallanus were downloaded from GenBank: fish parasitising C. cotti and C. hypophthalmichthys and C. kaapstaadi and C. xenopodis from African clawed frogs. Alignment of P. slomei was also used as outgroup. The tree based on COI alignments ( Fig. 5 ) also showed distant relationships between S. cayennensis n. sp. and selected species of Camallanus .

Figures

FIGURE3. Phylogenetic tree of two species of Serpinema and seven species of Camallanus based on Bayesian Inference analysis of partial 28S rDNA sequences.

FIGURE4. Phylogenetic tree of Serpinema cayennensis n. sp. and four species of Camallanus based on Bayesian Inference analysis of partial 18S rDNA sequences.

FIGURE5. Phylogenetic tree of two species of Serpinema cayennensis n. sp. and four species of Camallanus based on Bayesian Inference analysis of partial cytochrome oxidase subunit I (COI) sequences.