INTRODUCTION
During an ecological and taxonomic study of the meiobenthos of Patagonia bays (Chubut and Santa Cruz, Argentina) new free-living marine nematodes were found. This is the third paper of the series. From these areas we describe two new species of the family Leptolaimidae Örley, Reference Örley1880 for these two areas, belonging to the genera: Antomicron Cobb, Reference Cobb1920 and Leptolaimus de Man, Reference de Man1876.
Antomicron Cobb, Reference Cobb1920 has 5 valid species and was reviewed by Vitiello (Reference Vitiello1971), Gerlach & Riemann (Reference Gerlach and Riemann1973) and Platt & Warwick (Reference Platt, Warwick, Kermanck and Barnes1988). Antomicron donsi Allgén, Reference Allgén1946 is described only from females, so we do not include it as a valid species. No previous key has been given.
Leptolaimus de Man, Reference de Man1876 has 40 valid species. It has been reviewed by Gerlach & Riemann (Reference Gerlach and Riemann1973), de Bovée (Reference de Bovée1974), Alekseev & Rassadnikova (Reference Alekseev and Rassadnikova1977) and Platt & Warwick (Reference Platt, Warwick, Kermanck and Barnes1988). De Bovée (Reference de Bovée1974) recognized 30 species and Alekseev & Rassadnikova (Reference Alekseev and Rassadnikova1977) recognized 27 species and 3 subgenera. Several species had been described as females only and they could not be included in keys. A comparison of measurements of the 40 valid species (known with males) to help the future revision of the genera has been added.
Leptolaimus sebastiani Pastor de Ward (Reference Pastor de Ward1984) was the first Leptolaimus species described from the coast of Patagonia Argentina and Leptolaimus vinnulus Vitiello, Reference Vitiello1974 was the first known Leptolaimus species recorded from the same coast (Pastor de Ward, Reference Pastor de Ward1984).
The genus Procamacolaimus Gerlach, Reference Gerlach1954 includes nine species of marine camacolaimid nematodes: Procamacolaimus dorylaimus Holovachov, Reference Holovachov2003 was the first known Procamacolaimus species recorded from the coast of Patagonia Argentina.
MATERIALS AND METHODS
Description of sites studied
Samples were collected from Patagonia littoral coastal sediments at Puerto Madryn, Chubut Province (42°45′S 64°55′W) and at Puerto San Julián, Santa Cruz Province (49°13′S 67°40′W), Argentina (see Figure 1). Puerto Madryn bay is located in Golfo Nuevo, Patagonia. Tidal currents are the most important water movement with a range of 4 m between high and low tides. The specimens from Puerto Madryn beach were collected in front of the city, on upper littoral at medium sand, 1 m depth. Specimens from the Golfito locality came from near sublittoral, 5 m depth.
Fig. 1. Patagonian map showing the samples stations: (A) Golfito in Puerto Madryn Bay (Chubut); (B) El Rincón in San Julián Bay (Santa Cruz).
The San Julián bay is 19.9 km long and has two distinct areas with one near the entrance to the bay (length/width 6.8/5.3 km) and one towards the very end (length/width 11.8/8.2 km) separated by a narrow passage where the city of Puerto San Julián is located. Tidal currents are the most important water movement with a range of 8 m. The specimens were collected in ‘El Rincón’ at the end of the bay, in low littoral, at very fine sand substrate.
Sample collection and treatment
On each site, five sediment samples were taken with a cylindrical Plexiglas corer, 10 cm high and 2.8 cm in diameter. They were preserved in 5% formaldehyde in filtered seawater, sieved through both 500 µm and 50 µm mesh sieves. The nematodes present on the 50 µm sieve were separated by Ludox™ and then counted and identified to species level. Nematodes were fixed following the method described by Ditlevsen (Reference Ditlevsen1911) and preserved in anhydrous glycerin on slides sealed with Canada resin.
Specimen analysis
Morphometric data were obtained from camera lucida drawings using a Zeiss microscope with differential interference contrast (DIC). The measurements are in microns. Photographs were taken with Olympus microscopy equipment with DIC. Sediment analyses were carried out by dry-sieving and classified according to the Wentworth scale. Literature has been obtained from Deprez (Reference Deprez2006). Type specimens were deposited in the Museo Nacional de Ciencias Naturales ‘Bernardino Rivadavia’, Argentina. The classification followed for the systematic position of the species was De Ley & Blaxter (Reference de Ley and Blaxter2002). De Man's ratios, a, b and c used in this paper were calculated as standard.
