Humphreysella phalanx (Kornicker & Iliffe 1995)

Danielopolina phalanx

ETYMOLOGY.—From the Greek phalanx (line, battle-array).

HOLOTYPE.—USNM 194126, undissected adult female in alcohol.

TYPE LOCALITY.—Sta 92-019, Atlantida Tunnel, Jameos del Agua lava tube, Lanzarote, Canary Islands; collected with plankton net from water in 9–21 m depth at 30-200 m penetration; salinity 37 ppt.

PARATYPES.—Sta 92-016: USNM 194125, adult female on slide and in alcohol. Sta 92-019: USNM 194127, 1 adult male on slide and in alcohol; USNM 194131, 1 undissected female in alcohol. Sta 92-030: USNM 194130, 1 undissected specimen in alcohol.

DISTRIBUTION.—Atlantida Tunnel, Jameos del Agua lava tube, Lanzarote, Canary Islands.

DESCRIPTION OF ADULT FEMALE (Figures 2–4).—Carapace subround in lateral view with straight dorsal margin in vicinity of hinge and slightly concave margin between anterior and anteroventral triangular processes (Figure 2c); ventral and posterior margins as well as anterior margin dorsal to anterior process evenly rounded. Short anterior and anteroventral processes with bases just lateral to valve edge; each process with cylindrical terminal process that easily breaks off and is absent from most specimens (terminal process on triangular anteroventral process shown in Figure 2c). Posterodorsal curvature of valves without processes.

Ornamentation (Figure 2a,c): Anterior surface between processes with 3 rows of minute papillae; anteroventral margin just within valve edge with 2 rows of minute papillae; parts of valve edge with indistinct minute triangular spines. (No reticulations were observed when shells were examined in original alcohol preservative prior to transferring to glycerine, which often renders reticulations invisible (Komicker and Iliffe, 1992:12); or on the holotype which, after being immersed in glycerine, was stained with dilute silver nitrate and photographic developer.)

Central Adductor Muscle Attachments (Figure 2d,e): Comprising about 8 attachments arranged more-or-less radially, but could be considered to be 2 opposing rows each with 4 attachments.

Carapace Size: USNM 194125, length including anterior triangular process 0.93 mm, height 0.68 mm. USNM 194126, length including anterior triangular process 0.95 mm, length excluding anterior triangular process 0.93 mm, height 0.67 mm.

First Antenna (Figure 2b,f): 1st joint with 2 bristles (1 long ventral with base on lateral side and ringed distally, 1 shorter dorsal). 2nd joint with distal medial spines and 1 dorsal bristle at midlength. 3rd and 4th joints fused, but place of fusion indicated by small indentation in dorsal margin near midlength. 5th joint with long filament-like terminal ventral bristle with minute widely spaced spines. 6th joint bare. 7th joint with 3 terminal bristles (unusually long ringed dorsal a-bristle with short marginal spines, 2 long filament-like ventral b- and c-bristles with widely spaced minute spines); a short peg may be present between b-bristle and 8th joint but not clearly resolved. 8th joint with 3 terminal bristles (slender dorsal d-bristle with short marginal spines, 1 long filament-like lateral e-bristle with widely separated marginal spines, and 1 long filament-like medial f-bristle narrower and shorter than e-bristle). Filament-like bristles weakly ringed proximally.

Second Antenna: Protopodite with fairly long bristle on posterior edge and long hairs in vicinity of proximal ventral corner (Figure 3a). Endopodite 3-jointed (Figure 3b): 1st joint with 2 ringed a- and b-bristles; 2nd joint with short ringed dorsal bristle with base on lateral side and 3 long filament-like terminal bristles near ventral margin; 3rd joint small, fused to 2nd, with short terminal bristle. Exopodite 9-jointed (Figure 3c): 1st joint divided into long proximal and short distal parts (see Komicker and Sohn, 1976:25); bristles of joints 2–8 with natatory hairs (some also with minute ventral spines); 9th joint with 2 bristles with minute ventral spines, longer bristle also with natatory hairs.

