Skogsbergia squamosa (Mueller 1894)

Skogsbergia squamosa (Müller, 1894)

Cypridina squamosa Müller, 1894:207, pl. 2, figs. 3, 6, 7, 21, 28–32; 1912:10 [key], 12 [diagnosis].—Rome, 1942:8 [listed]; 1965:4, table 1 [listed].—Puri, 1963:2 [listed].

Cypridina (Vargula) squamosa.—Skogsbcrg, 1920:75, 247 [discussion].

Skogsbergia squamosa.—Poulsen, 1962:162 [discussion], 163 [distribution], 164 [key].

Not Cypridina squamosa.—Tressler, 1949:335, fig. 21 [probably Skogsbergia lerneri (Kornicker, 1958); see p. 4].

Not Cypridina squamosa lerneri.—Kornicker, 1959:229, figs. 47a–b, 48a–d, 49a–e [ = Skogsbergia lerneri (Kornicker, 1958); see p. 4],

Not Cypridina (?) squamosa.—Brady, 1897:90, pl. 16, figs. 10–12 [species dubium],

LECTOTYPE (designated herein).—One female with eggs in ovaries (ZMB 9151). Carapace, upper lip, 1st antenna preserved in alcohol, remaining appendages on 1 slide; collected by G. W. Müller.

TYPE-LOCALITY.—Gulf of Naples.

MATERIAL.—Pre-adult with eggs in ovaries (ZMB 9151). Carapace, upper lip, and one 1st antenna preserved in alcohol; remaining appendages on slides (lectotype). Adult without carapace from the Zoological Institute of Greifswald (GMZ 24999); dissected specimen now on slides. The description given below is based on this specimen and the lectotype. The specimen was in a vial, which also contained a juvenile without carapace and four separated valves. All specimens collected by G. W. Müller.

DISTRIBUTION.—Mediterranean: Gulf of Naples; also reported off Monaco (Rome, 1942, 1965).

Brady and Norman (1896:650) referred specimens collected in the Gulf of Naples to Cypridina mediterranea Costa, 1845. They recognized two forms “typica” and “Var. b,” and stated that after their description was written, Müller (1894) described variety b under the name Cypridina squamosa. Later, Müller (1912:12) included Brady and Norman’s variety b in his synonomy of C. squamosa, but questioned it. As Brady and Norman did not describe the appendages, and illustrated (1896, pl. 54: figs. 3, 4) only a lateral and dorsal view of the carapace, it is not possible to refer, with certainty, their variety b, to any particular species.

A specimen designated “Cypridina (?) squamosa” by Brady (1897:90, pl. 16: figs. 10–12) does not have the 2nd and 3rd claws of the furca united with the lamella. Brady (1897:90) recognized that he knew too little about the soft parts of the species to be certain about its generic position. He apparently named the species prior to being aware of Müller’s 1894 name for the Gulf of Naples’ species, and did not wish to change the name in manuscript. Müller (1912:52) correctly listed this species under “Cypridinidarum genera dubia et species dubiae.”

Skogsberg (1920:247) included Cypridina squamosa Müller in a list of species to be included in his subgenus Vargula.

Tressler (1949:335, fig. 21) identified specimens from Florida as Cypridina squamosa Müller. I have examined the caudal furca on one of Tressler’s specimens (USNM 88862) and find only claw 2 continuous with the lamella, and, therefore, conclude that Tressler’s specimens are not conspecific with S. squamosa.

Kornicker (1958:229, figs. 47a–b; 48a–d; 49a–e) identified specimens from the Bahamas as Cypridina squamosa lerneri. These have only claw 2 of the furca continuous with the lamella. I believe that this difference warrents raising the subspecies to specific rank. After having examined a paratype, I conclude that the species C. lerneri should be referred to the genus Skogsbergia.

Poulsen (1962:162) referred C. squamosa to Skogsbergia.

DESCRIPTION OF FEMALE.—Carapace oval in lateral view with greatest height posterior to middle; inferior tip of rostrum pointed; inner margin of incisur rounded (Figure 1a,d); caudal process narrow extending to middle of posterior margin (Figure 1g,h).

Ornamentation: Surface with scalelike reticulations (Figure 1c) posterior margin of scales convex; shell surface appearing smooth under low magnification; valves translucent with lateral eyes and muscle scars visible in external view.

Infold (Figure 1e,f): Infold broad and vestibule deep along anterior shell margin and in front of caudal process; infold narrow and vestibule shallow along ventral margin; infold above incisur with about 16 bristles, below incisur and along ventral margin with about 25 bristles in row.

Hinge: Sclerotized inner ridge of caudal process of left value with knob at dorsal end which may interlock with socket on right valve.

Marginal pore canals: Numerous along free margins. Similarly oriented canals also present along sclerotized inner bar of caudal process.

Central muscle scars (Figure 1b): Consisting of about 15 individual scars; of these, 3 elongate anterior scars slope downward posteriorly, whereas, posterior scars trend downward anteriorly producing a roughly chevron-type muscle scar.

Size: (N-1 instar), length 2.61 mm, height 1.69 mm. Müller (1894:207) gave the lengths of 2 females as 3.3 mm, and of 2 males as 2.6 mm.

Sexual dimorphism: According to Müller (1894:207), the shell of the male is similar to that of the female but smaller.

