Thaumatocypris echinata Mueller 1906

Thaumatocypris echinata Müller, 1906, 1100–2000 m, pelagic, Indian Ocean

Type 5. Nonreticulate, smooth.

Danielopolina phalanx, new species, lava tube, Canary Islands.

Thaumatoconcha caraionae Komicker and Sohn, 1976, 2707 m, South Atlantic.

Thaumatoconcha elongata Komicker and Sohn, 1976, 4124–4449 m, South Pacific.

Thaumatoconcha hessleri Komicker and Sohn, 1976, 619–717 m, South Atlantic.

Thaumatoconcha pix Komicker, 1992, 770–2900 m, off SE Australia and NE Tasmania.

Thaumatoconcha polythrix Komicker and Sohn, 1976, 2095–2223 m, North Atlantic.

Thaumatoconcha radiata Komicker and Sohn, 1976, 2440–4758 m, Antarctic, South Atlantic.

Thaumatoconcha sandersi Komicker and Sohn, 1976, 3658–3752 m, Antarctic.

Thaumatoconcha tuberculata Komicker and Sohn, 1976, 587–1493 m, South Atlantic.

Thaumatoconcha species A, Komicker and Sohn, 1976, 3035 m, Weddell Sea.

Thaumatocypris echinata Müller, 1906

Thaumatocypris echinata Müller, 1906:42, pl. 6: figs. 1–18; 1912:54 [listed].—Poulsen, 1969:7, figs. 1, 2.

HOLOTYPE.—Not designated.

TYPE-LOCALITY.—Valdivia station 190 V, 0°58′S, 99°43′E, southwest of Sumatra, 1100 m (Figure 9). The present location of the syntypes (6 specimens) is unknown.

OTHER LOCALITIES.—Indonesian area, 2°22′S, 126°58′E, about 2000 m (1 specimen) (Poulsen, 1969:12) (Figure 9).

MATERIAL.—We are unable to locate Müller’s syntypes. Through Dr. Torbin Wolff we obtained from the Zoological Museum of the University of Copenhagen the specimen described by Poulsen (1969:7).

DIAGNOSIS.—Each valve with upper and lower long anteroventral protuberances (Figure 14d); right valve with short posterodorsal tubercle (Figure 14c); surface smooth.

First antenna: First joint with 1 dorsal bristle, but without lateral bristle; 7th joint with 2 bristles, 1 ventral, 1 dorsal; 8th joint with 2 bristles.

Second antenna: Two-jointed; 1st endopodial joint with 3 bristles, 1 ventral, 2 dorsal.

Fifth limb: Second exopodial joint without terminal bristle on ventral margin; 3rd exopodial joint with 3 bristles.

Sixth limb: Process on dorsal corner of 1st exopodial joint with 1 bristle and 1 minute spine.

Rod-shaped organ: Minute, cone-shaped.

DESCRIPTION OF APPENDAGES.—First antenna: First joint with 1 dorsal bristle, but without lateral bristle; 2nd joint with 1 ventral and 1 dorsal bristle; 3rd and 4th joints fused except at sclerotized dorsal and ventral margins, especially the former; sclerotized dorsal margin of 3rd joint shorter than sclerotized dorsal margin of 4th joint; 3rd joint without bristles; 4th joint with 1 ventral bristle; 5th joint with 3 ventral bristles; 6th joint without bristles or with transparent ventral bristle; 7th joint with 1 ventral and 1 dorsal bristle; 8th joint with 2 bristles.

Second antenna: Protopodite without a bristle. Endopodite 2-jointed: 1st joint with 1 dorsal and 2 ventral bristles; 2nd joint with 1 lateral and 4 terminal bristles. Exopodite 9-jointed: 1st joint without a bristle, 2nd to 8th joints with natatory setae; 9th joint with 2 bristles.

Mandible: Basale: posterior margin with 2 bristles; anterior margin with 2 or 3 bristles; lateral side with 5 to 7 bristles; knife-like spine may not be present; medial side with 2 bristles. Endopodite: 1st joint with 1 dorsal bristle; 2nd joint with 3 or 4 ventral and 2 or 3 dorsal bristles; 3rd joint with 6 bristles.

Maxilla: Endite I with 8 or 9 bristles; endites II and III with total of 15 bristles. Basale with either 1 bristle or without bristles on dorsal margin and with 1 or 2 bristles on ventral margin. Endopodite: 1st joint with 4 or 5 anterior bristles and 2 posterior bristles; 2nd joint with 6 bristles.

Fifth limb: Epipodial appendage with 13 bristles; prodopodite and endopodite with 17 bristles. Exopodite: 1st joint with 1 dorsal bristle and 8 ventral bristles; ventral margin of 2nd joint with 2 midbristles; 3rd joint with 3 subequal bristles.

Sixth limb: Epipodial appendage with about 12 bristles; prodopodite with 4 bristles. Exopodite: process on dorsal corner of 1st joint with 1 bristle and 1 minute spine; 1st joint with 4 additional bristles; combined 2nd and 3rd joints with 1 dorsal bristle and 2 ventral midbristles; 4th joint with 3 subequal bristles.

