Taxonomic description
Class Ostracoda Latreille, 1802
Subclass Myodocopa Sars, 1866
Order Myodocopida Sars, 1866
Suborder Myodocopina Sars, 1866
Family Phylomedidae Müller, 1906
Subfamily Pseudophilomedinae Kornicker, 1967
Genus Harbansus Kornicker, 1978
Harbansus ningalooi n. sp. (Figs. 1, 2, 3, 4, 5)
Type material
Holotype (Female), dissected on one slide, valves on SEM stub (WAM C57053); 2 paratypes (subadult females) kept in 70 % ethyl alcohol (WAM C57054).
Type locality
Western Australia, Ningaloo Reef, AU VI, 1489, ARMS-1, 17/05/2010, rock, d = 13 m, CReef, 22°46′8.832″S 113°42′16.488″E.
Diagnosis
Surface with shallow pits, two dorsal and two ventral longitudinal ridges, one anterior and one posterior. Beside large shallow pith, smaller pores also present. Shell elliptical with prominent pointed caudal process. Clear bulge present antero-ventrally. Antero-ventral infold striate. Posterior infold with several thick setae and claw-like extensions.
Description of adult female
Carapace sub-rectangular with prominent rostrum, and projecting (relatively pointed) caudal process. Dorsal margin almost evenly rounded, with the greatest high before middle L, and gently sloping towards posterior end. Ventral margin rounded (Figs. 1a, 2a). Surface of carapace with four longitudinal ridges: two running dorsally and two ventrally. Two vertical ridges also present: one running posteriorly, other anteriorly; vertical ridges connecting horizontal ones. Surface covered with large, shallow pits (Fig. 1c, d), in between which numerous small pores also present (Fig. 1d, e). Some surface setae branched and long (Fig. 1b), some short and not branched. Two clear rounded bulging structures present: one situated antero-ventrally (Fig. 2b), other on rostrum (Fig. 2c). These bulging structures best observed from the inside, lateral view (Fig. 1a). Selvage very narrow all around carapace (Fig. 2e). Rostral infold with five setae (Fig. 2c), antero-ventral infold with seven ribs (striation). Posterior infold with six short and broad papappose setae situated dorsally (Fig. 2f, h), and eight claw-like structures: dorsal most and ventral most claws being largest, and ventral most additionally forked distally (Fig. 2d, g). Several short setae also present along posterior and ventral infold (Fig. 2i). Carapace 1.4 mm long.
A1 (Fig. 3b, c). First segment bare. Second segment with one serrulate dorsal seta situated bellow middle L of segment and exceeding distal margin of the following segment. Third segment short and with one ventral annulated, bare seta; and two dorsal bare setae; none of these setae exceeds distal end of the fourth segment. Fourth segment with one dorsal, bare and annulated seta exceeding distal end of the seventh segment. Same segment with two ventral annulated bare setae, one longer than other. Ventral seta of the fifth segment with two distal marginal filaments. Sixth segment fused with the fifth and with very short medial bare seta. Seventh segment with a-seta much longer than seta on the sixth segment; c-seta with one long filament; b- and d-setae subequally long and about same L as seta on the fifth segment. Eight segment with setae g- and e- (g-seta bare, e-seta with one filament) almost subequally long, f-seta with two filaments. One very short additional seta present (most probably) on the eight segment.
Lateral eyes absent, medial eye (Fig. 3c) present and pigmented, with about 10 ommatidia. Bellonci organ with five septae, distally with very small tip.
A2 (Fig. 4a). Protopod without any seta. Endopod 3-segmented: first segment basally with two short setae, second segment with one long sub-distal seta, and third segment with pointed tip but without any seta. Exopod 9-segmented. First segment bare; segments from 2 to 8 with one strong, seta with thick spines proximally and thin setulae distally. Ninth segment with two seta, one long, but almost bare seta (except for thin setulae distally), and one shorter bare seta.
