Holotype. USNM 1606629: dry, San Esteban Island (Punta Sureste), Sonora, Mexico (28°40.29228'N, 112°33.24035'W), 20 m depth, 20 °C, 20 June 2010 (Fig. 1B). Paratypes. USNM 1606630: dry, San Esteban Island (Punta Noroeste), Sonora, Mexico (28°43.22958'N, 112°36.76110'W), 20 m depth, 21 °C, 17 July 2010; USNM 1606631: dry, Bahía de Las Ánimas (Los Choros), Baja California, Mexico (28°50.36868'N, 113°14.80885'W), 18 m depth, 20 °C, 18 July 2010; USNM 1606632: dry, Punta Abreojos, Pacific coast of Baja California Sur, Mexico (26°41.76060'N, 113°34.59960'W), 21 m depth, 16.5 °C, 24 June 1998 (Fig. 1B). The type specimens were collected by Carlos Sánchez.

Colony with flabellate growth in one plane and laterally branched, 21 cm high and 14.2 cm wide (Fig. 2A, Table 1). The holdfast is an irregular oval, 1.9 cm in length and 1.3 cm wide from which grows the main stem, 5.2 cm in height and 0.5 mm in diameter. There is no coenenchyme on the base of the steam lost during the collect; the base coenenchyme shows a dark gray and brownish bicolored axis. The growth of the branches is lateral and upward. Some terminal branches are short, about 5 mm in length and 3.5 mm in diameter, while the longest ones are 9.5 cm in length and 3.5 mm in diameter (Fig. 2B, Table 1). All the terminal tips are blunt and covered by calyces. Calyces in the colony range up to 1 mm in height and are 1 mm in diameter and are shelf-like in form with an imbricated arrangement. The coenenchyme color is pale yellow, but the coloration of the calyces is reddish-brown, giving the colony an overall pale and dark orange appearance (Fig. 2A, B, Table 1).

Figure 2. 

Muricea ambarae sp. nov. A holotype USNM 1606629 B holotype detail of branches C axial and coenenchymal sclerites.

The sclerites of the outer coenenchyme and calycular are pale yellow or pale orange leaf spindles (0.3–1.2 mm length), tuberculated spindles with blunt ends (0.2–1.1 mm length), and tuberculated spindles with acute ends (0.2–1.1 mm length) (Figs 2C, 3A–D, Table 1). The leaf spindles are more common all around the polyp aperture, and the spindles with acute ends are the dominant type of sclerite in the rest of the coenenchyme (Fig. 3A). The axial sheath comprises thin spindles with acute ends and clubs (0.3–0.9 mm in length) (Fig. 3B, C). These spindles forms have different sizes of tubercles; about 70% of the coenenchyme and calyx sclerites are colorless (Fig. 2C), with the rest of the sclerites pale yellow or pale orange. Anthocodial sclerites are colorless warty rods, 0.2–0.3 mm in length with acute or dull ends (Fig. 3D).

Figure 3. 

Muricea ambarae sp. nov. SEM A, B calycular and coenenchymal sclerites C axial sclerites D anthocodial sclerites.

All 14 colonies of Muricea ambarae sp. nov. examined are morphologically like the holotype in colony growth and sclerite form with colony size range observed in situ between 4 and 32 cm height (Suppl. material 1: fig. S1A–D). Muricea ambarae sp. nov. colonies show differences in color intensity ranging from darker to lighter orange (Suppl. material 1: fig. S1A–D). Only three of these 15 analyzed colonies showed a lax and bushy colony growth form. Qualitative in situ observations showed a dominance of the planar form over the bushy form (Fig. 8A, B). The polyps are colorless or white in live colonies (Fig. 8B; Suppl. material 1: fig. S2B, D).

Muricea ambarae sp. nov. was collected at two locations, the northern and central regions of the Gulf of California (where the species is more frequently collected), and Bahía Magdalena and Punta Abreojos located along the Pacific coast of Baja California Sur, Mexico (Fig. 1B). Muricea ambarae sp. nov. was mostly observed and collected in the Gulf of California on rocky reefs at < 30 m depth and it is currently unknown if this species is present in deeper waters. Muricea ambarae sp. nov. shares habitat with Muricea plantaginea, Muricea fruticosa, Muricea austera, Muricea cacao sp. nov., Leptogorgia alba (Duchassaing & Michelotti, 1864), and Ellisella limbaughi Bayer & Deichmann, 1960. Colonies of M. ambarae sp. nov. distributed in the region of Bahía Magdalena grow on rocky reefs, pebbled seafloors between 5–20 m depth, and in forest-like reefs formed by the brown seaweed Eisenia arborea J.E. Areschoug, 1876 (1–2 m in height) that typically cover large seafloor areas inside the bay. Muricea ambarae sp. nov. shares habitat in Bahía Magdalena with Leptogorgia diffusa (Verrill, 1868), Muricea cacao sp. nov., M. molinai sp. nov., M. plantaginea, M. fruticosa, and Psammogorgia teres Verrill, 1868.