Mandible: Coxale endite with proximal and distal sets of teeth separated by a space (Figure 4a,b); proximal set comprising 4 cusps plus triangular tooth close to distal set of teeth; surface between cusps and medial and lateral surfaces just proximal to cusps with slender spines; 2 spinous bristles with bases just proximal and another bristle just distal to triangular tooth; distal set of teeth consisting of 2 flat teeth, each having 5 or 6 cusps; 1 slender spinous bristle with base proximal to distal set of teeth. Basale (Figure 4c,d): tooth of endite with 5 triangular cusps (all bare, or anterior 4 may have few very weakly developed teeth); posterior edge of endite spinous, with 2 short ringed distal bristles (distal of these tubular); anterior margin of endite with 1 long ringed bristle near midlength; lateral side of endite with 5 ringed bristles (4 long, 1 short) near midlength, and 1 short ringed distal bristle; medial side of endite with row of 3 pores or processes, long spines near anterior and posterior edges and near midlength, and 2 rows of shorter distal spines; medial side of basale near dorsal margin with 2 ringed bristles (ventral of these slightly broader at base and shorter), and with long spines near bristles; dorsal margin of basale with cluster of spines at apex. Endopodite 3-jointed (Figure 4c–e): 1st joint with medial and lateral spines, and dorsal bristle at midlength; 2nd joint spinous, with 1 ringed terminal ventral bristle, 2 ringed medial bristles near ventral margin, and 2 ringed dorsal bristles (proximal of these tubular); 3rd joint with dorsal and medial spines and 7 bristles (4 with bases medial, 3 with bases terminal (long middle bristle and ventral bristle claw-like)). (Rings not shown on all bristles.)

Maxilla: Endite I with 11 bristles (4 tubular) (Figure 4g; endite II with 6 bristles (some tubular) (Figure 4h); endite III with 5 bristles (2 tubular (Figure 4i) (tubular bristles not differentiated)). Coxale with long stout plumose dorsal bristle (Figure 4f). Basale with 2 long bristles (1 proximal ventral near base of endite III with widely separated long marginal hairs; 1 medial at joint midwidth) (Figure 4f). Endopodite (Figure 4f): 1st joint with proximal anterior spines, lateral spines at midlength, 3 long ringed distal anterior bristles, and 3 distal bristles (2 with bases lateral, 1 with base medial) near posterior margin; 2nd joint with 1 anterior stout straight nonarticulated terminal bare claw, 3 bristles with bases lateral (2 ringed (anterior bare; posterior with few minute indistinct spines) close to bare claw, and 1 stout proximal bare claw-like with distal rings), and 2 ringed bare tubular bristles with bases medial.

Fifth Limb (Figure 3d,e): Epipodite with 3 groups of plumose bristles, each group with 4 bristles. Protopodite with 5 bristles (1 tubular). Basale with 6 bristles (1 short claw-like, 2 long plumose, 1 slender medial proximal, 2 slender ventral tubular). Endopodite with 6 bristles (1 small medial tooth-like, 2 long sclerotized ventral claw-like, 2 long plumose ringed ventral, 1 ventral tubular). Exopodite 3-jointed: 1st joint with 9 bristles (6 ventral (3 at midlength, 3 terminal), 2 lateral at joint midheight (1 at midlength, 1 terminal), and 1 very long dorsal terminal); 2nd joint with 2 ventral bristles at midlength; 3rd joint with 3 bristles (middle bristle about 53% and smallest bristle about 28% of longest bristle).

Sixth Limb (Figure 3f): Epipodite with 3 groups of plumose bristles (2 dorsal groups each with 4 bristles, ventral group with 5). Precoxale with 2 plumose bristles. Coxale with 2 plumose bristles. Basale with 4 bristles (1 bare, 3 plumose). Small endopodite with 2 bristles (shorter bristle plumose; longer bristle more than 2 times length of other and plumose proximally). Exopodite: 1st and 2nd joints fused, with medial hairs, and 2 long bare ventral bristles at midlength; 3rd joint with 3 bare bristles (2 short bristles 18%-26% of longest bristle).

Seventh Limb (Figure 2h): Elongate with 2 terminal bristles.

