Three new species of the sea fan genus Muricea (Cnidaria, Octocorallia, Plexauridae) from the northwest region of Mexico Author Hernandez, Osvaldo https://orcid.org/0000-0001-6195-149X Departamento de Plancton y Ecologia Marina, Centro Interdisciplinario de Ciencias Marinas, Instituto Politecnico Nacional, Av. IPN, s / n, CP 23096, La Paz, Baja California Sur, Mexico & Departamento de Ciencias Marinas y Costeras, Universidad Autonoma de Baja California Sur, Carretera al sur km 5.5, CP 23080, La Paz, Baja California Sur, Mexico Author Gomez-Gutierrez, Jaime https://orcid.org/0000-0003-2516-897X Departamento de Plancton y Ecologia Marina, Centro Interdisciplinario de Ciencias Marinas, Instituto Politecnico Nacional, Av. IPN, s / n, CP 23096, La Paz, Baja California Sur, Mexico Author Galvan-Tirado, Carolina https://orcid.org/0000-0003-3973-256X Departamento de Ciencias Marinas y Costeras, Universidad Autonoma de Baja California Sur, Carretera al sur km 5.5, CP 23080, La Paz, Baja California Sur, Mexico & Consejo Nacional de Ciencia y Tecnologia, Av. Insurgentes Sur 1582, Col. Credito Constructor, Alcaldia Benito Juarez, C. P. 03940, Ciudad de Mexico, Mexico Author Sanchez, Carlos https://orcid.org/0000-0001-7199-1268 Departamento de Ciencias Marinas y Costeras, Universidad Autonoma de Baja California Sur, Carretera al sur km 5.5, CP 23080, La Paz, Baja California Sur, Mexico csanchez@uabcs.mx text ZooKeys 2023 2023-07-18 1169 333 352 http://dx.doi.org/10.3897/zookeys.1169.89651 journal article http://dx.doi.org/10.3897/zookeys.1169.89651 1313-2970-1169-333 B3CBCC79BEE841B9A8AB69426EC0FBDA 339DE2775B2E5D73ABF700229725DF0E Muricea ambarae sp. nov. Material examined. 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, Bahia de Las Animas ( 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 Sanchez . Holotype colony description. 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 ). Table 1. Internal and external characters of Muricea ambarae sp. nov., Muricea cacao sp. nov. and Muricea molinai sp. nov. with similar Muricea nominal species distributed along the Mexican Pacific and Gulf of California collected from 1998-2020 and compared with Breedy and Guzman (2015 , 2016a ). Colony growth : bu = bushy, fa = falling branches, fl = flabellate. Branching type : di= dichotomous, irr = irregularly, lb = laterally branched, ob = open branched. Polyp distribution rows : im = imbricated, c = close, s = sparsely. Calyx form : el= elongated, sl = shelf-like, t = tubular. Color : am = amber, br = brownish-red, bi = bicolor, cl = colorless, db = deep brown, dy = dull yellowg = gray, lb = light brown, lo = light orange, o = orange, ro = reddish-orange, py = pale yellow, r = red, rb = reddish-brown, y = yellow, w = white. Sclerites : ae = acute end spindles, bs = branched spindles, be = bend spindles, cs = curved spindles, cl= club-like, de = dull ends spindles, lb = lobed, ls = leaf spindles, ps = prickly spindles, r = rods, slr = star-like radiates, str = straight spindles, tbr = tuberculated rods, tbs = tuberculated spindles, uss = unilateral spinous spindles, ws = warty spindles, wr = warty rods.

Species	Colony growth	Branching type	Terminal branches length (cm)	Polyp distribution rows	Pseudoanastomosis	Calyx height elevation (mm)	Calyx form	Colony Color	Outer coenenchymal and calyx dominant spindles	Coenenchymal and calycular spindles maximum size (mm)	Inner coenenchymal spindles	Anthocodial sclerites	Sclerites color
M. californica	bu	irr, lb	2.8	c, im	no	1.9	el	ro	ls	0.5	slr, ws	lb, wr	am, lo, ro, py
M. echinata	bu	irr, lb	6-3	c	no	2.8-3	sl	rb	uss	2.4	ws	r, bs	o, lb
M. fruticosa	bu	irr	1.5-4	c	no	1-1.2	sl	rb, w, bi	uss	2	ws	ws, wr, bs	w, rb, py
M. galapagensis	fa	ob	8	s	no	0.6-1	sl	lo	uss	4.1	ws	r, ps	am, lo
M. plantaginea	fl	irr, lb	1-5	c, im	no	0.7-1.2	sl	db/w	ls	1	ws	lb, wr	rb, am
M. squarrosa	fl	di	4	c	no	2.6	t	lb	cl, cs	1.3	tbs	cl	br, cl, py, y
M. ambarae sp. nov.	fl	lb	9.5	im	no	1	sl	o	ls, tbs	1.2	ws	lb	cl, o, y, py
M. cacao sp. nov.	fl	lb	9	im	yes	1	sl	br-r	ls	1.7	ae/de-ws	tbr-ae	db, rb
M. molinai sp. nov.	fl	lb	8.7	im	no	3	t	g	uss, tbs	2.5	str, cs	tbr, lr	g, am, cl

Figure 2. Muricea ambarae sp. nov. A holotype USNM 1606629 B holotype detail of branches C axial and coenenchymal sclerites. Holotype 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. Morphological variation. 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). Habitat and distribution. 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 Bahia 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 Bahia 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 Bahia Magdalena with Leptogorgia diffusa (Verrill, 1868), Muricea cacao sp. nov., M. molinai sp. nov., M. plantaginea , M. fruticosa , and Psammogorgia teres Verrill, 1868. Remarks. 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. Etymology. 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 ( Ambar ) of Carlos Sanchez .