Euphilomedes chupacabra Lum, Syme, Schwab & Oakley, 2008, new species

• Main Authors: Lum, Kimberly E., Syme, Anna E., Schwab, Anastasia K., Oakley, Todd H.
• Format: Text
• Language: unknown
• Published: Zenodo 2008
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Ostracoda; Myodocopida; Philomedidae; Euphilomedes; Euphilomedes chupacabra; Antarctic; Indian; New Zealand; Lizard Island; Seta; Todd; Pillar; Briggs; Rivera; Unwin; Strong Peak; Moon Bay; Half Moon Bay; Antarc*
• Online Access: https://dx.doi.org/10.5281/zenodo.6233864; https://zenodo.org/record/6233864

Euphilomedes chupacabra , new species Figures 1–4. Etymology: Named after the “ chupacabra ” legend, which began in Puerto Rico, the type locality of the species. Holotype: SBMNH # 83215 one dissected ovigerous female on two slides, carapace in alcohol. Type locality: Isla Magueyes, Puerto Rico, 17 ° 54 ' – 17 ° 58 ' N, 67 °03' – 67 °04' W, 2–20 m depth, collected by K. Lum, A. Schwab, and T. Oakley, using hand nets, July 2005. Paratypes: SBMNH # 83216 one dissected adult male on one slide, carapace in alcohol; SBMNH # 83218 one dissected adult female on one slide, carapace in alcohol; SBMNH # 83217, 10 specimens in alcohol; all collected in the same way as the holotype. Of the 10 paratypes of SBMNH # 83217, the carapace measurements in mm (l=length, h=height) are as follows: five adult females, l= 1.69 h= 1.21, l= 1.51 h= 0.91, l= 1.55 h= 1.06, l= 1.49 h=1.00, l= 1.54 h= 1.06; two adult males, l= 1.43 h= 0.81, l= 1.43 h= 0.81; three juveniles of uncertain instar stage, l= 0.81, h= 0.66, l= 0.81 h= 0.60, l= 0.91 h= 0.66. Distribution: Known at present only from type locality. Diagnosis: Anteroventral infold on female carapace with striations; seventh limb with eight setae; furca with primary claws 1,2, 4 and 6; Y-sclerite with anterior triangular structure. Description of adult female (holotype). SBMNH # 83215. This has been compared to paratype SBMNH # 83218 and any differences are noted in the text. Carapace (Fig 1 A). Ornamentation: Carapace with setae on surface; no pits or grooves visible at X 40 magnification. Rostral infold with row of six setae. Anteroventral infold with striations and no setae. Ventroposterior infold with row of 12 triangular setae, then space, then five triangular setae (setae not shown). Carapace size: length 1.80 mm, height 1.26 mm. Paratype SBMNH # 83218 carapace size: length 1.66 mm, height 1.15 mm. First antenna (Fig 1 B). Article one with long medial hairs. Article two with two dorsal spines (none on paratype SBMNH # 83218), six ventral spines (seven on paratype SBMNH # 83218), and three setae (one ventral, one dorsal, one lateral) with long spines. Article three with one ventral seta with spines, and two bare dorsomedial setae. Article four with medial spines, three ventral spines, four ventral setae: two long (approximately four times ventral margin of article four), one medium, one short, all with long spines (bases represented by circles); one bare dorsal seta, and one dorsal seta with one long and several short filaments. Article five with sensory seta with five short marginal filaments, three longer subterminal filaments, and bifurcate tip (sensory seta is obscured on paratype SBMNH # 83218 and has not been compared). Article six with medial seta with short marginal filament (no marginal filament on paratype SBMNH # 83218). Article seven a-seta similar length to sixth article medial seta, with short proximal and long terminal filaments (no terminal filaments on paratype SBMNH # 83218); b-seta with seven (six on paratype SBMNH # 83218) marginal filaments and bifurcate tip; c-seta with 11 (seven on paratype SBMNH # 83218) marginal filaments and bifurcate tip. Article eight with d- and e-setae with fine marginal terminal filaments and blunt tips; f-seta with five marginal filaments and bifurcate tip; g-seta with five marginal filaments and bifurcate tip (article eight is obscured on paratype SBMNH # 83218 and has not been compared). Second antenna (Fig 1 C). Protopod without e-sclerite; with two clusters of spines on dorsal margin. Endopod with two articles. Article one with five proximal and one distal seta. Article two with one long spinous proximal ventral seta and one short bare distal seta. Exopod with nine articles. Articles two to eight with comb of short spines on medial terminal margins (not shown). Articles three to eight with ventral spines (not shown) and with long setae. Seta on article two with fine filaments. Setae on articles three and four with short spines. Setae on articles five to eight with long spines (not shown) (=natatory hairs). Article nine with seven setae: one bare, short; one medium with short spines; five long with long spines (all spines, filaments not shown). Mandible (Fig 2 A). Coxale endite with bifurcate tip and cluster of spines at base. Seta near base not observed on holotype but present on paratype SBMNH # 83218, small lateral spine dorsal to coxale endite. Basale ventral margin with proximal clusters of