Muricea ambarae sp. nov. (Fig. 2A, B) is similar to Muricea cacao sp. nov. in colony growth form patterns and calyx form (Fig. 4A, C), but dissimilar in dichotomous branching, lack of pseudoanastomosis, colony coloration, and sclerite appearance (Table 1). Muricea ambarae sp. nov. is also close to Muricea fruticosa in the shelf-like form of the calyces, but morphologically differs in colony growth and sclerite composition (Table 1). Muricea fruticosa has a bushy growth pattern, irregular branching and its coenenchyme has unilateral spinous spindles. In contrast, M. ambarae sp. nov. has a planar colony growth, lateral branching, a single chromotype, and leaf spindles (Table 1), and Muricea ambarae sp. nov. has leaf spindles, which are absent in M. fruticosa. Thus, we propose to include Muricea ambarae sp. nov. in the M. fruticosa species-group erected by Breedy and Guzman (2016a). Muricea ambarae sp. nov. is also close to Muricea galapagensis Deichmann, 1941, sharing with that species low shelf-like calyces that spread outward, orange colony coloration, and planar colony growth (Table 1). However, M. galapagensis, like that of M. fruticosa, has falling branches, unilateral spinous spindles, but lacks leaf spindles (Table 1). Muricea californica (Suppl. material 1: fig. S3F–I) is morphologically and biogeographically similar to M. ambarae sp. nov. (Suppl. material 1: figs S1A–D, S3A–E). However, M. californica has high variability in colony growth and coloration and its main population densities occurs in California while M. ambarae sp. nov. is mostly distributed in the northern region Gulf of California and does not show evident morphological variability (Suppl. material 1: fig. S1A–D). We conclude M. californica and M. ambarae sp. nov. are distinct species because they show clear differences in calix form and size, branch diameter and sclerites forms. Muricea ambarae sp. nov. have shelf-like slightly raised calyces, terminal branches of up to 3.5 mm diameter, and an absence of torch spindles in the coenenchyme (Suppl. material 1: fig. S3A–E), while M. californica has prominent and elongated calyces (almost cylindrical), wider branches of up to 0.5 mm thick, and the presence of torch spindles (Suppl. material 1: fig. S3F–I) (Horvath 2019).

Figure 4. 

Muricea cacao sp. nov. A holotype USNM 1606633 B anthocodial and coenenchymal sclerites C holotype detail of branches.

The word “ambarae” means “amber”, a hard, transparent, fossilized resin produced by some trees. Amber has colorations from pale yellow/orange to a dark orange, like the coloration observed in living colonies of Muricea ambarae sp. nov. Mexican amber, also known as Chiapas Amber, dates from 15 to 23 million years old. Since the time of the Mayan culture, its people have believed amber to have healing and protective qualities. The species name is also inspired from the name of the daughter (Ámbar) of Carlos Sánchez.

Holotype. USNM 1606633: dry, San Marcos Island (El Faro-Lobera), Baja California Sur, Mexico (27°15.95706'N, 112°5.51208'W), 15 m depth, 23 °C, 14 July 2010 (Fig. 1C). Paratypes. USNM 1606634: dry, San Marcos Island (El Faro-Lobera), Baja California Sur, Mexico (27°15.95706'N, 112°5.51208'W), 15 m depth, 23 °C, 14 July 2010; USNM 1606635: dry, Salsipuedes Island (Caleta Falsa Norte), Baja California, Mexico (28°43.78506'N, 112°57.88512'W), 16 m depth, 23 °C, 7 November 1999; USNM 1606636: dry, Bahía de los Ángeles (Punta Pescador), Baja California, Mexico, (28°56.12382'N, 113°22.91976'W), 15 m depth, 20 °C, 19 July 2010 (Fig. 1C). The type specimens were collected by Carlos Sánchez.

The holotype is a brownish-red colony, growing flabellate upwards in one plane and laterally branched, 15.8 cm tall and 8.7 cm wide (Fig. 4A, C, Table 1). Polyp rows distribute imbricated (Table 1). The holdfast is 2 cm length and 1 cm wide with a cream-white color in the area without coenenchyme (lost during collect) (Fig. 4A). Two main branches arise from the base; one is 1.4 cm in length and 4 mm in width, and the other one is 1.3 cm in length and 6 mm wide. They are subdivided into three secondary branches, two of them partially fused (pseudoanastomosis) (Fig. 4A). Several terminal twigs are short (1 cm in length), with several reaching 9 cm in height. In both branches, the average diameter is 3 mm, with blunt ends (Fig. 4C). Calyces are shelf-like, 1 mm in height with a diameter of 1 mm, situated all around the branches in an imbricated arrangement. Calyces are acute in the upper part of the colony or on terminal twigs and blunt at the base.

