Bathypathes thermophila Chimienti, 2022
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publication ID |
https://dx.doi.org/10.3897/zookeys.1116.79846 |
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lsid:zoobank.org:pub:5A9FB0AB-B37B-4569-A1F0-16DFB9AE3F7A |
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https://treatment.plazi.org/id/6D09BCE9-D0B6-4DA0-922A-2324A29380B3 |
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taxon LSID |
lsid:zoobank.org:act:6D09BCE9-D0B6-4DA0-922A-2324A29380B3 |
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treatment provided by |
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scientific name |
Bathypathes thermophila Chimienti |
| status |
sp. nov. |
Bathypathes thermophila Chimienti sp. nov.
Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5
Material examined.
Holotype: MNHN-IK-2016-45 (Fig. 2 View Figure 2 ), Red Sea, Duba Channel, 27.643801°N, 35.455505°E, 303 m, 9 Oct 2020, Neptune submersible (collection code NTN0028-6). Paratypes: KAUST-NTN0037-8, Red Sea , off Haql ( Gulf of Aqaba ), 29.264796°N, 34.920449°E, 278 m, 21 Oct 2020, Neptune submersible (collection code NTN0037-8); MUZAC-6665, Red Sea , South of Magna ( Gulf of Aqaba ), 28.31497°N, 34.68936°E, 323 m, 25 Oct 2020, Neptune submersible (collection code NTN0040-2); MUZAC-6666, Red Sea , South Sila Island , 27.562322°N, 35.283313°E, 629 m, 12 Oct 2020, Chimaera ROV (collection code CHR0011-2); KAUST-NTN0056-3, Red Sea, off Shusha Island, 27.8933°N, 34.83665°E, 597 m, 7 Nov 2020, Neptune submersible (collection code NTN0056-3) GoogleMaps .
Diagnosis.
Colony attached though a basal disk, monopodial, generally unbranched or with a few, random branches, and pinnulate (Figs 2a, b View Figure 2 , 3a-e View Figure 3 ). Stem cylindrical (Fig. 2c View Figure 2 ), regularly decreasing in diameter from the base to the top. Lower unpinnulated section of the stem (stalk) much shorter than upper pinnulated section. Pinnules simple, up to 20 cm long and subequal in length over most of the corallum, except for proximal and distal ones that are shorter. Pinnules arranged alternately in two lateral rows along the stem (Fig. 2d View Figure 2 ), although one or few couples of pinnules can be occasionally present on the same side (Fig. 3f View Figure 3 ). Pinnules inclined of 30° in frontal view (Fig. 2d View Figure 2 ) and oriented slightly forward in the polypar side with respect to the stem. Pinnular basal diameter 0.18-0.40 mm (0.11 in young colonies). Spacing of pinnules on the same side 2.8-4.3 mm (Fig. 2d View Figure 2 ), with a pinnular density of 12-18 per 3 cm (up to 20 in young colonies), including pinnules on both sides.
Spines on the pinnules smooth, laterally compressed, triangular, acute, simple or rarely bifurcated, 0.015-0.025 mm tall (occasionally down to 0.008 mm or up to 0.028 mm), with polypar spines almost the same size of abpolypar ones or slightly larger. Four or five rows of spines in lateral view, each row bearing from one to three spines (Fig. 4d-i View Figure 4 ), with a density of 5-8 spines per mm (considering double or triple spines as one). Rows can be less obvious on some pinnules.
Spines on the stem smooth, laterally compressed, triangular in profile, acute, simple and enlarged at the base, 0.020-0.030 mm tall. Spines uniformly distributed around the stem, arranged in 10-14 longitudinal rows, each one bearing one to three parallel spines (Fig. 4a-c View Figure 4 ). Spines often random on the proximal stem and near the basal disk. Basal disk with numerous, elongated spines up to 1.2 mm tall.
Polyps present on one side on both pinnules and stem (Fig. 2e View Figure 2 ), elongated along the transverse axis, 1.5-2.5 mm in transverse diameter (rarely smaller or larger) and 0.5 mm large (Fig. 2f-i View Figure 2 ). Polyps sharply divided into three regions, with pairs of tentacles 0.5 mm long (contracted polyps) and 0.2-0.3 mm apart, and prominent oral cones. Polyps distance ranging from 0.5 to 2.5 mm, generally 1 mm, with a density of 10-15 polyps per 3 cm.
Description of the holotype.
The holotype (MNHN-IK-2016-45) is a complete colony with an intact basal disk and apex. The colony is attached to the subfossil remains of an irregular echinoid encrusted by various small invertebrates. The colony is 74.5 cm long with a stem basal diameter of 1.8 mm. The unpinnulated stalk is 4 cm long. The basal disk is 7 mm in diameter with numerous, erect and acute spines, up to 0.9 mm tall, all over its surface. The pinnules are simple, bilateral and arranged alternately. Although pinnules are quite flexible, some of them are broken off. The longest remaining ones are ~ 20 cm in length with a basal diameter of ~ 0.28-0.40 mm. The number of pinnules on the corallum is 186 on one side and 181 on the other. Some pinnules are missing at the base of the corallum, likely broken and lost during collection with the sampling manipulator. Within each row, the pinnules are spaced 2.8-3.5 mm apart on the apical portion of the corallum, 3.2-3.7 mm on the middle area and 3.4-4.0 mm on the basal one. The resulting pinnular density is 14 per 3 cm (total for both rows) on the proximal portion of the stem to ~ 16-18 per 3 cm in the median and towards the distal end. The central axial canal is 0.31 mm wide on a pinnule 0.42 mm in diameter, and 0.10 mm on a pinnule 0.22 mm in diameter.