First antenna (Figure 1i): 3rd joint with dorsal margin longer than ventral, dorsal bristle proximal to middle, and ventral bristle distal to middle; 4th joint with 2 bare terminal bristles, 1 ventral, 1 dorsal; 5th joint separated from 6th by distinct suture; sensory bristle of 5th joint with 8 long proximal and 3 or 4 short distal filaments; 6th joint with bare lateral bristle. 7th joint: a-bristle bare, b-bristle with about 3 filaments, c-bristle with short proximal filaments and 1 long and 1 short distal filament. 8th joint with 4 bristles: d- and e-bristles bare, f- and g-bristles with filaments.

Second antenna (Figure 1j,k): Protopodite with medial bristle with short marginal spines. Endopodite 2-jointed: 1st joint with 5 bristles consisting of a proximal group with 3 short bare bristles and 1 long bristle with marginal spines and a distal long ventral bristle with few marginal spines; 2nd joint with long, faintly annulate, terminal bristle (2nd joint could be interpreted as being bulbous base of bristle). Exopodite: length of 2nd joint equal to combined lengths of joints 3–5; bristle of 2nd joint without curly hairs proximally and with about 14 ventral spines; joints 3–9 with basal spines, spines longer on distal joints; 9th joint with 4 bristles, 3 long and 1 short; bristles on joints 3–9 with natatory hairs.

Mandible (Figure 1l,m): Coxale endite spinous. Basale with 3 dorsal and 6 ventral bristles: 1 long spinous and 2 short bare a-bristles, 1 long c-bristle, and 1 long spinous and 1 short bare d-bristle. Exopodite with acute tip and 2 ventral bristles, proximal bristle longer of two. Endopodite: 1st joint with 2 long and 2 short distoventral bristles; 2nd joint with 3–4 ventral spinelike bristles, 1-2 distal to middle and 2 proximal to terminal tooth, and about 19 dorsal bristles; end-joint with 3 claws and 4 bristles. Ventral margin of basale on N-1 with 8 bristles: 1 long and 2 short a-bristles, 1 short b-bristle close to a-bristles, 1 short and 1 long c-bristle, and 1 short bare and 1 long spinous d-bristle; ventral margin of 2nd joint of endopodite with 2 spinelike bristles distal to middle and 2 proximal to the reduced terminal tooth.

Maxilla (Figure 1n,o): Precoxale with fringed marginal epipodial appendage; coxale with plumose bristle on anterior margin; lst-3rd endites hirsute, 1st with about 11 bristles, 2nd with about 7, 3rd with 7 distal and 1 proximal bristle; basale with bare ventral bristle (missing on some appendages); 1st joint of endopodite with 2 bare α-bristles and 3 β-bristles; cutting edge on distal posterior corner of 1st joint consisting of ridge with 3 arcs; end joint of endopodite short, with about 11 bristles; medial surface with clusters of fine hairs; exopodite hirsute along posterior margin, with 1 plumose posterior bristle and 2 terminal bristles, 1 bare, 1 plumose.

Fifth limb (Figure 1p): Epipodial appendage with 53–55 plumose bristles; endites I–III each with about 5 bristles. Exopodite: 1st joint with 6 curved teeth in row followed by conical tooth; 2nd joint with 4 curved clawlike teeth, 8 stout curved bare bristles, and 3 plumose bristles; 3rd joint hirsute, inner lobe with 2 distal and 1 proximal bristle, outer lobe with 2 distal bristles; 4th and 5th joints fused, hirsute with total of 4 bristles distally.

Sixth limb (Figure 2a): Epipodial appendage with 4 bare bristles. End joint with 15 bristles, the 2 posterior bristles longer than others. First endite with 1 long and 2 short bristles; 2nd endite with 2 long and 2 short bristles; 3rd endite with 3 long and 1 short bristle; 4th endite with 3 long and 2 short bristles. End joint with clusters of spines on lateral surface and longer spines along ventral margin; medial surface with clusters of long spines.

Seventh limb (Figure 2b): Adult with 13 proximal and 15 distal bristles; comb with about 20 square-tipped teeth opposite short blunt cylindrical tooth. N-1 with 14 proximal and 14 distal bristles and only about 14 teeth in comb. All bristles with 2–6 distal bells and without marginal spines.

Furca (Figure 2c,d): Each lamella with 7 claws in adult , 6 in N-1 ; 2nd and 3rd claws united with lamella; 4th claw more slender than 5th; ventral margin and lateral surface of each lamella proximal to claws bearing clusters of short spines; proximal claws on right lamella slightly longer than on left; claws 1–5 with lateral and medial spines in row along concave margin, claws 6–7 with single row; claws 1–2 with minute spines distally along convex margin; claw 1 with large medial spines distally; several small spines present along anterior margin of each lamella.

Brush-shaped organ (Figure 2e): Short lobe bearing 8 bare annulate bristles situated above genital organs and behind each 7th limb (observed on both adult and N-1 ).

Genitalia (Figure 2c): Bilobed (attached to one of the lobes of the N-1 is what appears to be a rhizopod similar to the genus Centropyxis.)

Eyes (Figure 2g): Lateral eyes with 29–34 ommatidia, all but few divided; medial eye about half diameter of lateral eye.

Rod-shaped organ (Figure 2f): Short, pearshaped with concentric ridges distally and terminal node. Conical projection present between organ and upper lip.

Upper lip (Figure 2f): Anterior lobe undivided and with glandular openings; posterior lobe divided, hirsute; lateral lobes small, hirsute. Lower lip helmet-shaped, hirsute.

Eggs (Figure 2h): Cluster of 13 round eggs present in each ovary of N-1 instar.