Seventh limb: Small with 2 long bristles.

Rod-shaped organ: Absent, or represented by short cone.

Posterior of body: Single process present proximal to furcal lamellae; posterior wrinkled along posterior margin dorsal to process.

Lips: Müller’s illustration of the upper and lower lips of this species (1906, pl. 6: fig. 3) indicates that the lips are similar to those of Danielopolina and Thaumatoconcha.

DISCUSSION OF CENTRAL ADDUCTOR MUSCLE ATTACHMENT SCAR.—In his description, Müller (1906: 43) stated that the closing muscle attachments are unclear. The muscle-scars of one of the specimens that he illustrated (1906, pl. 6: fig. 1) consist of 1 large ovoid scar anterior to 3 smaller ovoid scars forming an oblique row. Poulsen (1969) did not describe or illustrate the muscle scars of this species. We restudied Poulsen’s specimen for the purpose of determining the muscle scar pattern on T. echinata. Unfortunately, the muscles are partly ripped from the shell of Poulsen’s specimen so that we could not determine the precise number and the distribution of individual scars. Two adjacent muscle fascicles adhering to the left valve are interpreted to be in position (Figure 15). The position of these two fascicles suggests that all the fascicles are oriented to form a radial group. The two adjacent muscle ends are similar to some of the muscle ends illustrated by Danielopol (1972, fig. B) for Thaumatocypris orghidani Danielopol, 1972 (= Danielopolina), and also to those we illustrate herein for the male of Thaumatoconcha sandersi, new species (Figure 59b). Unfortunately, because of the poor condition of Poulsen’s specimen we were unable to conclude whether or not all the fascicles were radially arranged. Pending study of additional material, we believe that the muscle-scar pattern of the type-species is radial and not like the pattern illustrated by Müller (1906, pl. 6: fig. 1).

COMPARISONS.—See Table 13.

Thaumatoconcha, new genus

TYPE-SPECIES.—Thaumatoconcha radiata, new species.

ETYMOLOGY.—Name derived from a combination of the Greek thauma (wonder, marvel) + konche (shell).

caraionae, new species • polythrix, new species sandersi, new species

elongata, new species punctata, new species tuberculata, new species

hessleri, new species radiata, new species species A

This genus contains 8 species, all new and one additional taxon in open nomenclature: T. radiata, T. sandersi, T. hessleri, T. tuberculata, T. caraionae, T. elongata, T. polythrix, T. punctata, and Thaumatoconcha species A.

DISTRIBUTION.—Atlantic Ocean, 32°N to 73°S; Pacific Ocean, 7°S to 70°S (Figure 9).

HABITAT.—Benthic.

DIAGNOSIS.—Carapace with ridges restricted to anteroventral surface of carapace; short anteroventral protuberances crudely reticulated; without posterodorsal tubercles except T. tuberculata; 1st antenna with 2 bristles on 1st joint; rod-shaped organ well developed. Surface smooth or coarsely to finely punctate, some species with small pustules visible with SEM; anteroventral surface with 1 to 11 thin ridges parallel to valve margin; cross-ridges on and near anteroventral protuberances; only 1 species, T. tuberculata, with minute posterodorsal tubercule on right valve located posterior to similar tubercle on left valve. Dimensions of carapaces are compared in Figures 16, 17.

caraionae, new species •polythrix, new species sandersi, new species

elongata, new species radiata, new species tuberculata, new species

First antenna: 1st joint with 2 bristles, 1 dorsal, 1 lateral; 7th joint with 3 bristles, 2 ventral, 1 dorsal; 8th joint with 3 bristles.

Second antenna: First endopodial joint with 3 bristles, 1 ventral, 2 dorsal.

Fifth limb: 2nd exopodial joint without terminal bristle on ventral margin; 3rd exopodial joint with 2 (rarely 3) bristles.

Sixth limb: Process on dorsal corner of 1st exopodial joint with 3 bristles; 4th exopodial joint with 2 bristles.

Rod-shaped organ: Elongate with rounded or pointed tip.

DESCRIPTION OF APPENDAGES OF ADULT FEMALE.—First antenna: First joint with 1 dorsal and 1 lateral bristle; 2nd joint with 1 dorsal and 1 ventral bristle; 3rd and 4th joints fused except at sclerotized dorsal and ventral margins, especially the former; segment of dorsal margin of 3rd joint longer than that of 4th joint except for T. hessleri and Thaumatoconcha species A; 3rd and 4th joints usually without bristles, but rarely with a ventral bristle; 5th joint with 2 or 3 ventral bristles; 7th joint with 3 bristles, 2 ventral, 1 dorsal; 8th joint with 3 bristles.

Second antenna: Protopodite without bristles. Endopodite 3-jointed: 1st joint with 3 bristles, 1 ventral, 2 dorsal; 2nd joint with 5 bristles, 1 ventral, 4 terminal; 3rd joint with 2 or 3 bristles. Exopodite with 8 joints, except T. radiata, T. punctata, and T. tuberculata which have 9: 1st joint divided into long proximal and short distal parts, without medial bristle; joints 2 to 8 with natatory bristles; 9th joint with 2 bristles, except T. radiata which has either 2 or 3.