The stem is characterised by six or seven rows of spines in lateral view, although in some areas their distribution can be irregular. A single, 4-cm branch is present in the proximal area of the corallum, and a dichotomous ramification is present in the median area (Fig. 3c, d View Figure 3 ).
Pinnular spines are small, from 0.017 to 0.022 mm tall, and 0.20-0.31 mm apart. Spines can be double or triple, particularly in the proximal portion of pinnules. Bifurcated spines are also present, although not common.
The polyps are 1.5-2.0 mm in transverse diameter, rarely smaller than 1.5 mm. Polyps density is 11-15 polyps per 3 cm on the stem and 11-13 polyps per 3 cm on the pinnules.
Description of the paratypes.
The general morphology of the four paratypes analysed is similar to that of the holotype, with a monopodial corallum and pinnules simple, bilateral and arranged alternately. All paratypes have elongated polyps occurring in a single series on one side of the pinnules and of the stem.
Paratype KAUST-NTN0037-8 is a complete colony of 27 cm in length (Fig. 5a, b View Figure 5 ), with a stem basal diameter of 1 mm. The unpinnulated stalk is 2.8 cm long, while the basal disk is 4 mm in diameter with tall spines, up to 1 mm, erect or curved upwards. The pinnules are up to 9 cm long with a basal diameter of 0.25-0.35 mm and a pinnular density of 14-16 per 3 cm (Fig. 5c View Figure 5 ). Distance between adjacent pinnules on one side of the stem is 3.3-4.2 mm, except for one couple of pinnules in the median part of the colony that is not alternately arranged. The stem is characterised by six rows of spines in lateral view, although in some areas their distribution is more irregular. Rows are uniformly distributed around the stem, and host spines 0.020-0.028 mm tall. Spines on the pinnules are 0.018-0.022 mm tall, and 0.13-0.20 mm apart (Fig. 5e View Figure 5 ). Each pinnule bears 4-5 rows of spines in lateral view. Polyps are generally 1.9-2.5 mm in transverse diameter (Fig. 5d View Figure 5 ), rarely up to 3.0 mm, while young ones can be only 1.3 mm. They are mostly 1 mm apart, although distance can range between 0.8 and 2.3 mm. Density of 10 polyps per 3 cm.
Paratype MUZAC-6665 is a complete colony of 45 cm in length (Fig. 5f, g View Figure 5 ), with a stem basal diameter of 1.6 mm. The unpinnulated stalk is 3 cm long, while the basal disk is 6.2 mm in diameter with spines up to 1.2 mm tall, erect or curved upwards. Pinnules up to 16 cm long with a basal diameter of 0.30-0.40 mm and a pinnular density of 12-15 per 3 cm. One couple of pinnules at the median and two at the distal part of the stem interrupt the alternate arrangement, being on the same side. A single, primary branch is present on one side of the colony and a single, secondary one on the other side (Fig. 3e View Figure 3 ). Pinnular spines 0.021-0.028 mm tall, 0.12-0.30 mm apart, and arranged in 4-5 rows in lateral view (Fig. 5i View Figure 5 ). Spines on the stem arranged in 6-7 rows per side and 0.020-0.030 mm tall. Polyps 2.0-2.5 mm in transverse diameter (occasionally up to 3.0 mm or down to 1.3 mm), with a density of 10-12 polyps per 3 cm (Fig. 5h View Figure 5 ).
Paratype MUZAC-6666 is a complete colony of 14 cm in length (Fig. 5j View Figure 5 ), with a stem basal diameter of 0.6 mm. The unpinnulated stalk is 1.6 cm long, while the basal disk is 4 mm in diameter with spines up to 0.8 mm tall (Fig. 5m View Figure 5 ). The pinnules are up to 7 cm long with a basal diameter of 0.11 mm and a pinnular density of 18-20 per 3 cm. The pinnules are characterised by four or five rows of spines in lateral view, with spines 0.012-0.016 mm tall and 0.10-0.22 mm apart (Fig. 5l View Figure 5 ). Polyps are 1.5-2.0 mm in transverse diameter, 1.5-2.0 mm apart, with a density of 9-10 polyps per 3 cm (Fig. 5k View Figure 5 ).