Md (Fig. 3a). Coxa endite spinous with distal tip strongly sclerified. Basis with three subequally long, bare and annulated dorsal setae. Ventrally basis with proximal group of three small bare setae, followed by two serrulate longer setae, in between which another small and bare seta situated; one additional longer, bare annulated seta present on the distal margin; this seta longer than any other ventral setae. Exopod 1-segmented and segment not reaching distal margin of the first endopodal segment. Exopod distally with two thin, bare setae, one two times longer than the other. First endopodal segment with three setae ventro-distally: two long, serrulate and annulated setae exceeding distal end of the following segment, and one very short and bare seta. Second segment of endopod dorsally with a total of seven setae, some short, some long, but all bare and annulated; same segment medio-ventrally with two setae: one serrulate, other bare and with rounded tip; two more spine-like setae present ventro-distally. Terminal segment with two strong (but finely serrated) claws and three fine, bare setae, all with rounded tips.
Mxl (Fig. 5a). Precoxa with five spine-like setae, each with long and stiff setulae. Coxa with one dorsal serrulate seta and two endites with five and six claw-like setae, some serrulate, some plumose. Basis with one annulated, bare dorsal seta and one bare, long ventral seta. Exopod with two setae: longer one bare, shorter serrulate. Endopod first segment with dorsal seta carrying few setulae. Total of 12 setae and/or claws present distally, some belonging to the first and some to the second segment. Exact position of each seta very hard to observe.
L5 (Fig. 5b–d). Basis endite one with bluntly serrated teeth, two medial pappose setae and one short pappose setae distally. Basis endite two consisting of a large tooth with medial spine-like extension. Three coxal endites hard to distinguish between each other, but third one carrying six setae. Exopod with two setae, endopod with two endites: one with seven setae, followed by one claw, and other with six setae.
L6 (Fig. 4b). With one short epipodite seta. First endite with three short and smooth setae; second with two pappose, annulated setae; third endite with six pappose annulated setae; fourth with four pappose annulated setae; end segment with three distal annulated pappose setae and one longer seta (also pappose and annulated).
L7 (Fig. 3d). Two setae in proximal group, one on each side and six setae in distal group (three on each side). Six curved teeth present on the comb, and three on the peg side.
UL (Fig. 4c, d). Each lamella with six claws followed by small posterior extension. Claws 1, 2, and 4 primary; claw 3, 5, and 6 secondary. Only the first claw with strong teeth on posterior margin, other claws with weaker teeth, and secondary claws with very fine serration.
Males: Not known.
Etymology: The species is named after the type locality.
Remarks and affinities
Harbansus ningalooi stands apart from other congeners by the presence of peculiar teeth-like structures on the posterior infold and only one (instead of two) long seta on the posterior extension of the L6. It belongs to the group of species with longitudinal ridges on the carapace, together with H. bradmyersi Kornicker, 1978; H. ferox Kornicker, 1992; H. flax Kornicker, 1998; H. magnus Kornicker, 1984; H. paucichelatus, H. slatteryi Kornicker, 1983; H. thrix Kornicker, 1992; H. vatrax Kornicker, 1995; H. vix Kornicker, 1991; and H. vortex Kornicker, 1995. Harbansus ningalooi is morphologically most similar to H. slatteryi, described from the Lizard Island, Queensland (Kornicker 1983). The two species have a very similar shape and ornamentation of carapace, and they both have two long claws on the terminal segment of the Md endopod. The new species and H. magnus are the only two in this group that have seven dorsal bristles on the second endopodal segment of Md. However, H. magnus is the largest species in the genus (more than 2 mm long) and has more than six claws on the UL. All other species clearly differ from H. ningalooi by the carapace shape, chaetotaxy of the Md, and other details of their morphology.
The adult females of the new species have swimming bristles on the A2 exopod which, according to Kornicker (1978), means that they are swimmers, not crawlers. We have not found males, and the presence of the lateral eyes in this sex is therefore not certain. As for the females, it seems that they only have the medial eye.
Harbansus paucichelatus (Kornicker, 1958) (Figs. 6, 7, 8, 9).
Synonymy
Philomedes paucichelata new species—Kornicker, 1958: p. 233, Figs. 46, 4A–B, 54, A–E, 55, A–C, 87, B, E, H.
Harbansus paucichelatus Kornicker, 1958 n. comb.—Kornicker, 1978: p. 16, Figs. 5, 6, 7, 8, 9, plates 1, 2.
Harbansus paucichelatus Kornicker, 1958—Kornicker, 1984: p. 59, Figs. 32–37; Kornicker et al., 2002: p. 35, Figs. 23–31; Kornicker et al. 2007b: p. 87.
Material examined
-
1.
