“Eusarsiella iayx, new species
ETYMOLOGY.—From the Greek iayx (northwest wind).
HOLOTYPE.—Partly dissected ovigerous female in alcohol in the collection of the Museum of Victoria.
TYPE LOCALITY.—Slope 48, 41°57.50’S, 148°37.90'E, Tasmania, off Freycinet Peninsula; depth 400 m.
PARATYPES.—Slope 22: USNM 194044,1 ovigerous female on slide and in alcohol; 1 ovigerous female + 4 adult females in alcohol. Slope 40: USNM 193986,1 ovigerous female on slide and in alcohol; 11 adult females (10 ovigerous) in alcohol. Slope 46: 1 late instar in alcohol. Slope 47: 1 adult female with choniostomatid copepods (1 female, 1 male, 1 egg sac containing well developed copepodites) in marsupium. Slope 48: USNM 194021, ovigerous female on slide and in alcohol; USNM 194022, partly dissected ovigerous female in alcohol; unnumbered specimens: 3 ovigerous female + 3 adult females + 3 juveniles, all in alcohol.
NONTYPE.—Slope 40: USNM 193988,1 adult male on slide and in alcohol.
DISTRIBUTION.—Slope 22, 363 m. Slope 40, 400 m. Slope 46, 720 m. Slope 47, 500 m. Slope 48, 400 m. Known depth range 363-720 m.
DESCRIPTION OF ADULT FEMALE.— Carapace with bulbous posterodorsal bulge on each valve and moderate size caudal process.
Ornamentation: On some specimens posterodorsal bulge bearing thin rib, but on others (including holotype) ridge absent. Surface with minute spines along edges, and with more lateral bristles than on either E. bex or E. edax, but not abundant.
Bristles of 3 types: (1) bristles with stout triangular base, or thicker in proximal 1/3 or 1/2 and with angular bend just distal to stout part; (2) undivided slender bristles (sparse); (3) divided slender bristles slightly broader at base and with 1 branch much shorter than other (the divided bristles characterize the species); divided bristles absent along edges of valve. Outer surface without jell-like coating.
Infold: Anterior infold with 1 small bristle near inner margin ventral to midheight. Infold anterior to caudal process with 3-6 small bristles plus 5 bristles along inner margin. Dorsal to caudal process 2 setal bristles, and 1 slender bristle on inner margin dorsal to setal bristles.
Central Adductor Muscle Attachments: Comprising about 20 ovoid attachments.
Carapace Size (mm): Slope 22: USNM 194044, length with caudal process 1.27; height without caudal process 1.21. Slope 40: USNM 193986, length with caudal process 1.43, length without caudal process 1.40. height without caudal process 1.24. Slope 47: unnumbered specimen, length with caudal process 1.69, length without caudal process3.61, height without caudal process 1.43. Slope 48: holotype, length with caudal process 1.77, length without caudal process 1.71, height without caudal process 1.53; USNM 194021, length with caudal process 1.68, length without caudal process 1.55, height without caudal process 1.43; USNM 194022, length with caudal process 1.48, length without caudal process 1.44, height without caudal process 1.53. Range of length considerable (with caudal process) 1.27-1.77 mm.
First Antenna: 1st joint long, bare. 2nd joint with proximal dorsal spines, spinous dorsal bristle, and row of few indistinct short lateral hairs on distal edge near dorsal margin. 3rd joint fused with 4th, with 2 spinous bristles (1 ventral, 1 dorsal). 4th joint without dorsal hairs, with 3 or 4 spinous bristles (2 or 3 ventral (on USNM 193986 both bristles short, but on holotype and USNM 194044 one bristle extends past 8th joint), 1 dorsal). Sensory bristle of 5th joint with 2 single closely spaced minute spines at midlength. 6th joint fused to 5th, with small medial bristle near dorsal margin. 7th joint: a-bristle 3-5 times length of bristle of 6th joint, with few distal spines; b-bristle almost twice length of a-bristle or longer, bare; c -bristle same length as sensory bristle of 5th joint, with minute filament at 1/3 length, and 2 single minute closely spaced spines at midlength. 8th joint: d- and e-bristles slightly shorter than c -bristle, bare with blunt tips; f-bristle about same length as d-bristle, bare; g-bristle about same length as c -bristle, with 1 or 2 minute spines at midlength; sensory bristle of 5th joint, and b-, c-, f, and g-bristles of 7th and 8th joints with minute spine or filament at tip.
Second Antenna: Protopodite bare. Endopodite with 2 slender proximal bristles with few small spines, and 1 minute unringed terminal bristle (on USNM 193986 bristle is not on node, but node present on holotype, USNM 194021, USNM 194044, and USNM 194022). Exopodite (USNM 193986): left limb: 1st joint with small terminal medial fairly straight tubular bristle; bristle of 2nd joint long with about 21 proximal ventral spines and distal natatory hairs; bristle of 3rd joint with 3 proximal ventral spines and distal natatory hairs; bristle of 4th joint with natatory hairs, no spines; bristle of 5th joint with 4 proximal ventral spines and distal natatory hairs; bristle of 6th joint with few proximal ventral hairs then 6 ventral spines and distal natatory hairs; bristle of 7th joint with 12 proximal ventral spines and distal natatory hairs; bristle of 8th joint with few proximal ventral hairs, then 11 ventral spines and distal natatory hairs; 9th joint with 2 bristles (1 long with natatory hairs, 1 short (dorsal) with short hairs); joints 2-8 with few minute spines along distal edge. Exopodite of right limb: bristle of 2nd joint with 20 proximal ventral spines and distal natatory hairs; bristles of joints 3 and 4 with natatory hairs, no spines; bristles of joints 5-8 with proximal ventral spines (not counted) and distal natatory hairs; 9th joint similar to that of left limb. Exopodite (holotype): bristle of 2nd joint with only 5 proximal ventral spines, some other bristles with few spines but these not counted.