spines, six ventral setae (seven on paratype SBMNH # 83218), six medial setae, three dorsal setae (one at midlength, two terminal). Exopod with two spinous setae (one four times length of other). Endopod article one with four ventral setae (three long spinous, one short bare); article two with five medium-length ventral setae and with eight dorsal setae: proximal (one medium, one long), distal (one short, two medium, three long) (on paratype SBMNH # 83218, two short, one medium, three long); article three with three unringed claws (two longest with minute teeth on ventral margin) and three setae. Maxilla (Fig 2 B). (Maxillae obscured on paratype SBMNH # 83218 and not compared here.) Precoxale with fringe of hairs along dorsal margin. Coxale also with fringe of hairs along dorsal margin and with one spinous (=plumose) seta. Basale with three terminal spinous setae: one dorsal, one medial, one ventral (bases of ventral and medial setae represented by circles). Exopod with two long (one broken) and one short seta, all spinous (spines not shown). Endopod article one: one spinous alpha seta. Four bare beta setae (bases represented by circles). Article two with three a-setae (bases represented by circles), three claw-like setae (not shown), one b-seta (base represented by circle), and two c-setae (not shown). Arrangement similar to that of E. morini (discussed in Kornicker & Harrison-Nelson 1997). Endite I with eight setae, endite II with five setae, endite III with five setae. Fifth limb (Fig 2 C). Notes: The homology of fifth limb components was discussed by Kornicker (2002). As no species of Euphilomedes have been described after that work, however, and it is difficult to compare the fifth limb on this specimen with the homologies discussed there, the previous terminology has been applied herein. Arrangement similar to that of E. morini (Kornicker & Harrison-Nelson 1997). Epipod with about 50 setae. (Endites obscured on paratype SBMNH # 83218 and not compared here.) Coxale endite I with four spinous setae (spines not shown). Coxale endite II with six spinous setae (spines not shown). Coxale endite III with about 12 spinous setae (spines not shown). Exopod article one: anterior side with two setae with long spines (not shown, bases are dotted circles) on distal edge; outer corner with two small setae (not shown); main tooth one seta proximal to teeth, four slender pointed teeth and one large distal tooth with four prongs. Exopod article two posterior side with one proximal seta with distal hairs, three distal setae (middle seta long, others short). Exopod article three inner lobe with three spinous setae (spines not shown), outer lobe with one broken seta (but two long spinous setae present on paratype SBMNH # 83218). Exopod articles four and five fused with seven spinous setae (some broken). Sixth limb (Fig 3 A). Limb not hirsute. Epipod with three spinous setae. Endite I with three spinous setae (one long lateral, one medium medial, one short medial). Endite II with three setae. Endite III with nine setae. Endite IV with eight setae (paratype SBMNH # 83218 with nine). End article with 19 spinous setae (paratype SBMNH # 83218 with 18). Seventh limb (Fig 3 B). Proximal and terminal groups of four setae each, each seta with 4–6 bells; terminal comb with about seven teeth; two pegs present opposite comb, inner of these spinous and slightly longer than outer peg. Furca (Fig 3 C). Each lamella with 11 claws: claws 1,2, 4 and 6 primary, remaining claws secondary. Claw one with large teeth along posterior margin; claws three and five with small teeth along anterior and posterior margin; remaining claws with small teeth along posterior margin; hairs present at base of claws (hairs not drawn). (Posterior of body and genitalia lost during dissection of paratype SBMNH # 83218 and not compared here.) Y-sclerite bifurcates at anterior tip into triangle. Genitalia: two ovals with pigmented centers. Eggs or embryos: 24 eggs or embryos within carapace (no limbs or structures visible within). Amongst other material we collected, we observed 9 broods, which ranged in size from 7 to 24 embryos. Anterior of body not examined on SBMNH # 83215; on adult female of SBMNH # 83217 the anterior process is hornlike. Posterior of body: bare. Medial eye (Fig 3 D) with dark pigment. Bellonci organ with no obvious sutures. Lateral eye is rudimentary without obvious ommatidia and contains a red pigment that disappears when animals are fixed in ethanol. Because these rudimentary eyes are only visible in living specimens, and because we could not illustrate specimens while doing field work, we cannot present illustrations or measurements of the female lateral eye at this time. Description of adult male. SBMNH # 83216. Similar to female except for differences noted here. Carapace (Fig 4 A). Anteroventral margin with no striations. Carapace size: length 1.60 mm, height 0.94 mm. First antenna (Fig 4 B). Article one with no long medial hairs. Article two with three setae (one spinous