The sclerites of the outer coenenchyme and calyces are dark brown or reddish-brown (Fig. 4B, Table 1). In the outer coenenchymal leaf spindles with a very strongly thorny appearance 0.4–1.7 mm length are dominant (Fig. 5A); sclerites are also tuberculated spindles with acute ends (1.4 mm in length) (Fig. 5B). The inner coenenchymal sclerites (0.18–0.35 mm length), are thin spindles with blunt or acute ends, most of them colorless (80%), while the rest are pale amber (Figs 4B, 5C).

Figure 5. 

Muricea cacao sp. nov. SEM A, B calycular and coenenchymal sclerites C axial sclerites.

All the Muricea cacao sp. nov. specimens collected and observed in situ are morphologically consistent with the macro- and micro-morphology of both the holotype (Fig. 4A–C) and paratypes with colony size range observed in situ between 2 and 55 cm height (Suppl. material 1: fig. S2E–F). The main differences among Muricea cacao sp. nov. colonies are the growing angle of the branches, the morphology likely influenced by the local water current pattern and available sea floor space on which they grow (Fig. 8C, D). The polyps in living colonies have white neck and colorless tentacles (Fig. 8D; Suppl. material 1: fig. S2F).

Muricea cacao sp. nov. is present in the northern part of the Gulf of California from the Santa Rosalía region to the Midriff Archipelago Region (MAR) and along the Pacific coast of Baja California Sur, between Todos Santos and Bahía Magdalena (Fig. 1A, C). Muricea cacao sp. nov. (Fig. 1C) and Muricea ambarae sp. nov. (Fig. 1B) share similar distribution and habitat.

Paratypes of Muricea cacao sp. nov. have low morphological variability and the main difference is the width of the branches (Suppl. material 1: fig. S4A–C). Muricea cacao sp. nov. (Fig. 4A, B) is similar to Muricea ambarae sp. nov. (Fig. 2A, B) in the colony’s growth form; but differs externally because M. ambarae sp. nov. always has bicolored colonies present; reddish calyces with an orange coenenchyme and does not have pseudoanastomosis as does Muricea cacao sp. nov. In contrast, M. cacao sp. nov. has homogenous brown-reddish coloration in calyces and coenenchyme and has pseudoanastomosis (Fig. 8C, D, Table 1). The main morphological differences between both new Muricea species are in the sclerite forms present; M. ambarae sp. nov. has leaf spindles and the presence of tuberculated, bent spindles (Fig. 3A–D), while M. cacao sp. nov. has even more strongly unilateral multi-spinous spindles, and an absence of tuberculated, bent spindles (Fig. 5A–C, Table 1). However, due to the similarities in colony growth pattern and calyx form between M. cacao sp. nov. and M. ambarae sp. nov. (Table 1), we propose to include both species in the fruticosa species-group proposed by Breedy and Guzman (2016a). Even if Muricea cacao sp. nov. (Suppl. material 1: fig. S2E–F) is comparable with Muricea plantaginea (Suppl. material 1: fig. S2G–J), the later has prominent and elongated calyces, with elongated lower borders curved inwards (Fig. 9). Muricea plantaginea has large colonies of up to 100 cm height, simple leaf spindles and in Mexican living colonies the polyps are always orange or yellow-orange (Suppl. material 1: fig. S2G–I).

The latinized species name “cacao” comes from the ancient pre-hispanic Nahuatl “cacao”, which is the seed used in the making of chocolate, but in Latin is “cacao”, the species name of the cocoa tree is Theobroma cacao L. This “chocolate” color is a practical diagnostic characteristic of both preserved colonies and live colonies with retracted polyps, distinguish this species in situ from other Muricea species.

Holotype. USNM 1606637: dry, Todos Santos, Punta Lobos (Bajo Fondo del Medio), Pacific coast of Baja California Sur, Mexico (23°21.34806'N, 110°15.40374'W), 35 m depth, 19 °C, 27 August 2016 (Fig. 1D). Paratypes. USNM 1606638: dry, Todos Santos, Punta Lobos (Bajo Fondo del Medio), Pacific coast of Baja California Sur, Mexico (23°21.34806'N, 110°15.40374'W), 35 m depth, 19 °C, 27 August 2016; USNM 1606639: dry, Bahía Santa María, Cabo San Lázaro (Roca del Cabito), Pacific coast of Baja California Sur, Mexico (24°44.85966'N, 112°15.56952'W), 29 m depth, 22.4 °C, 13 November 2013 (Fig. 1D). The type specimens were collected by Carlos Sánchez.

