Gephyrocrinus messingi Roux & Lambert, 2011, n. sp.

• Main Authors: Roux, Michel, Lambert, Philip
• Format: Text
• Language: unknown
• Published: Zenodo 2011
• Subjects: Biodiversity; Taxonomy; Animalia; Echinodermata; Crinoidea; Hyocrinida; Hyocrinidae; Gephyrocrinus; Gephyrocrinus messingi; San Juan; Pacific; Queen Charlotte; Rodriguez; Anvers; Pawson; Sorokina; Middle Arm; Three Arms; Cape Scott; Antarc*; Antarctique*
• Online Access: https://dx.doi.org/10.5281/zenodo.6187428; https://zenodo.org/record/6187428

Gephyrocrinus messingi n. sp. Etymology. This species is kindly dedicated to Charles Garrett Messing of Nova Southeastern University (Florida) who provided the specimens collected during MBARI cruises. Material examined. The specimen trawled in October 2006 off Cape Scott (Vancouver Island), Queen Charlotte Sound, is designated as the holotype, catalogue number RBCM 007-00004-011. Four other specimens were collected during MBARI cruises off California using the ROV “Tiburon”: (1) two specimens in October 2003 on the basaltic rocky substrate of Rodriguez Seamount, registration numbers in SIO E 4426; (2) two others in 2004 on hard ground of San Juan slope, registration numbers in SIO E 4427. Table 1 gives detailed locations of specimens. Diagnosis. A species of the genus Gephyrocrinus with a normal proximal arm pattern of 1 + 2 3 4 5 + 6 7 + 8 9 + 10 (80 %) and first pinnule on Br 4; beyond Br 4, free brachials more frequently at Br 13 (52 %), Br 16 (64 %) and Br 19 (64 %); three or more successive muscular articulations appearing rarely after Br 15, more frequently after Br 19; pattern very variable beyond Br 25, from series of more than 15 successive muscular articulations (sometime reaching the arm tip) to exceptionally long series of successive brachial pairs. Brachial constriction between two muscular articulations more marked in juveniles than in adults. Base of genital pinnules with numerous small polygonal lateral plates not in rows; shape (frequently irregularly sub-quadrangular) and size of lateral plates variable on two sides of genital inflation, frequently present in middle pinnule at least on one side; cover plates rounded to sharply lanceolate. Tegmen with a verrucose ornamentation, variously inflated, frequently globular, relative inter-ray width (Wr/Wb) usually more than 2.0, anal sac bottle-shaped slightly shorterer or taller than oral cone, orals smooth with rounded top. Conical aboral cup with a conspicuous ornamentation of radial ribs and transverse ridges, basal fused, aboral border of basal ring flanged. Columnal symplexies with 6–7 crenular units of 1–2 short crenulae (up to 3 in largest specimens). TABLE 2. Variation of main morphological characters in the type series of Gephyrocrinus messingi n. sp. La: arm length; Lp: pinnule length; Np: number of pinnules on each arm side; Wb: Br 1 width; Wr: radial width; Hc: aboral cup height; Hr: radial height; Dc: uppermost diameter of aboral cup; Drb: diameter at radial-basal sutures; Dp: proximalmost stalk diameter; Dm: minimum stalk diameter. Values in mm except for Np. Dp and Dm are used as growth index (in yellow). TABLE 3. Variation of main morphological ratios through ontogeny in the type series of Gephyrocrinus messingi n. sp. Abbreviations and growth index as in Table 2. Specimen Lp/La Hc/Dc Hr/Hc Hr/Wr Wr/ Wb Dc/Drb Drb/Dp Dp/Dm T 662 -B 0.59 0.83 0.57 1.1 2.00– 2.25 2.6 1.23 1.7 T 662 -A 0.43 1.01 0.54 1.2 2.37–2.50 1.6 2.0> 1.5 Holotype - 0.99 0.59 0.98 1.93–2.08 1.64 2.30> 1.3 T 629 - 1 0.29–0.32 0.88 0.62 0.95 –1.0 2.11–2.21 1.72 2.37 1.3 T 629 - 2 0.31–0.40 0.89 0.63 0.93 2.03–2.27 1.56 2.33 1.45 Description. The main morphological measurements and arm patterns observed in the crown are given in Tables 2, 3 and 4, respectively. HOLOTYPE: Specimen with proximal stalk and nearly complete crown (Fig. 2). Arms moderately graceful (Wr/ Wb about 2.1), rolled up near distal end, bearing about 30 well-differentiated pinnules on each side or slightly more (maximum 27 observed before broken arm end) with a wide space between successive pinnules especially in proximal part of arms (Fig. 2). FIGURE 3. Gephyrocrinus messingi n. sp. , arm and base of pinnule. a to c: holotype; paratype (T 629 -A 4 - 2); a–b: lateral view of pinnule base; c: inflated and mutiplated adoral architecture of arm; d: same arm part without inflation; a-c-d: light microscopy; b: SEM view; fcv: festooned cover plates in a gathered arrangement, pv: pavement of polygonal lateral plates. FIGURE 4. Gephyrocrinus messingi n. sp. , brachial and pinnular ossicles of the holotype (SEM micrographs). a: hyposynostosial brachial, proximal facet (synarthry); b to e: episynostosial brachials, b: proximal facet (flat synostosis), c: distal facet (synarthry), d: ventral-distal view, e: lateral view with pinnule socket; f: pinnular beyond genital inflation. San Juan I, T 622 -B (Dp = 1.3 mm) 1 + 2 3 4 5 6 + 7 8 + 9 10 11 + 12 13 1 + 2 3 4 5 + 6 7 8 + 9 10 11 + 12 13 14 + 15 16 17 18 19 20 + 21 22 23 1 + 2 3 4 5 + 6 7 + 8 9 10 + 11 12 13 + 14 15 16 + 17 18 19 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 12 + 13 14 1 + 2 3 4 5 + 6 7 + 8 9 10 + 11 12 13 + 14 15 16 17 + 18 19 20 + 21 22 23 + 24 25 San Juan I, T 622 -A (Dp = 2.2 mm) 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 12 + 13 14 15 + 16 17 18 + 19 20 21 + 22 23 24 25 26 + 27 28 29 30 31 32 33 + 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 + 14 15 16 + 17 18 + 19 20 21 + 22 23 24 + 25 26 27 + 28 29 30 31 32 + 33 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 + 14 15 16 + 17 18 19 + 20 21 22 + 23 24 25 26 27 + 28 29 30 31 32 33 + 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 12 + 13 14 15 + 16 17 18 + 19 20 21 + 22 23 24 25 + 26 27 28 29 30 + 31 32 33 34 Off Vancouver Island, Holotype (Dp = 2.3 mm) 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 24 + 25 26 27 + 28 29 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 24 25 + 26 27 28 29 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 21 + 22 23 24 25 26 27 + 28 29 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 24 + 25 26 27 28 29 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 18 + 19 20 21 22 23 + 24 25 26 27 28 29 30 31 32 33 34 Rodriguez Seamount, T 629 - 1 (Dp = 2.4 mm) 1 + 2 3 4 5 + 6 7 + 8 9 10 + 11 12 + 13 14 + 15 16 17 + 18 19 20 + 21 22 23 + 24 25 26 27 28 + 29 30 3132 33 + 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 + 14 15 16 + 17 18 19 + 20 21 22 23 + 24 25 26 27 + 28 29 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 12 + 13 14 15 + 16 17 18 + 19 20 21 + 22 23 24 25 26 + 27 28 29 30 31 32 + 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 12 + 13 14 15 + 16 17 18 + 19 20 21 + 22 23 24 + 25 26 27 28 29 + 30 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 + 24 25 26 27 28 + 29 30 31 32 33 + Rodriguez Seamount, T 629 - 2 (Dp = 2.7 mm) 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 21 + 22 23 24 25 26 27 + 28 29 30 31 + 32 33 + 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 24 25 26 27 + 28 29 + 30 31 32 33 + 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 + 21 22 23 24 25 26 27 + 28 29 30 31 32 33 + 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 + 14 15 16 17 + 18 19 20 21 22 23 24 + 25 26 27 28 29 30 + 31 32 33 34 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15 16 17 + 18 19 20 21 22 + 23 24 25 26 27 28 29 + 30 31 32 33 34 Tegmen easily visible interradially between narrow proximal brachials. Br 2 and Br 3 as wide as Br 1; arm axis becoming progressively narrower distally. Free brachials and brachial pairs slightly constricted midway between their proximal and distal muscular articulations; proximal brachial with moderate lateral wings and thorns near muscular articulations. Proximal arm pattern very regular with 1 + 2 3 4 5 + 6 7 + 8 9 + 10 11 + 12 13 14 + 15, and first pinnule on Br 4 in five arms (Table 4); pattern of middle arm more variable; three successive muscular articulations appearing between Br 16 and Br 23; series of 18 or more successive muscular articulations beginning between Br 25 and Br 29; distal arm with a few brachial pairs irregularly placed. Maximum length of pinnules 30 mm on P 2 but probably longer in middle arm. Pinnule base with polygonal lateral plates not in rows and with curved cover plates in a gathered arrangement (Fig. 3 a, b); from proximal to distal part, largest lateral plates flat and irregularly rectangular on each side not