ventral, one bare dorsal, one bare lateral). Article three with one bare ventral seta and two bare dorsomedial seta. Article four with four ventral setae and two dorsal setae. Article five with sensory seta with approximately 30 proximal filaments (not all filaments shown), one distal filament and bifurcate tip. Article six with medial seta. Article seven b-seta with two distal filaments and bifurcate tip, c-seta 2.5 X length of first antenna. Article eight f-seta 2.5 X length of first antenna, g-seta with four marginal filaments and bifurcate tip. Second antenna (Fig 4 C): Protopod with e-sclerite. Endopod with three articles. Article one with five proximal and one distal seta. Article two with two setae. Article three recurved, with one long proximal and two short distal setae. Mandible: coxale endite reduced, consisting of two small bristles; basale hirsute. Maxilla: not observed; either lost from specimen or reduced or absent. Fifth limb: reduced; endites I-III with approximately three setae each; no main tooth, remainder of limb with six setae in total. Furca: each lamella with 10 claws: claws 1,2,4,6 primary, remaining claws secondary. Genitalia (Fig 4 D): elongate paired copulatory limbs divided distally into two lobes with three terminal setae. Lateral eye with approximately 20 pigmented ommatidia. Remarks. The striated inner margin of the female carapace may prove to be a useful taxonomic character; it has been reported in approximately half of the existing species descriptions in Euphilomedes (its omission in descriptions may not indicate an absence of the feature, and investigation of original material could clarify this). It does not appear to be present on the male carapace. We speculate that the striations may accommodate the setae of the second antennae exopods when in a resting state. However, this speculation does not explain why males lack these striations. Adult males of E. chupacabra lack a red pigmented rudiment distal to the lateral eye that is visible in live specimens of E. carcharodontus. E. morini adult males also lack this rudiment, which is present in juvenile male E. morini (Rivera and Oakley, submitted). It is unknown to us whether or not E. chupacabra juvenile males possess this rudiment. When live male specimens are available, the distal rudiment may prove to be a valuable taxonomic character within Euphilomedes . Comparisons . E. chupacabra differs from other species in the genus in the unique combination of characters stated in the diagnosis. More specifically, other species in the genus can be further differentiated from it by these features: E. africanus and E. japonicus adult females have no distal seta on the second antenna endopod article two; E. asper, E. nipponicus and E. bradyi have 10–12 setae on the seventh limb and only furcal claws 1, 2 and 4 as primary; E. pseudosordidus has 9–10 furcal claws with only 1,2 and 4 as primary; E. nodosus lacks a lateral seta on the first antenna article two; E. carcharodontus has 10 setae on the seventh limb and the furcal primary claws are 1,2,3,5; E. erynx has 11 setae on the seventh limb and furcal primary claws are 1,2,3,5; E. kornickeri has two (not one) ventral setae on the first antenna article three, and the male lacks a proximal seta on the second antenna endopod article three; the proximal seta on the second antenna endopod article two of E. longisetus has a very wide base; E. debilis is smaller (the male carapace is 1 mm long) and the furcal primary claws (although not described) appear in the figure to be 1,2, 4 and 8; E. smithi has 10 setae on the seventh limb and 13 pairs of furcal claws; E. climax, E. cooki and E. walfordi have more than 13 setae on the seventh limb; E. morini has an unusual axe-shaped Y-sclerite and 10 setae on the seventh limb; and the remaining species have distinctive features of the carapace: E. corrugatus has deep grooves and pits; E. sordidus has large pits; E. ijimai has two posterior processes; E. producta has a sclerotized triangular process; E. sinister sinister and E. sinister pentathrix have a small posterior tooth. Ecology, behavior, density. We first discovered this species by accident while obtaining sea water by dipping a bucket after sunset adjacent to the pier at the Isla Magueyes Marine Lab of the University of Puerto Rico-Mayaguez. Subsequently, we hypothesized that individuals were abundant in the plankton after sunset. We tested this hypothesis by dragging a rectangular aquarium net (opening size 24.5 x 17.0 cm) along a 9.6 m transect adjacent to the pier, thus sampling a water volume of 0.4 m 3 with each pass of the net. At each sampling time, we made two passes (collections) with different nets and transferred ostracods from the nets to beakers to Petri dishes and counted individuals, averaging over the two passes. We collected 1–9 times per night, usually at 15 minute intervals; the earliest collection time was 04: 30, the latest 23: 55 local time. We collected on 18 non-consecutive nights between June 21, 2005 