Abbreviations
Abd, anal body diameter; aw, width; bdc, body diameter at level of cephalic setae; bda, body diameter at amphidial fovea level; bdph, body diameter at level of pharyngeal end; daa, distance from anterior end to anus; daph, oesophagus length; dav, distance from anterior end to vulva; mbd, maximum body diameter; lcs, length of cephalic setae; spic, spicular length in microns, along the arc; spic%, spicule chord as proportion of anal body diameter; c’, tail in anal diameter; gub, gubernaculum length; gub%, gubernaculum length as proportion of cloacal body diameter; L, total length; V%, distance from the anterior end to the vulva opening in percentage of total length; amph%, amphidial fovea diameter as percentage of corresponding body diameter; T, tail length; PS, precloacal supplements. Measurements are in µm apart from body length which is in mm.
RESULTS AND DISCUSSION
Fig. 2. Antomicron alveolatum sp. nov. (A) Oesophageal region of male holotype; (B) posterior end of male paratype; (C) head region of male holotype; (D) copulatory apparatus and precloacal supplements of male holotype.
Plate 1. Antomicron alveolatum sp. nov. (A) Amphidial fovea on anterior end of male holotype; (B) cephalic setae of male holotype; (C) alveoli on oesophageal region of male holotype; (D) lateral band of male holotype; (E) copulatory apparatus, precloacal supplements, spicule and gubernaculum of male holotype; (F) tail of male holotype; (G) entire male holotype. Scale bars: A, B, C, D, E & F= 10 µm; G = 20 µm.
TYPE MATERIAL
Holotype: male. Registration number MACN-In 37989; coordinates: 49°20′96″S 67°42′08″W; water depth: low littoral. Collected by C.T. Pastor de Ward, 23 January 2008.
Table 1. Measurements (µm) of Antomicron alveolatum sp. nov.
Paratype: male. Registration number CNP NEM 1533; coordinates: 49°20′96″S 67°42′08″W; water depth: low littoral. Collected by C.T. Pastor de Ward, 23 January 2008.
ETYMOLOGY
From Latin word alveolatum (adj.) = alveolate, with presence of alveoli.
MATERIAL EXAMINED
Measurements: see Table 1.
DESCRIPTION
Male (holotype): body length medium-sized. Cuticle with widely spaced transverse striation 2 µm apart from smooth lateral field, 2 µm wide. With lateral differentiation unstriated 2 µm in diameter. No labial sensillae were observed. There are four 5 µm long cephalic setae. There is a longitudinal row of papillae down both sides of the lateral line. Amphidial fovea oval, 15 µm long and 5 µm wide, located 5 µm from anterior end on head capsule. Buccal cavity is thin, 17 µm long. Oesophagus is widening towards the posterior end cardia 150 µm long. Excretory pore is 110 µm from anterior end. Along oesophageal region and posterior to excretory pore 35 alveoli observed. Male with one testis right to the intestine (Figure 5). Spicules equal length, 26 µm long measured along blade, slightly curved ventrally. Gubernaculum curved anteriorly with a dorsal apophysis 18 µm long. Three 10 µm long cuticularized tubular precloacal supplements, the posterior most located 15 µm from spicule head, the second one located 30 µm and the third one located 52 µm. Tail 113 µm long, distal third cylindrical in shape. On the tail are two subventral pairs of setae.
DIAGNOSIS AND RELATIONSHIPS
Antomicron alveolatum sp. nov. is characterized by having alveoli along posterior oesophageal region and anterior intestine and three precloacal supplements in male. Antomicron alveolatum sp. nov. resemble A. profundum Vitiello, Reference Vitiello1971 and A. intermedius Gagarin & Thanh, Reference Gagarin and Thanh2005 by the presence of alveoli but in these species their position is posterior to the oesophageal region and it also differs in number of precloacal supplements. The new species also resemble A. pellucidum Cobb, Reference Cobb1920, A. elegans Lorenzen, Reference Lorenzen1969 and A. pratensis Lorenzen, Reference Lorenzen1969 by the presence of precloacal supplements but differs in that they do not have alveoli along the posterior oesophageal region.
