Chnoospora minima (Hering) Papenfuss

3.1 Chnoospora minima (Hering) Papenfuss ( Figures 4–15 View Figures 4−9 View Figures 10−15 )

Type locality: Port Natal (Durban), South Africa ( Papenfuss 1956).

Observations: Thalli forming bushy tufts, golden brown in color ( Figures 4 – 9 View Figures 4−9 ), attached to the substratum by a holdfast, associated or not with the prostrate, crustose phase of its biological cycle ( Figure 10 View Figures 10−15 ). Erect axes, monopodial, terete to compressed ( Figures 11 and 12 View Figures 10−15 ), 3.5 – 8 (−12) cm in length and variable diameter from the base (400 – 500 × 1,200 – 1,300 µm) at the apical portions (850 – 900 × 1,100 −1,300 µm) and median portions (200 – 250 × 1,300 −1,400 µm); branching dichotomously or trichotomous ( Figures 4−9 View Figures 4−9 ), 2 – 5 times on each axis ( Figures 4−9 View Figures 4−9 ), with acute or blunt apices; branch angle predominantly greater than 50°, curved ( Figures 4−9 View Figures 4−9 ). Segments between branches of variable diameter along the axes, broader at the base of each dichotomy ( Figure 4 View Figures 4−9 ), with variable length, being shorter from the stipe ( 0.5 – 0.8 cm) towards the intermediate portions, where the segments elongate notably ( 2 – 3.5 cm), reducing their size again towards the apical portions ( 0.5 – 1 cm) ( Figures 4 – 9 View Figures 4−9 ). Cryptostomata on axes and branches, numerous, superficial, from which elongated microscopic hairs arise ( Figure 13 View Figures 10−15 ). In cross section, cortex made up of three layers of pigmented, elongated, rectangular cortical cells, relatively constant in diameter between the apical (2.5 × 5 µm) and middle portions (2.5 – 3.5 × 5 µm) and larger in the basal portion (3.5 – 5 × 7.5−8.75 µm) of the axes ( Figure 14 View Figures 10−15 ); medulla made up of 12 – 15 layers of hemispherical, elongated, not very dense cells, with variable diameter in different sections of each axis: apical portion (7.5) 30 – 35 × (5) 12.5−20 µm, middle portion (15) 50−70 µm, and basal portion (15) 25 – 40 × (25) 60−75 µm, reducing progressively in size towards the cortex ( Figures 11 and 12 View Figures 10−15 ), giving the thallus the appearance of being elongated and little branched. Large diameter hollows are observed between the medullary cells in median and basal portions ( Figure 11 View Figures 10−15 ). Sporangia plurilocular elongate, growing uniseriate or biseriate on cortical sori, covered with a loosened cuticle ( Figure 15 View Figures 10−15 ), 60 – 70 µm in length; mature plurangia formed 12−14 locules, quadrangular cells, 3.5 × 5 µm in diameter.

Distribution: Tropical and subtropical coasts of the world. Atlantic Ocean: Ascencion Island ( John et al. 2004), Bahamas ( GBIF 2024), Benin ( John et al. 2004), Brazil ( Taylor 1960), Cape Verde ( John et al. 2004), Colombia ( Schnetter 1976), Cuba ( Suárez et al. 2023), Equatorial Guinea ( John et al. 2004), Ghana ( John et al. 2004), Ivory Coast ( John et al. 2004), Lesser Antilles ( Taylor 1960), Liberia ( John et al. 2004), Martinique ( Delnatte and Wynne 2016), Mexico ( GarcÍa-GarcÍa et al. 2021), Netherlands Antilles ( Taylor 1960), Nigeria ( John et al. 2004), Panama ( Taylor 1960), Puerto Rico ( Ballantine et al. 2021), São Tomé and PrÍncipe ( John et al. 2004), Sierra Leone ( John et al. 2004), Togo ( John et al. 2004), Trinidad and Tobago ( Duncan and Lee Lum 2006) and Venezuela ( Taylor 1960). Indian Ocean: Christmas Island ( Silva et al. 1996), India ( Silva et al. 1996, Yadav et al. 2023), Indonesia ( Silva et al. 1996), Mauritius ( Silva et al. 1996), Mozambique ( Silva et al. 1996), Malaysia ( GBIF 2024), Myanmar (Soe-Htun et al. 2021), Red Sea ( Einav et al. 2021), Réunion ( Silva et al. 1996), Seychelles ( Silva et al. 1996), South Africa ( Silva et al. 1996) and Sri Lanka ( Silva et al. 1996). Pacific Ocean: American Samoa ( Littler and Littler 2003), Australia ( Kraft 2009), Central Polynesia ( Tsuda and Walsh 2013), China ( Liu 2008), Colombia ( GBIF 2024), Easter Island ( Santiañez et al. 2018b), El Salvador ( GBIF 2024), Federated States of Micronesia ( Lobban and Tsuda 2003), Fiji ( South and Skelton 2003), French Polynesia (N ’ Yeurt and Payri 2006), Guam ( Lobban and Tsuda 2003), Hawaiian Islands ( Huisman et al. 2007, Sherwood and Guiry 2023), Japan ( Yoshida et al. 2015), Mariana Islands ( Tsuda 2003), Mexico ( Pedroche et al. 2008, Pedroche and SentÍes 2020), New Zealand ( Nelson et al. 2021), Papua New Guinea ( GBIF 2024), Philippines ( Ang et al. 2014), Revillagigedo Islands ( Serviere-Zaragoza et al. 2007), Samoan Archipelago ( Skelton and South 2007), Solomon Islands ( Womersley and Bailey 1970), Taiwan ( Lewis and Norris 1987), Thailand ( Coppejans et al. 2011), Tuamotu Islands ( Taylor 1973) and Viet Nam ( Nguyen et al. 2013) ( Figure 16 View Figure 16 ).