and July 25, 2005. For these behavioral observations, we returned individuals to the collection site alive each night after counting, so as not to deplete the local population. The water depth at the site was 1.2 m. The vast majority of individuals collected in this manner appeared to be male Euphilomedes chupacabra . Out of a total of 4857 ostracods, 4432 were male E. chupacabra and 2 were female E. chupacabra 362 appeared to be a single unidentified cylindroleberidid species; 56 appeared to be two different unidentified rutidermatid species; 5 were unidentified podocopa (Tables 1–3). Each night, there was a strong peak of activity of E. chupacabra at about 100 minutes after sunset. We assumed the distribution of males over time was normal, using JMP statistical software to fit a Gaussian distribution and estimate two parameters for the data from each night. The timing of peak activity ( t ) was estimated for each night’s collecting from normalized curves. Estimates of t ranged from 85 to 130 (average = 103.6, sample size of 18 days) minutes after sunset. No animals were present in the samples at the latest (600 minutes after sunset) or earliest (pre-sunset) collecting times. We did not collect near sunrise. The earliest an individual was collected was at 64 and the latest at 202 minutes after sunset. The densities of individuals ( d ) were estimated as the height of the normalized curves from each night’s collecting. Estimates of d in the sampled area ranged from 24 to 862 males/m 3. No association was apparent between density or peak activity time and lunar cycle (Fig 5). We had a very limited sample for detecting such associations, however, and the pier lights may have obscured moonlight or altered normal behavior. Since collection was only possible for a one month period, the possibility of seasonality in population density or swimming activity remains open. TABLE 1. Raw collecting data for two collecting passes (1, 2) in number of individuals counted per taxon. to be continued. to be continued. * Cloud Scale: 0=Clear; 1 =Partly cloudy; 2 =Cloudy, moon visible; 3 =Cloudy We also hypothesized that the population of ostracods at our primary collection site was inflated artificially by bright lights above the pier. This hypothesis was supported by our inability, albeit in very few attempts, to collect more than a few ostracods in nonilluminated water near peak activity times adjacent to the same pier. In addition, we tested the hypothesis by taking advantage of sexual dimorphism in the species. Males spend more time in the plankton and have compound eyes, and are therefore more likely to be concentrated at lights than females. If so, the proportion of males to females would be significantly higher in sediment under the pier lights compared to other collecting sites. Based on the average of four semi-quantitative samples of sediment taken under the pier lights, six times as many adult males as adult females were present. In 62 semiquantitative samples (Table 3) of sediment away from the pier lights in various microhabitats, males were less common than females (ratio = 0.84). This difference is highly significant in statistical analyses of a 2 x 2 contingency table, indicating that males were concentrated relative to females under the pier lights. These results indicate that males are attracted to pier lights but do not test whether females are also attracted there. In a similar test comparing adult females to juveniles under the pier and elsewhere, we were unable to reject the null hypothesis of equal ratios (Table 3). These observations provide no evidence that females are also attracted to lights, but this could be tested further in laboratory experiments. Site Date GPS Description/Field Notes (2005) Site 1 Isla Magueyes Pier - light side (night - male) Site 2 Isla Magueyes Pier - dark side (night - male) Site 3 Isla Magueyes Pier - end (day - female) Site 4 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft depth) Site 5 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft depth) Site 6 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft) Site 7 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft) Site 8 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft) Site 9 6 / 23 N 17 ° 56.587, W 67 ° 4.674 San Cristobal (10ft) Site 10 6 / 24 n/a Mario- (10ft) nearby hexacoral, coral, some staghorn coral Site 11 6 / 24 n/a Mario: (11ft) nearby brain coral, some staghorn, some bottlebrush? coral Site 12 6 / 24 N 17 ° 57.455, W 67 ° 3.409 La Palma- (45 ft) murky sediment, nearby purple thin finger coral Site 13 6 / 24 N : Published as part of Lum, Kimberly E., Syme, Anna E., Schwab, Anastasia K. & Oakley, Todd H., 2008, Euphilomedes chupacabra (Ostracoda: Myodocopida: Philomedidae), a new demersal marine species from coastal Puerto Rico with male-biased vespertine swimming activity, pp. 35-57 in Zootaxa 1684 on pages 36-54, DOI: 10.5281/zenodo.180473 : {"references": ["Kornicker, L. 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