Muricea molinai sp. nov. colony coloration is gray with dark gray calyces and a creamy light gray coenenchyme (Fig. 6A, B). The colony is flabellate growing in one plane and laterally branched, reaching 15 cm in height and 14.7 cm in width (Table 1). The holdfast is 22 mm long and 13 mm wide. Two main stems arise from the holdfast one with 2.4 cm and the second one with 4.5 cm in height, subdividing laterally in stems of 7 mm in diameter (Fig. 6A). The growth branching pattern is upward, except six secondary branches, on both sides of the colony, which display more of a downward-growing trend. Terminal branches are up to 8.7 cm tall with blunt ends of 5 mm diameter. Calyces are tubular, 3 mm in height with a 1.5 mm diameter, with an imbricated arrangement throughout the colony (Fig. 6A, B).

Figure 6. 

Muricea molinai sp. nov. A holotype USNM 1606637 B holotype detail of branches and calyces C anthocodial and coenenchymal sclerites.

The sclerites of the outer coenenchyme and calyx are unilateral (weakly) spinous spindles and tuberculated spindles (1.2–2.5 mm in length) (Figs 6C, 7A–C). The spindles are curved or straight; most of them have acute ends or are bifurcated; tuberculated spindles with blunt ends are rare. The inner coenenchymal sclerites are mostly straight or curved spindles with acute ends (0.2–1.2 mm length), but there are rare blunt spindles. Anthocodial sclerites are small tuberculated spindles (1.1–1.8 mm length) with acute ends and rods with marginal lobes and acute ends (Fig. 7D). The color of the outer coenenchymal sclerites is gray, or gray with pale amber areas in the largest ones. The inner coenenchymal and anthocodial sclerites are colorless (Fig. 6C).

Figure 7. 

Muricea molinai sp. nov. SEM A, B calycular and coenenchymal sclerites C axial sclerites D anthocodial sclerites.

All twelve Muricea molinai sp. nov. colony specimens collected, including the paratypes ranging between 7 and 21 cm height (Fig. 8E–G; Suppl. material 1: fig. S5A, B), were morphologically similar to the holotype. No detectable color variability or different colony growth pattern was observed among the examined colonies of M. molinai sp. nov. (Table 1). The length of the tubular calyces is the main morphological variability among M. molinai sp. nov. specimens, where several colonies have longer calyces (> 4 mm in length throughout the colony) than other colonies with shorter calyces (< 2 mm in length). The polyps of live colonies have white neck with translucent brown tentacles (Fig. 8F; Suppl. material 1: fig. S6C).

Figure 8. 

Sea fan colonies photographed in situ A, B Muricea ambarae sp. nov. C, D Muricea cacao sp. nov. E–G Muricea molinai sp. nov. Photographs by Carlos Sánchez.

Muricea molinai sp. nov. is absent in the Gulf of California but overlaps its distribution and habitat with Muricea ambarae sp. nov. and Muricea cacao sp. nov. along the southwest coast of the Baja California Peninsula (Fig. 1B–D). Muricea molinai sp. nov. was collected between Bahía Magdalena and Cabo San Lucas; but it was absent at the Punta Abreojos site (Fig. 1D).

Live colonies of M. molinai sp. nov. (Fig. 8E-G) and Muricea squarrosa (Breedy and Guzman 2015) (Suppl. material 1: fig. S6A–M) are similar, but the shape of the calyces and the differences in the diameter of the branches are the most evident diagnostic feature to distinguish them. Muricea molinai sp. nov. has a distinctive colony coloration, being light gray in the coenenchyme, and dark gray almost black in the calyces which extend sparsely from the base to the tip of the branches (Fig. 8E–G; Suppl. material 1: figs S5A, B, S6C–F). Preserved colonies of Muricea squarrosa are all reddish-brown and without calyces on the base and main stem. The long unilateral spinous spindles (2.5 mm) of M. molinai sp. nov. are one of the longest known spinous spindles among the species of the genus Muricea and without clubs in the coenenchyme and calyx while the spindles of M. squarrosa are smaller, only up to 1.3 mm in length (Verrill 1868 reported spindles of 1.8 mm), and has club-like spindles in the calyx (absent in M. molinai sp. nov.). The main differences to separate Muricea acervata, M. hispida, M. tubigera and M. molinai sp. nov. (species belonging to the M. squarrosa species-group) are the size and arrangement of the calyces and the size of the sclerites. Muricea tubigera has the largest calyces (5 mm length) while M. molinai sp. nov. have calyces of 3 mm length. It is proposed that Muricea molinai sp. nov. be included in the Muricea squarrosa species-group previously erected by Breedy and Guzman (2015).

Muricea molinai sp. nov. is named in memory of Dr. José Mario Molina Pasquel y Henríquez (1943–2020), the first Mexican in 1995 to win the Nobel Prize in Chemistry. Molina played a vital role in the discovery of the Antarctic ozone hole demonstrating that chlorofluorocarbon gases were the cause of the deterioration of the ozone layer.