Chelicopia radix Kornicker 1992

Chelicopia radix

ETYMOLOGY.—From the Latin radix (root).

HOLOTYPE.—MNHN Os 459, undissected instar IV female in alcohol.

TYPE LOCALITY.—Sta 124-S, 12 Apr 1977, Mozambique Channel, SE Glorioso Islands, 11°32′06″S, 47°23′06″E, depth 24 m.

PARATYPES.—Sta 106-R: USNM 193712, 1 instar IV male instar on slide and in alcohol; 1 instar IV ?female. Sta 124-S: USNM 193711, 1 instar IV female on slide and in alcohol; Paris, 1 instar IV undissected female in alcohol.

DISTRIBUTION.—Sta 106-R, Zelee Bank, south border, depth 18–24 m. Sta 124-S, Mozambique Channel, SE Glorioso Islands, depth 24 m. Known depth range 18–24 m.

DESCRIPTION OF INSTAR IV FEMALE (Figures 87, 88).—Carapace oval in lateral view with slight flattening of posterodorsal margin (Figure 87a). Projecting caudal process absent but caudal area indicated by extremely slight flattening of posteroventral corner of valve margin viewed laterally (Figure 87a), and valve edge slightly concave when viewed medially (Figure 87b,d,e); valve margin in caudal area also marked by long slender bristles more numerous than elsewhere (Figure 87a,d).

Ornamentation: In transmitted light shell with abundant small ring-like structures, each with diaphanous “skirt” with digitate edge (Figure 87a) (skirt easily visible when structure viewed from side (detail at lower left of Figure 87a), but in end view only digitate edge visible, and only barely so (detail at lower right of Figure 87a). Number of digitations range from about 2 to 10. Skirts vary in length from being about equal to ring diameter at base of structure to about 5 times ring diameter; the latter type present along posterior edge of shell and appear stalk-like (Figure 87d). Short thumb-like processes, with same diameter as ring-like structures, form single row along anterodorsal, anterior, and anteroventral valve edges (Figure 87c); surface of valves without gelatinous coating.

Surface Bristles: Bristles sparsely distributed on outer surface of valves, more numerous along anterior and ventral margins, and especially abundant along outer margin of caudal area (Figure 87a,d). Bristles of several types: short and long slender bristles without surface structures; short and long bristles with short broad part bearing transverse ribs (broad part near midlength on long bristles and on some short bristles, and proximal on most short bristles); some bristles bending sharply just distal to broad part but other bristles straight (Figure 87c,d). Anterior and ventral margins of valves overhanging valve edge (Figure 87b); inner surface of overhang (inward from row of short thumb-like processes) with numerous small spines pointing outward, short bristles (with stout ribbed proximal part) forming row near valve edge, and longer bristles (with stout ribbed part near midlength) forming outer row (Figure 87c). Minute spines present on outside surface of valves just proximal to anterior and anteroventral margins (not shown, but similar to those along inner surface of overhang, Figure 87c).

Infold: Broad infold along anterior and ventral margins, and in caudal area, but inner margin not well defined in the latter (Figure 87c–e). Anterior infold with small bristle near valve midheight (Figure 87c). Infold of caudal area with 3 bristles (1 long, 2 short) along posterior concave edge, and 10 or 11 bristles anterior to edge (7 to 9 better defined than others and forming row close to posterior edge (Figure 87d,e)). 2 setal bristles on infold just dorsal to caudal area (Figure 87b,d,e).

Selvage: Broad undivided lamellar prolongation with smooth outer edge present along anterior and ventral margins; prolongation along outer edge of caudal area difficult to resolve but probably narrow.

Central Adductor Muscle Attachments (Figure 87f): Comprising 9–13 oval individual attachments.

Carapace Size: Sta 124-S: MNHN Os 459, holotype, length 0.81 mm, height 0.63 mm; USNM 193711, length 0.90 mm, height 0.71 mm. Sta 124-S: Paris, distorted specimen, length (measured while viewed dorsally) of left valve 0.82 mm. Sta 106-R: Paris, length 0.88 mm, height 0.69 mm (specimen left intact, may not be female).

First Antenna (Figure 88a): 1st joint with 5 or 6 minute distal medial spines forming row. 2nd joint with few spines along ventral and dorsal margins and on medial and lateral surfaces, with 1 dorsal bristle with few long proximal hairs and short distal spines. 3rd joint fused to 4th; 3rd joint with 2 long spinous bristles (1 dorsal; 1 longer, ventral). 4th joint with 2 long bristles (dorsal bristle with few indistinct spines; ventral bristle longer and with long marginal hairs). Sensory bristle of long 5th joint with 2 minute proximal filaments. 6th joint fused to 5th, with short medial bristle with few marginal hairs. 7th joint: a-bristle about 3 times length of bristle of 6th joint, with short marginal spines; b-bristle slightly shorter than a-bristle, with long terminal spine; c-bristle slightly longer than sensory bristle of 5th joint, with 2 minute marginal filaments and terminal spine. 8th joint: d- and e-bristles slightly shorter than c-bristle, bare with blunt tips; f-bristle shorter than c-bristle, with 2 minute proximal filaments and terminal spine; g-bristle shorter than c-bristle and longer than f-bristle, with 2 proximal filaments (length of proximal of these about twice diameter of bristle at base of filament; other about same diameter of bristle) and terminal spine.

