Muricea cacao, Hernández & Gómez-Gutiérrez & Galván-Tirado & Sánchez, 2023

Hernandez, Osvaldo, Gomez-Gutierrez, Jaime, Galvan-Tirado, Carolina & Sanchez, Carlos, 2023, Three new species of the sea fan genus Muricea (Cnidaria, Octocorallia, Plexauridae) from the northwest region of Mexico, ZooKeys 1169, pp. 333-352 : 333

publication ID	https://dx.doi.org/10.3897/zookeys.1169.89651
publication LSID	lsid:zoobank.org:pub:B3CBCC79-BEE8-41B9-A8AB-69426EC0FBDA
persistent identifier	https://treatment.plazi.org/id/F91F41A5-DAA5-4D47-9E62-812EFDAFC7D6
taxon LSID	lsid:zoobank.org:act:F91F41A5-DAA5-4D47-9E62-812EFDAFC7D6
treatment provided by	ZooKeys by Pensoft
scientific name	Muricea cacao
status	sp. nov.

Treatment

Muricea cacao sp. nov.

Material examined.

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 View Figure l ) GoogleMaps . 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 GoogleMaps ; 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 GoogleMaps ; 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 View Figure l ) GoogleMaps . The type specimens were collected by Carlos Sánchez.

Holotype colony description.

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 View Figure 4 , Table 1 View Table 1 ). Polyp rows distribute imbricated (Table 1 View 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 View Figure 4 ). 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 View Figure 4 ). 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 View Figure 4 ). 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.

Holotype sclerites.

The sclerites of the outer coenenchyme and calyces are dark brown or reddish-brown (Fig. 4B View Figure 4 , Table 1 View Table 1 ). In the outer coenenchymal leaf spindles with a very strongly thorny appearance 0.4-1.7 mm length are dominant (Fig. 5A View Figure 5 ); sclerites are also tuberculated spindles with acute ends (1.4 mm in length) (Fig. 5B View Figure 5 ). 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 View Figure 4 , 5C View Figure 5 ).

Morphological variation.

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 View Figure 4 ) 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 View Figure 8 ). The polyps in living colonies have white neck and colorless tentacles (Fig. 8D View Figure 8 ; Suppl. material 1: fig. S2F).

Habitat and distribution.

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 View Figure l ). Muricea cacao sp. nov. (Fig. 1C View Figure l ) and Muricea ambarae sp. nov. (Fig. 1B View Figure l ) share similar distribution and habitat.

Remarks.

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 View Figure 4 ) is similar to Muricea ambarae sp. nov. (Fig. 2A, B View Figure 2 ) 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 View Figure 8 , Table 1 View 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 View Figure 3 ), while M. cacao sp. nov. has even more strongly unilateral multi-spinous spindles, and an absence of tuberculated, bent spindles (Fig. 5A-C View Figure 5 , Table 1 View 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 View Table 1 ), we propose to include both species in the Muricea 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 View Figure 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).

Etymology.

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.