Paratype KAUST-NTN0056-3 is a complete colony 26 cm long, with a stem basal diameter of 0.9 mm. The unpinnulated stalk is 3.0 cm long, while the basal disk is 2.7 mm in diameter with tall spines, erect or curved upwards, up to 0.9 mm tall. Pinnules up to 11 cm long with a basal diameter of 0.18-0.26 mm and a pinnular density of 14-17 per 3 cm. Pinnules are alternate, with adjacent ones spaced 3.2-4.3 mm, except for one, single pair of pinnules present on the same side of the stem, in the median part of the colony. The central axial canal is 0.07 mm in diameter on a pinnule 0.12 mm in diameter. Pinnules with four rows of spines in lateral view, mostly 0.008-0.012 mm tall (some up to 0.018 mm) and 0.10-0.18 mm apart. Stem bearing five rows of spines in lateral view, 0.016-0.020 mm tall. The colony was found dead, without polyps.
Etymology.
The species name is derived from the Greek words thermos (hot) and philia (love, preference for), referring to the occurrence of this species in the rather warm Red Sea waters, especially compared to the water temperatures usually measured in other bodies of water within the same depth range.
Distribution.
A colony matching the macro-morphology of B. thermophila sp. nov. is shown in Qurban et al. (2014: fig. 3F), where it is reported as an "unidentified sea fan". It is reported from two areas off Duba (Fig. 1 View Figure 1 ), at 360-720 m depth, extending the known distribution further south from our sampling area. To date, B. thermophila sp. nov. is only known from the Gulf of Aqaba and northern Red Sea (Fig. 1 View Figure 1 ), from 195 to 720 m depth.
Habitat and ecology.
Bathypathes thermophila sp. nov. seems to grow preferentially on scattered hard substrates (e.g., rocks, fresh, fossil or subfossil shells, coral rubble, and subfossil sea urchin tests) surrounded by mud, although it can occur also on rocky bottoms. The holotype (MNHN-IK-2016-45) had settled on a subfossil test of an irregular echinoid, recovered on a sloping rocky substrate covered in a thin muddy layer. The paratypes occurred on muddy bottom with scattered biogenic small substrates (KAUST-NTN0037-8, MUZAC-6665) and on hardground surrounded by mud (MUZAC-6666, KAUST-NTN0056-3).
Water temperature on the seabed was 22 °C, as also reported off Duba by Qurban et al. (2014: fig. 6), indicating that B. thermophila sp. nov. lives in relatively warm waters. The species is quite common in the bathyal zone of the Red Sea, where a total of 335 colonies were observed within this study (Suppl. material 1, 2). Aggregations of up to two colonies m-2 were found at 280-300 m depth in two different areas (Fig. 1 View Figure 1 , Suppl. material 1), where B. thermophila sp. nov. was the only erect organism (Fig. 6a-d View Figure 6 ). There, it enhances the benthic structural complexity on flat or gently sloping seabed covered by a mud veneer. B. thermophila sp. nov. is often used as habitat by crinoids, spider crabs, and other epibionts (Fig. 6c-e View Figure 6 ).
Comparisons.
Within the genus Bathypathes , B. platycaulus Totton, 1923 and B. pseudoalternata Molodtsova, Opresko and Wagner 2022 show alternate subpinnules. The former is characterised by a peculiar broadening of the stem in the middle region, to which the species name refers ( Totton 1923), while B. thermophila sp. nov. has a cylindrical stem all along the corallum which lacks a flattened region. Bathypathes thermophila sp. nov. also differs from B. platycaulus in the pinnular rows of spines (four or five per side homogenously distributed vs. six or seven on one side and four on the other) and in the size of the spines (0.015-0.025 mm vs. 0.040 mm). Finally, the basal diameter of the stem of B. platycaulus increases in width in the first 7 cm (from 1.5 mm to 1.75 mm) after which it tapers away gradually up to ~ 0.28 mm at the apex ( Totton 1923), being somehow flattered. Conversely, the stem diameter of B. thermophila sp. nov. decreases slightly and constantly from the base to the apex.
Bathypathes thermophila sp. nov. differs from B. pseudoalternata in having a colony which can bear one or a few branches (vs unbranched), higher pinnular density (12-20 vs. 6-12 pinnules per 3 cm), shorter pinnular spines (0.008-0.028 vs 0.030-0.080 mm) with higher density (5-8 vs. 4-5 spines per mm), smaller polyps (1.5-2.5 vs. 3-5 mm in transverse diameter), and higher density of polyps (10-15 vs. 6-7.5 polyps per 3 cm).
Remarks.
Large colonies, approximately higher than 40 cm, can show one or few ramifications (Fig. 3a-e View Figure 3 ). Despite Opresko and Molodtsova (2021) suggesting that monopodial colonies of Bathypathes can have one ramification due to damaging events, skeletal analysis in proximity of the branching in B. thermophila sp. nov. colonies did not reveal signs of past issues, suggesting that occasional branching can be due to the division of a primary polyp. On the contrary, signs of recovery after mechanical damage were observed on the skeletal of B. thermophila sp. nov. without the occurrence of ramifications. These signs were evident mostly as a skeletal swelling (Fig. 3g View Figure 3 ), a chaotic pattern of spines (Fig. 3i View Figure 3 ), or a drastic narrowing of the pinnular section (Fig. 3h View Figure 3 ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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