Second Antenna: Protopodite bare (Figure 88b). Endopodite 1-jointed with 1 small proximal anterior bristle and medial spines forming rows; ventral margin either smoothly rounded (Figure 88b), or with very slight bulge. Exopodite: 1st joint with minute straight tubular medial bristle on terminal margin; bristle of 2nd joint long, with ventral spines (stout proximal spines becoming more slender distally along bristle) and natatory hairs near tip; bristles of joints 3–8 with stout proximal ventral spines and distal natatory hairs; 9th joint with 2 bristles (ventral bristle shorter and slenderer than bristle of 8th joint, with slender proximal spines and distal natatory hairs; dorsal bristle short and slender with few short hairs); joints 2–7 or 4–6 with few small spines along distal margins.

Mandible (Figure 88c–e): Coxale endite consisting of stout spine with few small marginal spines. Coxale with numerous slender spines along ventral margin. Basale: dorsal margin with unringed spine-like bristle at midlength, and 2 subterminal bristles (longer with faint rings, other unringed spine-like); ventral margin with 5 short bristles (2 proximal, 3 distal) with bases on medial side; lateral surface with 1 short bristle near ventral margin. Exopodite small with base inward from dorsal margin of basale, and with minute terminal bristle (not shown but similar to that of instar IV male, Figure 89c). 1st endopodial joint: medial surface with spines forming distal crescentic row, spines along distal margin in dorsal corner, and 2 spines near base of terminal ventral claw; lateral surface with spines forming rows (Figure 88c,d); dorsal margin with subterminal and terminal spines forming part of rows continuing on medial and lateral surfaces of joint; ventral margin with short spinous bristle at midlength and long terminal claw with 2 proximal prongs (1 dorsal and 1 ventral much longer and stouter) (Figure 88c,d); proximal dorsal edge of claw with minute perpendicular striations that may be internal. 2nd endopodial joint: lateral surface with spines forming rows including row along terminal edge; terminal lateral edge of joint extends slightly past terminal medial edge; dorsal margin with 2 single spine-like bristles near midlength; ventral margin with stout terminal claw about same width but longer than claw of 1st joint. 3rd endopodial joint with stout terminal claw, 1 small dorsal bristle, and 2 ventral bristles (1 small slender and 1 stout knife-like that could be interpreted to be a prong on terminal claw) (Figure 88e).

Maxilla (Figure 88f–i): Protopodite with dorsal fringe of long hairs. Coxale with 1 short bare dorsal bristle. Endite I with few minute proximal spines and 6 bristles (3 stout unringed, others ringed and either pectinate or spinous) (Figure 88f), endite II with long proximal spines and 4 bristles (2 stout unringed pectinate, others ringed and at least 1 spinous) (Figure 88h), endite III with 6 bristles (1 stout unringed pectinate, other ringed and either spinous or pectinate) (Figure 88f). Protopodite with thin flat diaphanous process (thumb-like in outline) near exopodite, and 1 short bristle adjacent to exopodite (Figure 88g). Exopodite with 2 bristles (shortest reaching past midlength of longest) (Figure 88g,i). Endopodite: 1st joint with slender spinous alpha- and beta-bristles with distal rings; 2nd joint with 2 slender a-bristles (posterior bristle longer), 1 slender c-bristle, and 5 stout pectinate terminal bristles.

Fifth Limb (Figure 88j,k): Epipodite with 36 bristles. Single endite with short bare bristle. 1st exopodial joint with 2 spinous bristles. Exopodial joints 2–5 not well defined from each other: joint 2 with 4 bristles (3 long terminal and 1 short proximal), all with short spines; inner lobe of 3rd joint with 3 bristles (1 short bare, 1 long bare, 1 long spinous); outer lobe of 3rd joint with 1 bristle with long terminal spine (this bristle missing on left limb of USNM 193711, Figure 88j); 4th and 5th joints with 2 long spinous bristles; 2nd to 3rd joints hirsute. Both endite and exopodial bristles ringed distally (not shown).

Sixth Limb (Figure 88l): Endite I with 3 short bristles. Endite II with 5 long spinous bristles (endite closer to end joint when limb compressed under cover slip than with cover slip absent as in Figure 88l, and could be interpreted to be part of end joint). End joint with 10 or 11 bristles (2 posterior bristles not greatly different from other long bristles on limb). Limb hirsute.