KEY FOR THE SPECIES OF GENUS ANTOMICRON
1. With alveoli or cuticularized papillae in oesophageal region… … … … … … … … … … … … … … … . 2
— Without alveoli or cuticularized papillae in oesophageal region… … … … … … … … … … 3
2. With alveoli on oesophageal region; Patagonia, Argentina… … … … … … … … A. alveolatum sp. nov.
— With alveoli posterior to oesophageal region; Mediterranean… … … .A. profundum Vitiello, Reference Vitiello1971
3. Amphidial fovea posterior to cephalic capsule; Costa Rica … … … … … … … … . A. pellucidum Cobb, Reference Cobb1920
— Amphidial fovea for at least 50% on cephalic capsule… … … … … … … … … … … … … . .4
4. Gubernaculum with dorsal apophyses … … … … … . . 5
— Gubernaculum without dorsal apophyses; North Sea… … … … … … …A. pratensis Lorenzen, Reference Lorenzen1969
5. Elongated amphidial fovea, length/width= 0.5; North Sea… … … … … … … … . . A. elegans Lorenzen, Reference Lorenzen1969
— Rounded amphidial fovea, length/width = 1; Cam River, Vietnam … … … … … … … … … … … … … … … A. intermedius Gagarin & Thanh, Reference Gagarin and Thanh2005
Fig. 3. Leptolaimus (T) gabinoi sp. nov. (A) Oesophageal region of male holotype; (B) copulatory apparatus and precloacal supplements of male holotype; (C) oesophageal region of female paratype; (D) posterior end of female paratype; (E) posterior end of male paratype.
Plate 2. Leptolaimus (T) gabinoi sp. nov. (A) Entire female paratype; (B) entire male holotype; (C) copulatoy apparatus and precloacal supplements of male holotype; (D) cephalic setae and amphidial fovea on anterior end of male holotype; (E) buccal cavity of male holotype; (F) vulva; (G) cephalic setae on anterior end of female paratype; (H) buccal cavity of female paratype. Scale bars: A & B= 50 µm; C, D, E, F, G & H= 10 µm.
Table 2. Measurements (µm) of Leptolaimus (T) gabinoi sp. nov. (range, mean value in parentheses).
TYPE MATERIAL
Holotype: male. Registration number MACN-In 37992; coordinates: 49°20′96″S 67°42′08″W; water depth: low littoral. Collected by C.T. Pastor de Ward, 23 January 2008.
Paratype: female. Registration number MACN-In 37993; coordinates: 49°20′96″S 67°42′08″W; water depth: low littoral. Collected by C.T. Pastor de Ward, 23 January 2008.
Two males and one female additional specimens. Registration number CNP NEM 1534-1536; coordinates: 49°20′96″S 67°42′08″W; water depth: low littoral. Collected by C.T. Pastor de Ward, 23 January 2008.
ETYMOLOGY
Dedicated to G.M. Ward in recognition of his help given during the sampling for this project.
MATERIAL EXAMINED
Measurements: see Table 2.
DESCRIPTION
Male (holotype): body length medium-sized. Cuticle striated 1.2 µm. With lateral differentiation 2 µm in diameter. Four long cephalic setae 6 µm long. There is a longitudinal row of long cervical setae down each side of the lateral field. Amphidial fovea is circular, 4 µm in diameter, 10 µm from anterior end. Buccal cavity is small, 10 µm long. Oesophagus with a small terminal bulb and a short cardia.
Male with one testes right to the intestine (Figure 5). Spicules equal length, 20 µm long, measured as a curve, slightly curved ventrally. Gubernaculum with dorsal apophysis, 13 µm long. Three, 17 µm long cuticularized tubular precloacal supplements cephalate proximally and terminating distally in several hooks, sourrounded by an oval disc 8 µm in diameter. Tail is 86 µm, conical in shape with posterior swelling. On the tail are three subventral pairs of setae, two small alveoli and one subdorsal setae.
Female (paratype): females are similar to males in general body shape with two antidromously reflexed ovaries right/left to the intestine (Figure 5). Vulva is 51.4% of body length. Spermatheca is globular, short vagina. Tail 100 µm long, conico-cylindrical in shape. Caudal glands present.