Furca (Figure 2h,i): Each lamella with 7 claws. Claws 1–3 anterior, articulated, and weakly ringed; claw 4 on anteroventral comer, nonarticulated, and weakly ringed; claws 5–7 ventral, nonarticulated, and unringed. All claws with minute teeth along posterior edges, some also with smaller teeth along anterior edges. Each lamella with lateral and medial rows of minute spines (only few shown). Stout unpaired process on posterior of body just proximal to lamellae.

Bellonci Organ (Figure 2b,g): Elongate, well developed, and visible through translucent valves.

Lips: Typical for genus.

Anterior of Body: With small triangular process on each side dorsal to upper lip.

Posterior of Body (Figure 2h,i): Appearing segmented.

Genitalia: Not observed.

DESCRIPTION OF ADULT MALE (Figures 5–7).—Shape, ornamentation, and central adductor muscle attachments similar to those of adult female (Figure 5a,b).

Carapace Size: USNM 194127, separated right valve, length with anterior process 0.86 mm, length without anterior process 0.83 mm, height 0.57 mm.

First Antenna (Figure 6a,b): 1st joint with 2 bristles (1 long ventral with base on lateral side and ringed distally, 1 shorter dorsal). 2nd joint with distal medial spines and 1 dorsal bristle near midlength. 3rd and 4th joints fused, but place of fusion indicated by small indentation in dorsal margin and by 3rd joint being wider; 4th joint with 2 long ventral filament-like bristles. 5th joint with 3 filament-like bristles (ventral of these slightly broader and with closely spaced distal spines (short triangular spines followed by longer slender curved hair-like spines (detail in Figure 6a))). Joints 6–8 similar to those of adult female.

Second Antenna: Protopodite similar to that of adult female (Figure 5c). Exopodite similar to that of adult female except left limb of USNM 194127 with only 8 joints. Endopodite 3-jointed (Figure 5c,d): 1st joint with 2 ringed a and b-bristles; 2nd joint with short ringed dorsal bristle with base on lateral side and row of 4 long filament-like terminal bristles near ventral margin; 3rd joint small, fused to 2nd joint, with elongate terminal process with 2 minute indistinct unringed bristles at sclerotized tip (row of minute spines may be present on tip but not resolved with certainty).

Mandible (Figure 6c): Similar to that of adult female except basale endite with only 2 pores in medial row, 2nd endopodial joint shorter, and ventral claw-like bristle of 3rd endopodial joint with slightly stouter marginal spines at midlength.

Maxilla: Similar to that of adult female but endite bristles not counted.

Fifth Limb (Figure 7a): Epipodite with 3 groups of bristles (dorsal group with 5 bristles, 2 ventral groups with 4). Limb otherwise similar to that of adult female.

Sixth Limb (Figure 7b): Limb similar to that of adult female.

Seventh Limb: Right limb of USNM 194127 with 2 bristles (Figure 6d); left limb aberrant in having 3 bristles (Figure 6e).

Furca (Figure 6d,f): Similar to that of adult female except claw 4 articulated, and left lamella of USNM 194127 with additional ventral claw; total number of claws 7 or 8. Stout unpaired process on posterior of body just proximal to lamellae.

Bellonci Organ (Figure 6b): Similar to that of adult female.

Lips: Typical for genus.

Anterior and Posterior of Body: Similar to those of adult female.

Genitalia (Figures 6d,g, 7c): Anterior part with long curved process tapering to narrow tip (tip broken off in Figure 7c). Styliform process not observed with certainty (obscured).

COMPARISONS.—The carapace of D. phalanx differs from that of D. wilkensi Hartmann, 1985, in not having a posterodorsal process on each valve and in being larger, as well as in not having a reticulate surface. The furca of D. phalanx has 3 or 4 articulated anterior claws compared to 2 for D. wilkensi. The carapace of D. mexicana Komicker and Iliffe, 1989a, differs from that of D. phalanx in having a posterodorsal process on each valve. Danielopolina phalanx is the only known species in the genus having more than 2 anterior articulated furcal claws (3 on adult female, 4 on adult male).