united by stereom bridge; cover plates poorly preserved with variable shape, usually rounded or lanceolate, sharper distally. Adoral face of arms and proximal pinnules strongly inflated (Figs. 3 a, c), the inflation decreasing distally. Brachial and pinnule articulations (Fig. 4) with the main classical features known in hyocrinids (adoral ligament area without galleried stereom, flat synostoses without stereom differentiation); adoral groove of brachials widely open between deep concave insertion area of inner ligaments and muscles (Fig. 4 a, c, d); pinnule socket oblique and in relatively lateral position midway from brachial facets (Fig. 4 e); pinnulars with the two lateral sides quite equal (Fig. 4 f). Globular tegmen regularly inflated up to Br 8, sticking to proximal arm; first pinnule remaining free. About 25 tegminal plates per interradius with verrucose ornamentation of irregular bumps or knobs (Figs. 3 a, 5 a). Height of tegmen at oral cone 8.4 mm. Oral cone shorter than anal sac; orals of moderate size with smooth globular top; cover plates in regular rows converging to oral cone (Fig. 5 d); top of anal sac in relatively central on tegmen. Aboral cup conical, slightly bowl-shaped, strongly ornamented by conspicuous coarse ribs prolonging arm axis and subdivided in variable parallel ridges especially near basal-radial suture; 5 to 7 small perpendicular ridges on interradial surface (Fig. 6 a). Basal fused; aboral border of basal ring flanged by 7 rounded knobs. Height of aboral cup 8.6 mm; height of basal ring 3.5 mm; diameter at base of basal ring 2.6 mm; diameter at base of radial ring 5.3 mm; diameter at top of radial ring 8.7 mm; interray spaces wide (Wr/Wb 2.15 + 0.22). Length of preserved stalk 59.3 mm; proximalmost diameter (Dp) 2.3 mm, decreasing to 1.78 mm at distal end of preserved stalk with columnal height 0.77 mm (H/D 0.43); stalk broken before minimum diameter. Proximal stalk very heterometric (thickness and diameter variable) with seven longitudinal rows of knobs aligned with knobs on base of basal ring (Fig. 6 a). Proximal symplexies heptagonal with 7 short crenular units of 1 or 2 crenulae and a conspicuous claustrum (Fig. 7 a), becoming circular and with 1 crenula per crenular unit in distal part of preserved stalk. PARATYPES FROM RODRIGUEZ SEAMOUNT (SIO E 4426): Two relatively large and complete specimens, distal stalk missing. Arms and pinnules gracile and flexible, rolled up at their distal end (Fig. 8). Proximal arm pattern always 1 + 2 3 4 5 + 6 7 + 8 and first pinnule on Br 4; middle and distal arm pattern more variable than in holotype (Table 4). Flat irregular lateral plates on each pinnule side (Figs. 9 a, b); middle and distal parts of pinnules with smaller lateral plates at least on one side, or cover plates only; shape of cover plates usually triangular with narrow or sharp end, sometimes lanceolate and more rounded (Figs. 9 b to d). H-shaped plates between the two sides absent, causing frequent collapse of adoral architecture. FIGURE 5. Gephyrocrinus messingi n. sp. , inflated tegmen. a and d: strongly inflated holotype; b: paratype T 629 -A 4 - 2; c, e and f: paratype T 629 -A 4 - 1; a to c: lateral views of anal inter-ray showing conspicuous anal sac in b and c; d to e: oral cones; f: detail of oral ring. FIGURE 6. Gephyrocrinus messingi n. sp. , variation in aboral cup and proximalmost stalk. a: holotype; b: paratype T 629 -A 4 - 1; c–d: paratype T 629 -A 4 - 2. Spherical inflated tegmen; inflation not extending onto arms and pinnules. Oral cone slightly taller than anal sac; orals with rounded, smooth top and base bearing several knobs each (Figs. 5 e, f). Anal sac adjacent to outer margin of tegmen, easily observed and with a group of about eight apical spines (Figs. 5 b, c). Regular conical aboral cup with the same general pattern of ornamentation as in the holotype but with variable development of transverse ridges (Figs. 6 b to d). FIGURE 7. Gephyrocrinus messingi n. sp. , columnal articulations of mature specimens (SEM micrographs). a: proximal symplexy in holotype; b–c: proximal mesistele symplexy in paratype T 662 -A; d-e: paratype T 629 -A 4 - 1, d: middle mesistele symplexy, e–f: distal columnal of preserved stalk with