DIAGNOSIS AND RELATIONSHIPS
Leptolaimus (T) gabinoi sp. nov. is characterized by the number of precloacal supplements (three) with hamate distal end. It belongs to the group of Leptolaimus (Tubulaimus) having hamate appendages, together with L. macer Lorenzen, Reference Lorenzen1972 and L. scotlandicus Jayasree & Warwick, Reference Jayasree and Warwick1977. Leptolaimus (T) gabinoi sp. nov. resembles: Leptolaimus asiaticus Gagarin & Thanh, Reference Gagarin and Thanh2005 by the number of precloacal supplements (three) but differs by the shape of amphidial fovea which is long and thin; L. kerguelensis de Bovée, Reference de Bovée1977 and L. leptaleus Lorenzen, 1921 by the number of precloacal supplements (three) but differs in the length of the spicule, the value of a, b and c; L. puccinealliae Lorenzen, Reference Lorenzen1969, L. pocillus de Bovée, Reference de Bovée1974, L. tritubulatus Boucher & Helléouët, Reference Boucher and Helléouët1977, L. venustus Lorenzen, Reference Lorenzen1972 and L. vinnulus Vitiello, Reference Vitiello1974 by the number of precloacal supplements (three) but differs in the length of the spicule, the value of a and c. Leptolaimus (T) gabinoi sp. nov. differs from: L. minutus Vitiello, Reference Vitiello1971 and L. pumicus Vitiello, Reference Vitiello1970 by the presence of precloacal supplements which are absent in these two species; L. acicula Lorenzen, Reference Lorenzen1966, L. alatus Vitiello, Reference Vitiello1977, L. ampullaceus Warwick, Reference Warwick1970, L. antarticus Cobb Reference Cobb1914, L. cupulatus Lorenzen, Reference Lorenzen1972, L. danicus Jensen, Reference Jensen1978, L. ditlevseni Kreis, Reference Kreis1963, L. elegans Lorenzen, Reference Lorenzen1972, L. fluvialis Alekseev, Reference Alekseev1981, L. gerlachi Murphy, Reference Murphy1966, L. limicolus Lorenzen, Reference Lorenzen1966, L. longispiculis Alekseev & Rassadnikova, Reference Alekseev and Rassadnikova1977, L. luridus Timm, Reference Timm1963, L. maximus Chitwood, Reference Chitwood1936, L. membranatus Wieser, Reference Wieser1951, L. meyer-reili Jensen, Reference Jensen1991, L. mixtus Lorenzen, Reference Lorenzen1972, L. nobilis Gerlach, Reference Gerlach1956, L. papilliger de Man, Reference de Man1922, L. praeclarus Timm, Reference Timm1961, L. pumilus Gagarin & Thanh, Reference Gagarin and Thanh2009, L. relictus Tsalolikin, Reference Tsalolikin1979, L. sebastiani Pastor, 1984, L. septempapilatus Platt, Reference Platt1973, L. setiger Gerlach, Reference Gerlach1953, L. timmi Vitiello, Reference Vitiello1971 and L. vipriensis Gagarin & Thanh, Reference Gagarin and Thanh2005 by the different number of precloacal supplements; L. surdus Gerlach, Reference Gerlach1954 in the length of the body, the value of a and c (the number of precloacal supplements and the length of the spicule are not comparable because such values are not present in the original work).
A comparison of measurements of the 40 valid species (known from males) of Leptolaimus until now, are pointed out in Table 4.
The species L. longiseta, Allgén Reference Allgén1934; L. norvegicus Allgén, Reference Allgén1936; L. plectoides Chitwood, Reference Chitwood1951; L. steineri Filipjev, Reference Filipjev1922; L. tenuis Gerlach, Reference Gerlach1956; L. trichodes Kreis, Reference Kreis1929 and L. exile Cobb, Reference Cobb1920 are known only from females, so they were not included in Table 4. Leptolaimus longisetosus Allgén, Reference Allgén1928 and L. pellucidus Southern, Reference Southern1914 were transferred to Halaphanolaimus by having circular amphidial fovea and L. haploopis Jensen, Reference Jensen1978 was transferred to Leptolaimoides by their very elongated amphidial fovea (Deprez, Reference Deprez2006).
Fig. 4. Procamacolaimus dorylaimus. (A) Head region of male; (B) anterior end of male, showing buccal cavity; (C) posterior end of male; (D) anterior end of male; (E) head region of female; (F) tail of female; (G) neck region of female; (H) copulatory apparatus and precloacal supplements of male; (I) oesophageal region of male; (J) caudal setae on tail of male. Scale bars: C, F, G & I= 100 µm; A, B, D, E, H & J= 20 µm.
