Botanica Marina 2019; aop Short communication D. Wilson Freshwater* and Laila Shahnaz Phylogenetic relationships of Pakistan Gelidium (Gelidiales, Rhodophyta) species with recognition of Gelidium pakistanicum stat. nov. https://doi.org/10.1515/bot-2018-0121 Received 28 December, 2018; accepted 15 February, 2019 Abstract: Two species of Gelidium, Gelidium usmanghanii and Gelidium pusillum var. pakistanicum are reported only from Pakistan, but their taxonomic status, phylogenetic relationships, and distributions have not been assessed with molecular data. Analysis of rbcL sequences revealed that G. usmanghanii was a distinct species with a distribu- tion extending at least to the coast of Oman. This analy- sis also resolved G. pusillum var. pakistanicum within a Gelidium millariana species complex that was distantly related to G. pusillum. Further analyses of rbcL and COI- 5P sequences showed that G. pusillum var. pakistanicum was a distinct species in this complex, and based on these molecular, and previous morphological results, this vari- ety is elevated to the rank of species as Gelidium pakistani- cum stat. nov. Keywords: COI-5P barcode; Gelidium pusillum var. pakis- tanicum; Gelidium usmanghanii; rbcL; taxonomy. Pakistan’s ca. 990 km of coastline borders the northern Arabian Sea and encompasses a variety of marine habi- tats (MFF Pakistan 2016). Over 300 species of marine macroalgae are reported along this coastline (Anand 1943, Shameel et al. 1989, 1996, Shameel and Tanaka 1992, Shameel 1999, 2001, Guiry and Guiry 2018), but this number includes only two Gelidiales species, Gelidium pusillum var. pakistanicum Afaq-Husain et Shameel and Gelidium usmanghanii Afaq-Husain et Shameel. Published reports of both species are restricted to the Pakistan coast (Silva et al. 1996, Afaq-Husain and Shameel 1999, Kokabi and Yousefzadi 2015), but specimens of G. usmanghanii from the Arabian Sea coast of Iran are deposited in the University of Michigan herbarium (Macroalgal Herbarium Portal 2018). Early surveys of marine algae from the coast of Paki- stan listed only one Gelidium species, Gelidium pusillum (Stackhouse) Le Jolis (e.g. Anand 1943, Shameel et al. 1989). A second species, Gelidium usmanghanii, was included in the study of Naqvi et al. (1992), but the name was only validly published in 1996 (Afaq-Husain and Shameel 1996). A recent FT-IR spectroscopy study showed that it produces a food-grade agar, and may have economic importance (Shahnaz et al. 2019). Gelidium usmanghanii was distinguished by the delicate texture of the thallus, and erect axes that were spiraling, flattened, but some- what lanceolate in transverse section. Erect axes were also irregularly branched and had undulating margins with congested marginal proliferations (Afaq-Husain and Shameel 1996, Shahnaz and Khalid unpubl. obs.). Origi- nally cited as being in the Pakistan Council of Scientific and Industrial Research (PCSIR) herbarium, the holotype and one isotype specimen of this species are now depos- ited in the University of Karachi herbarium (KUH). The presence of Gelidium pusillum on the Pakistan coast was questioned by Afaq-Husain and Shameel (1997), who later ascribed Pakistan specimens identi- fied as such to a new variety, G. pusillum var. pakistani- cum (Afaq-Husain and Shameel 1999). They reported that the Pakistan taxon differed from Northeast Atlantic G. pusillum in habitat, size, texture and color, as well as the shape and branching pattern of erect axes (Table 1). The objectives of this study were to clarify the taxo- nomic status of Gelidium pusillum var. pakistanicum and determine the phylogenetic relationships of it and Gelid- ium usmanghanii through analyses of rbcL and COI-5P sequence data. DNA extraction, gene amplification and sequencing followed the procedures outlined in Taylor et al. (2017) and Hardesty and Freshwater (2018) using primers described in Freshwater and Rueness (1994), and Saunders and Moore (2013). Maximum likelihood *Corresponding author: D. Wilson Freshwater, Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, NC 28409, USA, e-mail: freshwaterw@uncw.edu Laila Shahnaz: Department of Botany, University of Karachi, Karachi 75270, Pakistan Brought to you by | University of California - Santa Barbara Authenticated Download Date | 3/17/19 7:21 PM