development of syzygial crenularium beginning on outer facet; arrow indicates claustrum. Specimen T 629 -A 4 - 1: Maximum arm length 98 mm; two arms longer than the others; up to 32 pinnules on each arm side; maximum pinnule length 31 mm between Br 26 and 30. Beyond Br 4, first free brachial from Br 9 to Br 15, maximum number of successive muscular articulations usually 5, rarely 11 or 13 distally. Tegmen moderately inflated, not attached to proximal arm, and with a coarse vermiculate ornamentation (Fig. 5 c). Top of anal sac at 7.2 mm above upper radial border; tegmen height at oral cone 8.5 mm. Diameter at base of basal ring 2.8 mm; diameter at base of radial ring 5.7 mm; diameter at top of radial ring 9.8 mm; interray width (Wr/Wb) 2.16 + 0.05. Aboral cup ornamentation with a pair of coarse ribs prolonging arm axis; six small transverse ridges in each interradius and a coarse transverse rib in upper part of radial ring (Fig. 6 b). Length of preserved stalk 165 mm; proximalmost diameter (Dp) 2.4 mm, decreasing to 1.78 mm (Dm) with relative thickness (H/D) 0.45 at a distance of 41 mm from aboral cup; distal diameter 1.95 mm; heptagonal proximal columnals becoming cylindrical distally; columnal height increasing to 1.3 mm with H/D 0.69 at 55 mm before broken stalk end; H/D 0.56 in distalmost columnal. Stalk symplexies as in the holotype with 7 crenular units of 1–2 crenulae (Fig. 7 d); beginning of syzygial crenularium development at end of preserved stalk (Fig. 7 e–f). Specimen T 629 -A 4 - 2: Maximum arm length 104 mm, with 28 to 30 pinnules on each arm side; maximum pinnule length 42 mm between Br 30 and 34. Beyond Br 4, first free brachial at Br 13 (4 cases) or Br 15 (1 case); maximum number of 5 or 6 successive muscular articulations from Br 19 to Br 35; more distal pattern strongly variable from only successive brachial pairs all along distal arm (1 case) to series of more than 15 successive muscular articulations (1 case). Tegmen more inflated than in preceding specimen but less than in holotype, attached on three proximal brachials only in anal interradius (Fig. 5 b); height at oral cone 8.2 mm; height of aboral cup 8.7 mm; radial height 5.5 mm; diameter at base of basal ring 3.1 mm; diameter at top of radial ring 9.8 mm; relative interray width (Wr/Wb) 2.15 + 0.12. Two fine ridges resembling dotted lines on cup ribs prolonging arm axis; transverse ridge irregular and variable; base of basal ring moderately flanged (Figs. 6 c, d). Length of preserved stalk 80 mm; proximalmost diameter 2.7 mm, decreasing to 1.86 at a distance of 35 mm below aboral cup; distal diameter 1.89 mm with H/D 0.61; hexagonal proximal columnals with heterometry (variable thickness and diameter) less than in other specimens; stalk symplexies with 6 crenular units of 1–2 crenulae. FIGURE 8. Gephyrocrinus messingi n. sp. , theca and crown in paratypes. a and b: paratype T 629 -A 4 - 2; c: paratype T 629 -A 4 - 1; a and c: theca and proximal crown; b: distal arm. PARATYPES FROM SAN JUAN (SIO E 4427): Two specimens significantly smaller than holotype, with stalk and crown. Specimen T 662 -A: Crown quite well preserved but with three arms separated from proximal part (two arms broken at muscular articulation 6–7, one broken at synostosis 7 + 8), and one broken at muscular articulation 13–14. Beyond Br 4 bearing first pinnule, first free brachial at variable locations from Br 11 to Br 15; series more than two successive muscular articulations from Br 23 with a maximum of 10. Conical aboral cup and tegmen partly crushed; aboral cup with coarse pairs of ribs prolonging arm axes and base of basal ring bearing 7 knobs aligned with series of knobs on proximal stalk; series of granules in the area of transverse ridges; moderately inflated tegmen with verrucose ornamentation; anal sac equal or slightly taller than oral cone; triangular orals well developed with concave outer surface and one finger-like projection at base. Length of preserved stalk 39 mm; middle and distal stalk missing; proximalmost diameter 2.2 mm, decreasing to 1.56 mm at distal end; minimum diameter undoubtedly smaller than 1.5 mm. Proximal columnals heptagonal with conspicuous heterometry (diameter and thickness variable) up to 20 mm