Mandible: Similar to that of E. edax except for small medial spine-like bristle near base of claw of 1st endopodial joint (examined 3 specimens but not holotype), no ntral teeth on claw of 3rd endopodial joint, and no exopodite.
Maxilla and Fifth Limb: In general, similar to those of E. edax.
Sixth Limb: Single endite with 3 bristles (2 medial, 1 longer terminal). End joint with 14-16 spinous bristles followed by space and 2 long plumose bristles; limb hirsute along proximal posterior edge and medially on posterior half.
Seventh Limb: Proximal group usually with 4 bristles (2 on each side), but one limb of holotype with 5 bristles, and one limb of USNM 194021 with 7; each bristle with 4 or 5 bells; terminal group with 6 bristles (3 on each side), each with 4-7 bells. Terminus with opposing combs, each with about 8 indistinct teeth; prominent node present at midpoint of terminus.
Furca, Bellonci Organ, Eyes, Genitalia, Anterior of Body, Posterior of Body, and Y-Sclerite: Similar to those of E. edax, except Bellonci organ of USNM 194044 with thinner and more tapered tip.
Upper Lip: Comprising 2 adjacent bare lobes projecting anteriorly; left lobe usually longer.
Number of Eggs: Slope 22: USNM 194044 with 4 well-developed eggs in marsupium (length of typical egg 0.37 mm) and 1 unextruded egg (length 0.21 mm) (location of 1 egg in marsupium shown in Figure 84ft). Slope 40: USNM 193986 with 4 eggs in marsupium (length of typical egg 0.25 mm) (location of 1 egg shown in Figure 83a). Slope 48: holotype with 3 eggs (all in posterodorsal bulge of left valve) (length of typical egg 0.28 mm). Slope 48: USNM 194021 with 5 eggs in marsupium (length of 1 egg including transparent sac 0.29 mm (length excluding transparent sac 0.22 mm); USNM 194022 with 4 eggs in marsupium (length of 1 egg 0.22 mm).
Parasites: Female from Slope 47 with choniostomatid copepods (1 female, 1 male, 2 egg sacs with well-developed copepodites (length of 1 sac 0.29 mm), 1 egg sac with round eggs (length 0.18 mm)).
DESCRIPTION OF ADULT MALE.—Carapace similar to that of E. bex.
Ornamentation: With fewer bristles than on adult female and without divided bristles.
Infold: Infold of caudal process with 4 small bristles (3 anterior, 1 posterior) and 3 small bristles along inner margin of infold. No bristle present dorsal to 2 setal bristles on posterior infold.
Carapace Size (length (including caudal process), height in mm): USNM 193988, 1.39,1.03.
First Antenna and Mandible: Similar to those of E. bex.
Second Antenna: Protopodite differs from that of E. bex in having more medial spines near endopodite. Endopodite and exopodite similar to those of E. bex.
Maxilla and Fifth Limb: Reduced (not examined in detail).
Sixth Limb, Seventh Limb, Furca, Bellonci Organ, and Eyes: Similar to those of E. bex.
Upper Lip: With anterior projection with small process on each side, each with 2 or 3 small spines.
Genitalia, Anterior of Body, and Posterior of Body: Similar to those of E. bex.
Remarks: Females referred to this species are quite variable in size of carapace, and it is possible that more than one species has been included. Seventh limbs of five specimens examined (holotype, USNM 194021, USNM 194022, USNM 194044, and unnumbered specimen from Slope 47) have a large node between the opposing terminal combs, which is uncommon among species of the genus. Only specimens having divided bristles on the lateral surface of the carapace are referred to the species. Divided bristles were observed on adult females and on the A-l and A-2 instars, but not on the adult male. The adult male identified as E. iayx is not referred to the species with a high degree of certainty, and therefore, is designated a nontype. Carapaces of juveniles are without a posterodorsal bulge.
COMPARISONS.—The shape of the carapace of the female E. iayx is similar to that of E. edax, but the posterodorsal bulge of E. iayx does not have the 2 ribs present on E. edax. The carapace of E. iayx bears divided bristles absent on both E. edax and E. bex. The 7th limb of E. iayx usually bears 4 proximal b-bristles compared to seven or eight on E. edax, and a prominent node present at the midpoint of the terminal end of the limb is absent on E. edax (a node present on some limbs of E. fallomagna). The bristle of the 2nd exopodial joint of the 2nd antenna of E. iayx bears proximal ventral spines absent on E. edax.
The posterodorsal process on the carapace of E. bex is less globose then that of E. iayx, and the dorsal margin of the 4th joint of the 1st antenna of the female E. bex bears minute spines absent on E. iayx. No large differences were observed between the adult males E. iayx and E. bex, and they may by conspecific; however, they are interpreted to be different species because each occurred in a sample with females of the two different species to which they have been referred to herein, and because males of closely related sarsiellids are often more similar to each other than are females.”
(Kornicker, 1994, p.145-149)