Fig. 5. Reproductive system of: (A) Procamacolaimus dorylaimus female; (B) Leptolaimus (T) gabinoi female paratype; (C) L. (T) gabinoi male holotype; (D) Antomicron alveolatum male holotype; (E) P. dorylaimus male. Scale bars: A & E = 50 µm; B, C & D =20 µm.
Plate 3. Procamacolaimus dorylaimus. (A) Entire male; (B) amphidial fovea on anterior end of male; (C) cephalic setae of male; (D) entire female; (E) buccal cavity of female; (F) vulva; (G) buccal cavity of male; (H) precloacal supplements of male; (I) oesophageal bulb of male; (J) copulatory apparatus of male; (K) cephalic setae of female; (L) tail of male; (M) tail of female. Scale bars: A & D= 160 µm; B, C, E, F, G, H, I, J, K, L & M= 10 µm.
Table 3. Measurements (µm) of Procamacolaimus dorylaimus. (range, mean value in parentheses).
Table 4. Differentiating data of holotype male of Leptolaimus species.
Hd, head diameter.
TYPE MATERIAL
Male: Registration number CNP NEM 1537; coordinates: 42°77′67″S 64°98′83″W, water depth: sublittoral, 5 m. Collected by C.T. Pastor de Ward, 10 December 1986.
Five male and three female additional specimens. Registration number CNP NEM 1538-1545; coordinates: 42°46′56.9″S 65°00′50.7″W; water depth: upper littoral. Collected by G. de Luca, 10 January 1993.
MATERIAL EXAMINED
Measurements: see Table 3.
DESCRIPTION
Male: body length large-sized. Cuticle with fine transverse striation, 2 µm without lateral differentiation. There are four cephalic setae. Six external labial papillae have been observed. Oesophagus with a small terminal bulb and a short cardia. Ventral gland not observed. Spicules equal length, arcuate ventral and strongly ventrally inclined. Gubernaculum with dorsal apophysis. Nine to ten 28 µm long cuticularized tubular precloacal supplements and terminating distally in two hooks, the posteriormost located 52 (average) µm from the cloacal opening. One prominent papilla and several small tubes associated with glands have been observed, along the 28 (average) µm before cloacal opening. Tail is robust, cylindro-conical in shape. On the male tail seven subventral precloacal pairs of setae and one postcloacal papilla.
Female: females similar to males in general body shape, cuticle and arrangement and size of anterior sensilla. Vulva is 48% (average) of body length. Tail is cylindro-conical in shape.
DISCUSSION
The specimens found resemble the original description of P. dorylaimus Holovachov, Reference Holovachov2003 in: the general shape of the body, length of cephalic setae in male and female 5 µm (average) versus 5.5 µm holotype and paratype female, ocelli absent, shape, width and position of the amphidial fovea which is located anteriorly to cephalic setae bases, the de Man's ratio male b = 7 (average) versus b= 8.5 holotype, in female b= 7 (average) versus b= 8.3 paratype female, the de Man's ratio c = 19 (average) in male versus c = 18.6 holotype, in female c= 22 (average) versus c= 20 paratype female, shape of the spicule, gubernaculum and precloacal supplements, position of the vulva 48% (average) length of body versus 44.4% paratype female, distance precloacal papillae–cloaca in males 28 µm (average) versus 20 µm holotype, distance posteriormost precloacal supplement–cloaca in males 52 µm (average) versus 53 µm holotype, stoma strongly cutilarized in male 30 µm (average) long versus 41 µm holotype, length of stoma/cephalic diameter = 1 (average) in male versus 1.5 holotype, length of spicule/length of gubernaculum =3 (average) in male and holotype, length of gubernaculum/length of precloacal supplements =1 (average) in male and holotype.
It also differs in: the de Man's ratio male a= 44 (average) versus a= 60.8 holotype, in female a = 48 (average) versus a = 64.2 paratype female, shorter body length male 1722 µm (average) versus 3374 µm holotype, in female 1433 µm (average) versus 3496 µm paratype female, shorter length of spicule in male 71 µm (average) versus 85.5 µm holotype, shorter length of gubernaculum in male 25 µm (average) versus 33 µm holotype, different number of precloacal supplements in males 9–10 versus 12 holotype, different number of caudal setae in male 14 versus 23 holotype, but the arrangement of the setae in the tail is similar to that species.
Due to similarities in metric and proportional morphological measurements between holotype and our specimens, we consider these individuals as P. dorylaimus.
The observed differences in the measurements (body length, spicule and gubernaculum) may be due to different environmental conditions in the two geographical locations.