from aboral cup, becoming cylindrical distally. At distal end of preserved stalk, symplexies with 7 crenular units of 2–3 short crenulae; claustrum present; concave areolar lobes between crenular units (Figs. 7 b, c). FIGURE 9. Gephyrocrinus messingi n. sp. , SEM micrographs of pinnule architecture. a: paratype T 629 -A 4 - 1; b to d: paratype T 629 -A 4 - 2; a: lateral view of proximal genital inflation; b: same pinnule, mid-distal part; c: well developed cover plates; d: distal end rolled up; lp: lateral plates; cv: cover plates. Specimen T 662 -B: Juvenile specimen quite complete, only distalmost stalk missing and two arms broken at muscular articulation 13–14 and 14–15. Beyond Br 4 bearing first pinnule, first free brachial appearing at Br 5 (1 case), Br 7 (1 case), Br 9 (2 cases) and Br 11 (1 case). Series of more than two successive muscular articulations appearing from Br 15 to Br 18; maximum number observed 5 (1 case). Brachial constriction midway between two muscular articulations more conspicuous than in other specimens, especially in proximal arm. Same general ornamentation as in preceding specimen but less conspicuous on aboral cup, and more conspicuous and very spiny on tegmen. Tegmen not inflated; number of tegminal plates per interradius less than 12; relatively large orals with finger-like projection at top; oral cone and anal sac tops at about the same level. Stalk length 122 mm; proximalmost diameter 1.3 mm, decreasing to 0.78 mm at a distance of 11 mm, increasing to 0.80 mm at 25 mm and up to 1.01 mm at distal end; H/D up to 0.6 distally. Mesistele symplexy (Figs. 10 a to e) with 6 crenular units of 1 very short crenula, and marked areolar depression around perilumen especially at maximum columnal height (Fig. 10 e). Distal syzygy with radial crenularium (Fig. 10 f). Remarks and affinities. The five specimens described here belong undoubtedly to the same species and illustrate morphological variations both related and unrelated to ontogeny. They constitute a growth series from the most juvenile specimen (T 662 -B) to the largest (T 629 -A 4 - 2). Tables 2–3 show that all the basic quantitative variables of aboral cup and stalk depend on growth, whereas ratios are independent of size (Hc/Dc, Hr/Wr, Wr/Wb, Dc/ Drb). In this case, detecting ontogenetic trends in morphological changes is difficult due to the small number of specimens. However, arms seem to grow more rapidly than pinnules, radials than basals, and size of aboral : Published as part of Roux, Michel & Lambert, Philip, 2011, Two new species of stalked crinoids from the northeastern Pacific in the genera Gephyrocrinus and Ptilocrinus (Echinodermata, Crinoidea, Hyocrinidae). Effects of ontogeny and variability on hyocrinid taxonomy, pp. 1-54 in Zootaxa 2825 on pages 6-17, DOI: 10.5281/zenodo.277262 : {"references": ["Roux, M. & Pawson, D. L. (1999) Two new Pacific Ocean species of hyocrinid crinoids (Echinodermata), with comments on presumed giant-dwarf gradients related to seamounts and abyssal plains. Pacific Science, 53, 3, 289 - 298.", "Roux, M. (2004) New hyocrinid crinoids (Echinodermata) from submersible investigations in the Pacific Ocean. Pacific Science, 58, 4, 597 - 613.", "John, D. D. (1937) Crinoidea. Resultats du voyage de S. Y. \" Belgica \", Expedition antarctique belge, Rapport scientifique, Zoologie, Anvers: 1 - 11.", "Mironov, A. N. & Sorokina, O. A. (1998 b) Sea lilies of the order Hyocrinida (Echinodermata, Crinoidea). Zoologicheskie Issledovania, 2, 1 - 117 (in Russian).", "Roux, M. & Bohn, J. (2010) Revision of Gephyrocrinus grimaldii Koehler & Bather, 1902 (Echinodermata, stalked Crinoidea, Hyocrinidae). Zoosystema, 32, 3, 425 - 437.", "Ameziane, N. & Roux, M. (1997) Biodiversity and historical biogeography of stalked crinoids (Echinodermata) in the deep sea. Biodiversity and Conservation, 6, 1557 - 1570.", "Roux, M. (1980) Les articulations du pedoncule des Hyocrinidae (Echinodermes, Crinoides pedoncules): interet systematique et consequences. Bulletin du Museum national d'Histoire naturelle, Paris, 4 e serie, 2, section A, 1, 31 - 57.", "Agassiz, A. (1892) Calamocrinus diomedae, a new stalked crinoid. Memoirs of the Museum of Comparative Zoology, Harvard, 17, 2, 1 - 95."]}