Three female dissected on three slides and one male dissected on one from: Mexico, Yucatan Peninsula, Between Chabihau and Santa Clara, 21°22′4.33″N, 89°04′13.66″W, 08/05/2005, d = 1.4 m, transparence (water) = 0.9 m, T (water) = 29.8 °C, salinity = 41, pH = 7.96, Dissolved oxygen = 7.59 mg L−1, organic matter = 1.15 %, grain size (sediment) = 1.6 Ø. One female mounted on SEM stub from: Mexico, Yucatan Peninsula, Between Chabihau and Santa Clara, 21°22′06.28″N, 89°04′14.59″W, 08/05/2005, d = 1.1 m, transparence (water) = 0.7 m, T (water) = 21.8 °C, salinity = 30, pH = 7.74, dissolved oxygen = 5.8 mg L−1, organic matter = 0.46 %, grain size (sediment) = 1.2 Ø. 47. Specimens are kept in alcohol (CYMX-1601).
-
2.
One male dissected on one slide, shell on micropaleontological slide and one antenna and antennula used for DNA extraction (WAM C57055), soft parts of one male and two females used for DNA extraction, their shell kept on micropaleontological slides (in the first author collection) from: Mexico, Yucatan Peninsula, Between Progreso and Telchac, 21°17′66″N, 89°36′34″W, 29/11/2013.
Diagnosis
Surface with deep ridges: two dorsal and two ventral longitudinal, one anterior, and one posterior ridge. Beside large pits, smaller pores also present. Shell sub rectangular, with prominent, pointed caudal process. Posterior infold with several thick setae.
Description of adult female
Carapace sub-rectangular with prominent rostrum and relatively pointed caudal process. Dorsal margin almost evenly rounded, with greatest high around middle L, and gently sloping towards posterior and anterior ends. Ventral margin rounded (Figs. 6a, 7a, 8a). Surface of carapace with four longitudinal ridges: two running dorsally and two ventrally. Two vertical ridges also present one running posteriorly, other anteriorly; vertical ridges connecting horizontal ones. Surface covered with large, deep pits (Fig. 6b), in between which numerous small pores also present, as well as around rims of large pits. Inside these pits peculiar structure consisting of nodules connected with radial networks of small, linearly distributed small dots (Fig. 6c, d, f). Some surface setae not branched (Fig. 6e). Selvage relatively narrow all around carapace (Fig. 7a–c) and with fringe of setulae. Rostral infold with five setae, rostrum also marginally serrated. Posterior infold with five short and broad pappose setae situated dorsally (Fig. 7b). Carapace approximately 0.8 mm long.
A1 (Fig. 8b). First segment bare. Second segment with one serrulate dorsal seta situated below middle L of segment and not reaching distal margin of same segment. Third segment short and with one ventral annulated, bare seta; and two dorsal bare setae; none of these setae exceeds distal end of fourth segment. Fourth segment with one dorsal, bare and annulated seta exceeding distal end of fifth segment. Same segment with two ventral annulated bare setae, one longer than other. Ventral seta of fifth segment with one distal marginal filament. Sixth segment fused with fifth and with bare seta. Seventh segment with a-seta much shorter than seta on sixth segment. b- and d-seta subequally long and without filaments; c-seta three filaments; e-seta bare, g-seta slightly shorter and with one filament, f-seta with one filament. Lateral eyes absent, medial eye small and pigmented.
A2 (Fig. 8e). Protopod without any seta. Endopod 2-segmented: first segment basally with two short setae, second segment with one long sub-distal seta, this segment with rounded tip. Exopod 9-segmented. First segment bare; segments from 2 to 8 with one strong seta with thick spines proximally and thin setulae distally. Ninth segment with two seta, one long, and similar to other setae, and one shorter bare seta.
Md (Figs. 7e, 8d). Basis with three subequally long, bare and annulated dorsal setae. Ventrally basis with two short pappose setae. Exopod 1-segmented and segment not reaching distal margin of first endopodal segment. Exopod distally with two thin, bare setae, one about five times longer than the other. First endopodal segment with three setae ventro-distally: one long, pappose and annulated setae exceeding distal end of following segment, and two short and bare seta. Second segment of endopod dorsally with total of four setae; same segment ventro-distally with four short bare setae. Terminal segment with three claws and three fine, bare setae.