Habitat: Plants growing in the intertidal zone, on rock walls or rocky platforms, exposed directly to the waves ( Littler and Littler 2003; this study).

3.2 Chnoospora ramosissima Núñez-Resendiz, Dreckmann et Sentíes sp. nov.

( Figures 17−24 View Figures 17−24 )

Description: Thalli forming bushy tufts, yellow to dark, wiry, fixed by a holdfast; erect axes compressed, 6 – 8 (−10) cm length and 1,000 −1,100 µm in diameter, branching profusely, 6 – 8 (to 12) times, dichotomously, with length progressively reducing from the base ( 2.6 – 3 cm) to the tips ( 0.3−0.5 cm) where the branching is most profuse, acute angle; surfaces with numerous cryptostomata associated with short-microscopic hairs; cortex of 2 – 4 layers of golden and rectangular cells, diameter variable in apical portions (3.5 – 45 × 7.5 – 10 µm), middle portions (5 × 7.5 µm), and basal portions (5 × 7.5 – 8.5 µm); medulla of 15 – 18 layers of rounded, large, or irregular cells, compact, diameter slightly variable: 35−50 (−80) µm in apical portions, (25) 40 – 50 µm × (20) 50 – 65 µm in middle portions, and (15) 25 – 40 × 30−50 (−65) µm in basal portions; hollows scattered among the medullary cells, not clearly visible in the basal portions; uniseriate or biseriate sporangia plurilocular without a cuticle; mature plurangia 50 – 80 µm long, subdivided into 10 – 16 squarish locules, 5 µm in diameter.

Type locality: Zihuatanejo, Guerrero, Mexico (17° 66.46 ′ N, 101° 62.41 ′ W; Figure 1 View Figure 1 ).

Holotype: UAMIZ-1515 ( Figure 12 View Figures 10−15 ), Zihuatanejo , Guerrero, Mexico, A. SentÍes; deposited in UAMIZ.

Isotype: UAMIZ-1516, Zihuatanejo , Guerrero, Mexico, A . SentÍes ; deposited in UAMIZ .

Etymology: The specific epithet ( ramosissima = with many branches) refers to the presence of numerous branches in the thallus.

Observations: Thalli were forming bushy tufts, yellow brown in color when fresh to dark when dried ( Figures 17 and 18 View Figures 17−24 ), cartilaginous, wiry, non-lubricated, fixed to the substratum by a holdfast, from which an erect monopodial axis arose ( Figures 17 and 18 View Figures 17−24 ). Erect axes were compressed ( Figure 19 View Figures 17−24 ), 6 – 8 (−10) cm length with constant diameter in the apical (300 – 350 × 1,000 −1,100 µm) and middle (400 × 1,000 −1,100 µm) portions of the axes and notably different and wider in the basal portion (1,100 × 1,800 µm), branching profusely, 6 – 8 (to 12) times, dichotomously, with acute tips; branching angle was predominantly acute and straight, between 45° and less than 90°, slightly curved in older portions ( Figure 18 View Figures 17−24 ). Branching segment diameter was relatively constant along the axes, slightly broader at each dichotomy ( Figure 18 View Figures 17−24 ); the length was progressively reduced from the base to the tips to 2.6 – 3 cm in the basal segment, 0.8 – 1 cm in the intermediate segments and 0.3 – 0.5 cm in the apical portions, giving the thallus the appearance of being profusely branched. Surfaces were smooth, with numerous cryptostomata in axes and branches, associated with short-microscopic hairs ( Figure 20 View Figures 17−24 ).

In cross section, the cortex was made up of three layers of golden cells, rectangular, with different diameters between the apical portion (3.5 – 5 × 7.55 – 10 µm), the middle portion (5 × 7.5 µm), and the basal portion (5 × 7.5−8.5 µm; Figure 21 View Figures 17−24 ); medulla was made up of 15 – 18 layers of rounded, large, or irregular cells, with thick walls, compact, also with different diameters in the apical portion [10 – 35 × 35 – 50 (−80) µm], the middle portion [(25) 40 – 50 × (20) 50−65 µm], and the basal portion [(15) 25 – 40 × 30−50 (−65) µm], with constant size from center to the cortex ( Figure 14 View Figures 10−15 ); as has been described for all the species in Scytosiphonaceae , whose species can be hollow or partially hollow, some hollows appear scattered among the medullary cells, some hollows appear scattered among the medullary cells, without an apparent pattern, not clearly seen in basal sections ( Figure 19 View Figures 17−24 ).

Sporangia plurilocular growing in uniseriate or biseriate cortical sori without a loosened cuticle ( Figures 22−24 View Figures 17−24 ); mature plurangia were elongated, 50 – 80 µm long, subdivided into 10 – 16 squarish locules, 5 µm in diameter.

Habitat: Plants growing on rock walls or rocky platforms, exposed directly to the waves, in the intertidal zone, between 0.5 and 1 m deep, exposed to direct light during low tide. Present throughout the year although they are more abundant in the months of April to September; growing in close association with species of Ectocarpus Lyngbye and Chaetomorpha Kützing.

Distribution: In the Mexican coasts from Zihuatanejo, Guerrero and Faro de Bucerias, Michoacan.