Pseudothelogorgia hartogi ( van Ofwegen, 1990 )

Pseudothelogorgia hartogi ( van Ofwegen, 1990)

Figs 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10

= Lignella hartogi van Ofwegen, 1990: 164–168 View in CoL , figs 1–3 [original description].

— Pseudothelogorgia hartogi ( van Ofwegen, 1990) View in CoL : van Ofwegen, 1994: 19–21, figs 1–2 [new comb.].

— Pseudothelogorgia hartogi View in CoL : Samimi-Namin et al. 2011: fig. 1 [first live record, Daymaniyat Islands, Gulf of Oman, 18 m depth].

Type locality.

Arabian Sea, 22.53°N, 68.12°E, 57 m ( holotype USNM 83607 ).

Material examined.

Holotype: India • Arabian Sea, India, Gujarat; R/V Anton Bruun; Cruise 4 B; Sta. 221 A , 22.53°N, 68.12°E; 18 November 1963; sediment type sandy green clay (mud); 57 m depth; USNM 83607 About USNM GoogleMaps .

Paratypes: India • 2 colonies and some fragments, Arabian Sea, India, Gujarat; R/V Anton Bruun; Cruise 4 B; Sta. 221 A ; 22.53°N, 68.12°E; 18 November 1963; sediment type sandy green clay (mud); 57 m depth; RMNH.COEL.17782 GoogleMaps • 4 colonies and many fragments; same collection data as preceding; USNM 81904 About USNM (microscope slides only) GoogleMaps .

Other material.

Oman • (one microscope slide 1602), Gulf of Oman, Daymaniyat Islands (D 4) ; 23.8620°N, 58.1042°E; 18 m depth; rocky wall; coll. K. Samimi-Namin; 23 May 2009; RMNH.COEL.39634 GoogleMaps • Gulf of Oman, Daymaniyat Islands; Sta. 59 ; coll. K. Samimi-Namin; 29 January 2022, 15–17 m depth, UF 16054 ( BOMAN 12120 ) .

Description.

The present redescription of Pseudothelogorgia hartogi is based primarily on paratype material ( RMNH.COEL.17782 ). The holotype ( USNM 83607 ) was examined from fragments and permanent slides housed in the RMNH collection, but the colony material was insufficient for SEM. Paratypes, collected at the same station and date as the holotype (Cruise 4 B, Sta. 221 A), are morphologically identical in colony form and sclerite composition ( van Ofwegen 1990, 1994). Accordingly, SEM images and detailed sclerite descriptions are derived from paratypes, with consistency between holotype fragments, slides, and paratypes confirmed in this study. In addition, recently collected material from the Gulf of Oman ( UF 16054 , RMNH.COEL.39634 ) provided supplementary information, including molecular data and the in situ photographs of living colonies.

The paratypes are arborescent colonies about 15 cm tall with sparse lateral branching (Fig. 3 A View Figure 3 ). The branches arise irregularly but are mostly dichotomous, and reach a length of 7 cm. The polyps are cylindrical, arranged in a spiral around the branches (Fig. 3 C View Figure 3 ). They are not retractable into the coenenchyme of the branches, but they are contracted and curved inward toward the axis. The main stem of the colony lacks polyps. There are several parallel furrows on the main axis which extend all the way up and into the smaller branches (Fig. 3 B View Figure 3 ).

Polyps and coenenchyme of branches with slender spindles up to about 0.45 mm long with spines and simple tubercles (Fig. 4 View Figure 4 ).

The polyps have similar spindles up to 0.25 mm long (Fig. 4 A View Figure 4 ), arranged in eight longitudinal tracts when contracted. At the base of the polyps the spindles are irregularly arranged more obliquely and transversely. Tentacles with small spiny rods up to 0.10 mm long (Fig. 4 A View Figure 4 ). The length of the spindles decreases from the main branch and base of the polyp towards the tentacles.

Coenenchyme of branches is thin and translucent, with spindles with simple and complex tubercles up to 0.45 mm long (Fig. 5 A View Figure 5 ). Some of these large spindles are bent and have larger complex tubercles on one side (Fig. 5 A View Figure 5 ). Capstans present only in the coenenchyme of the main stem (Fig. 5 B View Figure 5 ).

Axial cortex composed of fused sclerites (Fig. 5 C View Figure 5 ) surrounding a central tube.

Colour.

Preserved colonies are cream. Tissue on live colonies (additional material) is translucent, and the colonies appear light cream; polyps translucent (Fig. 6 View Figure 6 ). All sclerites colourless.

Variations.

All examined material is consistent in colony morphology and sclerite characters, with very little intraspecific variation observed. Polyps are spirally arranged in all specimens; in preserved colonies they appear contracted and curved inward (Fig. 3 C View Figure 3 ), whereas in living colonies they are extended (Fig. 6 View Figure 6 ). Preserved colonies are cream to beige (Fig. 3 View Figure 3 ), while living colonies are light cream with translucent polyps (Fig. 6 View Figure 6 ). Sclerite types are consistent across specimens, with only minor variation in the relative abundance of capstans and in the development of tubercles (Figs 4 View Figure 4 , 5 View Figure 5 , 7 View Figure 7 – 10 View Figure 10 ). The fused, pavement-like axial cortex is uniform in all material (Fig. 11 A, B View Figure 11 ).

Remarks.

The sclerites of Pseudothelogorgia hartogi differ from species of the genus Thelogorgia in the following characters: the fused sclerites of the axial cortex and the anthocodial rods are smaller, and no pharyngeal spindles are present. The sclerites of the distal part of the polyps of P. hartogi are distinctly smaller and the coenenchyme of the stem contains spindles, rods and capstans. The material ( RMNH.COEL.17194 ) incorrectly identified by van Ofwegen in 1990 as Lignella richardii and used for comparison with Pseudothelogorgia hartogi is now identified as Thelogorgia vossi Bayer, 1991 .

Distribution.

Arabian Sea, Gulf of Oman; Indian Ocean.