L6 (Fig. 9b). First endite with three setae: two short pappose and one longer seta; second with three pappose, annulated setae; third endite with five pappose annulated setae; fourth with five pappose annulated setae, end segment with three distal annulated pappose setae and three longer seta (also pappose and annulated).
L7 (Fig. 9a). Two setae in proximal group, one on each side and four setae in distal group (two on each side). Three curved teeth present on the comb, and three on the peg side. Each seta with four bells at the tip.
UL (Figs. 7f, 8c). Each lamella with six claws followed. Claws 1, 2, and 4 primary; claw 3, 5, and 6 secondary. All primarily claws strongly serrated.
Description of adult male
A1 (Fig. 9f). Second segment with one pappose dorsal seta. Third segment short with two pappose dorsal setae, no ventral setae. Fourth segment with one dorsal seta, no ventral setae. Fifth segment wedged ventrally between the fourth and the sixth segments; sensory seta with bulbous proximal part with abundant filaments, and stem with three filaments near middle and two spines at tip. Sixth segment medial seta with short. Seventh segment: a-seta same L as seta on the sixth segment; b-seta one-third longer than a-bristle, with 2 distal filaments; c-seta longer than sensory seta on the fifth segment. Eight segment: d- and e-setae shorter than c-bristle, bare with blunt tips, f-seta as long c-seta, with marginal filaments; g-bristle shorter than c-bristle. Both lateral and medial eyes present.
A2 (Fig. 9e). Endopodite 3-segmented, first segment short with three short anterior setae; second segment elongated, with two long proximal setae; third segment elongated, reflexed, with two short setae near sclerotized beak-like tip.
Hemipenis (Fig. 9d). With rounded basal part carrying five seta-like structures and two hooks. An elongated process attached to the round base, curved distally and with seven teeth.
UL (Fig. 9c). Similar to female, except that the fourth claw being broader.
Remarks
Harbansus paucichelatus is the most widespread species of the genus. Kornicker (1984) noticed that it is very variable, so that it may represent a species-complex, and he considered the following features to be variable: primary claws on the UL can be stout or slender; shell may have many, few or no spines on the surface; exopod of A2 may bare long or short swimming setulae; tip of A2 endopod in female with or without terminal spine. Although Kornicker (1978) provided SEM photographs of the shell surface, it is impossible to discern on them peculiar structures detected in our specimens, i.e., small nodules within fossae interconnected with radial lines of dots. Our specimens all suffered from decalcification (due to improper sample fixation with non-buffered formaldehyde solution), as well as the ones that Kornicker (1978) illustrated. The Mexican specimens did not have any spines on the surface of the shell; the UL had stout claws; and the female A2 endopod lack terminal spine. We have also found that the average pairwise distances between 18S rDNA sequences of the new material and the one deposited on the GenBank is about 1 %, and between 28S rDNA sequences 2 %, which may also indicate a separate species (see Appendix 1), but this needs further studies as we cannot confirm identification of previously available GenBank sequences. Due to the high similarity in carapace shape and the morphology of other appendages, including A1 and hemipenis of our males and the ones reported by Kornicker (1984), we identified our specimens from Yucatan as H. paucichelatus. By providing mitochondrial COI sequence, we open a possibility for future molecular comparisons between our population and other populations of H. paucichelatus from its wide area of distribution.
Key to species of Harbansus
-
1.
Posterior infold with claw-like structures … H. ningalooi n. sp.
-
2.
Shell more than 2 mm long … H. magnus Kornicker, 1984
-
3.
Carapace not ornamented with fossae … 4
-
4.
Eight to 10 setae on the rostral infold … H. tenax Kornicker, 1995
-
5.
Five setae dorsally on the second endopod segment Md … H. ferox Kornicker, 1992
-
6.
Carapace with longitudinal ribs … 7
-
7.
Distal seta on the second endopod segment A2 absent … 8
-
8.
Five setae dorsally on second endopod segment Md and 6 setae on third endite L6 … H. slatteryi Kornicker, 1983
-
9.
More than six setae on rostral infold and three setae on the basal segment of endopod A2 … H. vortex Kornicker, 1995
-
10.
Six setae on the rostral infold … 11
-
11.
Seven setae on the second endopod segment Md and 7 setae on third endite L6 … H. schornikovi Kornicker and Caraion, 1977
-
12.
Three setae on each side of L7 terminus … H. vix Kornicker, 1991
-
13.