Seventh Limb (Figure 88m): Proximal group with 4 tapering bristles (2 on each side), each with 2 bells. Terminal group with 4 tapering bristles (2 on each side), each with 4 bells. Terminus with comb comprising 4 or 5 teeth (not all shown); side opposite comb bare. (Tapering bristles are juvenile character.)

Furca (Figure 88n): Each lamella with 6 claws: claws 1, 2, and 4 stout, primary, nonarticulated, and with narrowly rounded tips; claws 3, 5, and 6 short, slender, secondary, articulated, and with pointed tips. Claw 1 with 2 rows of teeth oriented posteriorly; claws 2–5 with single row; a few teeth on claws 1, 2, and 4 slightly stouter than others; no teeth observed on claw 6. Claws 1–5 with hairs or slender spines along anterior edges (not all shown). Long hairs forming medial row near base of claw 1, and also medially near anterior of right lamella. Several spines on edge of lamellae following claw 6 and along anterior edge of right lamella dorsal to claw 1. Right lamella anterior to left by about width of claw 1 at base (Figure 88n). A broad “apron” (with rows of minute spines) extending anteriorly just proximal to lamellae.

Bellonci Organ (Figure 88o): Elongate with 3 well-defined sutures near midlength and 4 additional incipient sutures marked by small marginal indentations (3 proximal, 1 distal); tip broadly rounded.

Eyes: Medial eye bare with brown pigment (Figure 88o). Lateral eye smaller than medial eye, with brown pigment and 5 amber-colored ommatidia (Figure 88o).

Upper Lip (Figure 87g): Somewhat triangular in lateral view, with short hairs.

Genitalia: None observed.

Anterior of Body: Sclerotized triangular process on each side of anterior of body just dorsal to protopodite of mandible (Figure 88a,o). (Process not equivalent to single anterior process at midwidth of anterior surface of body present on cypridinids.)

Posterior of Body (Figure 87h): Evenly rounded except for indentation near posterior end of Y-sclerite, bare.

Y-Sclerite (Figure 87h,i): Typical for subfamily.

Remarks: The key to developmental stages of Sarsiellidae presented in Kornicker (1981b:385) was used to identify the specimens described above as stage IV instars. The single- jointed endopodite of the 2nd antenna of the stage IV instars indicates that the specimens are females. It is likely that the 7th limb of the unknown adult female bears 6 terminal bristles rather than 4 as on the stage IV females. It is of interest that prongs (3) are present on the ventral claw of the 1st endopodial joint of the mandible of Dantya benthedi Kornicker, 1983c, in the Dantyinae; the same claw of C. radix bears 2 similar prongs; this is probably the result of convergence.

DESCRIPTION OF INSTAR IV MALE (Figure 89).—Carapace similar to that of instar IV female.

Carapace Size: USNM 193712, carapace distorted, length about 1.34 mm.

First Antenna (Figure 89a): 1st joint with few ventral spines. Limb otherwise similar to that of instar IV female.

Second Antenna: Protopodite similar to that of instar IV female. Endopodite 3-jointed (Figure 89b): 1st joint with 1 small proximal anterior bristle and medial spines forming rows; 2nd joint elongate bare; 3rd joint about same length as 2nd, with 2 proximal bristles and 2 smaller terminal bristles; all endopodial bristles ringed, bare, and with slender drawn-out tips. Exopodite: minute terminal medial bristles of 1st joint bent at right angle; limb otherwise similar to that of instar IV female.

Mandible (Figure 89c) and Maxilla: Similar to those of instar IV female.

Fifth and Sixth Limbs: Not examined in detail but appearing similar to those of instar IV female.

Seventh Limb (Figure 89d): Well developed. Proximal group with 2 tapered bristles (1 on each side of 8th segment counted from base of terminus), each with 3 bells. Terminal group with 4 untapered bristles (1 long and 1 short on each side), each with 5 bells. Terminus with small indentation at midwidth and 1 minute spine on one side of indentation and none on other side.

Furca: Main claws 1, 2, and 4 with blunt tips; furca otherwise similar to that of instar IV female.

Bellonci Organ (Figure 89e): Distal part broken off on USNM 193712 but remaining part suggests organ similar to that of instar IV female.

Eyes (Figure 89e), Upper Lip (Figure 89e), Anterior (Figure 89e) and Posterior of Body, and Y-Sclerite: Similar to those of instar IV female.

Genitalia: Obscured on USNM 193712, but not large if present.

COMPARISONS.—The digitate “bristles” on the outer surface of the shell of C. radix and the 2 prongs on the stout ventral claw of the 1st endopodial joint of the mandible are not present on previously described species of the genus.