Mandible: Proximal flat tooth of distal set on coxale endite with 1 large lateral cusp and 6 or 7 small pointed cusps. Basale: anterior margin of endite with 1 bristle; posterior margin with 3, rarely 2, proximal bristles, and usual blunt distal bristle; lateral side with flat knife-like process and 5, rarely 4, bristles. Endopodite: dorsal margin of 1st joint with 1 bristle, except T. polythrix which has 5 or 6 bristles; ventral margin of 2nd joint with 3 or 4 bristles; dorsal margin of 2nd joint with 2 bristles, except T. polythrix which has 3 bristles; 3rd joint with 6 or 7 bristles: 3 lateral (middle of these claw-like and longer than others), 3 or 4 medial (1 of these on or near ventral margin).

Maxilla: Endite I with 9–12 bristles; endite II with 8–11 bristles; endite III with 6–8 bristles. Basale with 2 bristles, 1 ventral, 1 dorsal. Endopodite: anterior margin of 1st joint with 5 or 6 bristles, except T. polythrix which has 7; posterior margin with 2 or 3 bristles; 2nd joint with 8 or 9 bristles, 1 of these is stout and claw-like, another, with base on posterior margin, is long and stout with short marginal spines.

Fifth limb: Epipodial appendage with 14 bristles arranged in 3 groups—5, 5, and 4. Protopodite and endopodite with 15–23 bristles. Exopodite: dorsal margin of 1st joint with usual single bristle; ventral margin of 1st joint with 6–10 bristles; ventral margin of 2nd joint with 2 or 3 midbristles; 3rd joint with 1 long claw-like bristle and 1 shorter bristle.

Sixth limb: Epipodial appendage with 15 plumose bristles; protopodite with 4 bristles, except T. polythrix which has 5 or more. Exopodite: process on dorsal corner of 1st joint with 3 bristles; 1st joint with 3–6 additional bristles, except T. polythrix which may have as many as 8; 4th joint with 1 long claw-like bristle and 1 shorter bristle.

Seventh limb: Small with 2 long spinous bristles.

Furca: Each lamella with 2 long anterior claws separated by suture from lamella, followed by 6 short claws joined to lamella; 1 small process oriented posteriorly present following claws.

Rod-shaped organ: Elongate, 1-jointed or weakly 2-jointed with tapered or rounded tip.

Posterior of body: Single process present proximal to furcal lamellae; posterior margin distinctly divided into narrow segments.

Lips: Upper lip: proximal part with triangular sclerotized lateral process on each side oriented anteriorly; distal part with 4 spine-like processes at tip oriented posteriorly; T. punctata with additional small processes on distal part of lip (Figure 13d,i).

DESCRIPTION OF ADULT MALE.—Similar in shape and ornamentation to that of female but slightly smaller.

First antenna: Joints 1, 2, and 3 similar to those of female, except 3rd and 4th joints separated by well-defined suture on some species (T. radiata, T. elongata, T. polythrix, T. sandersi); 4th joint with 2 ventral bristles; 5th joint with 3 ventral bristles, the longer of these with short marginal hairs (sensory bristle); 6th to 8th joints similar to those of female.

Second antenna: Protopodite and exopodite similar to those of female. Endopodite: 1st and 2nd joints similar to those of female; 3rd joint with large curved sclerotized hook-like process with 2 minute spines at tip; surface of hook pustulose near tip; base of process either on medial side of joint or terminal.

Mandible, maxilla, 5th limb, 6th limb, 7th limb, furca, rod-shaped organ, posterior, lips: Similar to those of female, but with few differences in numbers of bristles on mandible, 5th and 6th limbs that could be attributed to interspecific variability (Table 13). An exception might be the 1st joint of the exopodite of the 6th limb of T. polythrix with 5 or 6 bristles compared to 8 on female.

Copulatory organ (Figure 18): Single organ consisting of 2 parts present on left side of body: anterior part elongate with either a recurved process, T. sandersi (Figure 18a–c), a single long tooth-like process, T. caraionae (Figure 18g–i), T. elongata (Figure 18n–p), T. polythrix (Figure 18q–s), a long tooth-like process with a minute tooth at its base, T. tuberculata (Figure 18j–m), or about 8 teeth, T. radiata (Figure 18d–f); posterior part shorter than anterior part, tapered, styliform with 3 hair-like bristles at tip.

COMPARISONS.—See Table 13.

SHELL STRUCTURE.—An outer layer of shell flaked off many specimens during the freeze-drying process used prior to SEM micrography (Figures 22a,c,d; 23a,b,d). We observed that when the outer layer of shell is present, details of the central muscle attachment scar are not visible in reflected light or in SEM micrographs when the shell is viewed from the outside. The scar is visible when the outer layer has flaked off (Figure 23b). Hemispherical nodules similar to those described by Sohn and Kornicker (1969:101) from Vargula hilgendorfii (Müller, 1890) were observed on a few carapaces of Thaumatoconcha radiata.