Three teeth on the peg side and 1 on the comb side of L7 terminus … H. flax Kornicker, 1998
-
14.
UL with more than 6 claws … H. hapax Kornicker, 1995
-
15.
Terminal segment of endopod A2 without setae or any other small extensions … 16
-
16.
Two setae on each side of terminus L7 … H. felix Kornicker, 1995
-
17.
Only one seta on the basal segment of A2 endopod and two setae on endite one L6 … H. bowenae Kornicker, 1978
-
18.
Three setae on each side of terminus L7 … 19
-
19.
Three setae on the basal segment of endopod A2 and 7 setae on the second endopod segment Md … H. barnardi Kornicker, 1978
-
20.
Four setae on the rostral infold … H. rhabdion Kornicker, 1970
Distribution of Harbansus
Most of the species have been reported only from their type localities, or nearby areas. The only exception is H. paucichelatus (Fig. 10) which has been collected from several localities in the Atlantic Ocean, from North Carolina to Belize (Kornicker 1978, 1984, Kornicker et al. 2002), at depths of 15 cm to 135 m. The present finding is from Mexico (Yucatan Peninsula), at 1.1 and 1.4 m. The new species is so far the only representative of the genus known from the coral reefs on the west coast of Australia, while another species, H. satteryi, was described from the Great Barrier Reef, Queensland (Kornicker 1983). The following species have been described from coral reefs around the world: H. hox from French Frigate Shoals (Kornicker et al. 2007a); H. trix and H. ferox from Mayotte coral reef area (Kornicker 1992); H. vix from Enewetak (Kornicker 1991); and H. flax from the Tuléar Reef (Kornicker and Thomassin 1998). The other 14 species are known from continental shelves and slopes, with H. rhabdion collected from deepest waters, i.e., 1,015 m at Peru–Chile trench (Kornicker 1970, 1978).
Molecular results
Pairwise distances of the COI sequences between four specimens of H. paucichelatus from the Yucatan Peninsula varied between 0 and 2 % (Table 2), which is indicative of intraspecific variation when compared to other crustacean groups (Lefébure et al. 2006). Since there are no other COI sequences belonging to this genus, or any species of the family Philomedidae, we did not provide any cladistic tree.
The aligned sequence data set of 18S rDNA contained 1930 bp, of which 246 bp was variable, while 172 bp was parsimony informative. Distances between 18S rDNA sequences of the 17 studied species varied between 0 and 8 % (Table 3), and those between previously available sequence of H. paucichelatus (AF363303.1) and our four specimens of the same species (H. paucichelatus F1, F2, M1, M2) was 1 %. The lowest pairwise distance was between some species of the genus Euphilomedes and between the Mexican specimens of H. paucichelatus. The greatest distance (8 %) was between the ingroup (Sarsielloidea) and outgroup taxa (Cypridinoidea). The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) is shown next to the branches (Fig. 11). The ML, NJ and MP trees did not share the same topology. The NJ supports the position of Rutiderma apex as basal to all other Euphilomedes (bootstrap value 87 %) and E. sordida 2 as basal to the rest of Euphilomedes (bootstrap value 78 %). Maximum parsimony places R. apex as basal to the entire ingroup, while E. sordida 2 represents a basal branch within the ingroup (bootstrap support 71 %). For the MP tree, bootstrap values for the consensus (50 % cutoff) of seven equally parsimonious trees are shown. The consensus tree had a length of 159 steps, the consistency index 0.786164, and the retention index 0.841121.
The aligned sequence data set of three 28S rDNA segments (dd/ff, ee/mm, and vv/xx) contained 2,356 bp, of which 487 bp was variable, while 231 bp was parsimony informative. Distances between 28S rDNA sequences of eight species varied between 1 and 18 % (Table 4), and the ones between H. paucichelatus from the GenBank (AF363303.1) and one specimen of the same species collected from the Yucatan Peninsula (H. paucichelatus M1) was 2 %. The lowest pairwise distance was between species of the genus Euphilomedes, and the greatest between the ingroup (Sarsielloidea) and the outgroup taxon (Cypridinoidea). The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) are shown next to the branches (Fig. 12), and the ML, NJ and MP trees shared the same topology. For the MP analysis, single most parsimonious tree had a length of 486 steps, the consistency index of 0.864198, and the retention index of 0.78.