Current status of Schismatogobius marmoratus (Peters, 1868) from West Sulawesi, Indonesia

. Schismatogobius marmoratus (Peters, 1868) was first described from Samar Island, Philippines. Known distributions from Taiwan, Japan, and Indonesia. We collected several specimens from June 2021 to August 2022 during field trips to the Pamboang River, Mosso River, and Leppangan River Majene Regency, West Sulawesi. This study aimed to report the distribution of S. marmoratus from West Sulawesi. Specimens were collected using an electro shocker 120 Volt and 10 amperes, hand nets mesh size 2 mm, and trap nets mesh size 1 mm. Morphometric measurements were taken from point to point using digital calipers with a precision of 0.01 mm. These records extend its occurrence and confirm its widespread distribution in Sulawesi. The discovery of several specimens in Sulawesi increased the urgency of research to determine the distribution and the conservation status of this species, currently listed as least concern (LC) in the International Union for Conservation of Nature (IUCN) red list.


Introduction
Schismatogobius de Beaufort, 1912, a distinctively scaleless genus of small gobies, is found in the tropical Indo-West Pacific.[1].Mostly discovered on gravel, pebbles, and sand substrates, fast-flowing freshwater streams [1].They are amphidromous.However, there is no information on their life histories.[3][4][5].Schismatogobius species exhibit sexual dimorphism in terms of jaw length.Although the lengths of the fins are the same for both sexes, males have noticeably broader jaws than females.[1,6].18 species in all have recently been recognized as belonging to this genus.They are found throughout the Indo-Pacific, from Samoa to southern India.[1,[7][8][9][10].
Schismatogobius marmoratus (Peters, 1868) was described from Samar Island, Philippines.Distributed from Japan, Taiwan, Philippines to Indonesia [1].In Indonesia, currently known from East Java, West Java, and Central Sulawesi [11][12].The paper aims to report on the distribution of S. marmoratus from West Sulawesi and discuss the urgency of research for management and conservation.

Materials and Methods
This study was conducted from June 2021 to August 2022.Sampling was carried out six times during the study: four times in 2021 (June, August, September, and October) and two times in 2022 (April and August).Sampling was conducted along the Pamboang River (-3°29'34"S 118°54'30"E), Mosso River (3°24'38"S 118°51'57"E), and Leppangan River (-3°22'56"S 118°51'52"E) in Majene Regency, West Sulawesi, Indonesia (Fig. 1).using a hand net mesh size of 2 mm, trap net mesh size of 1 mm, and electro shocker 120 Volt and 10 amperes.The specimens were stored in 70% ethanol after being treated with 10% formalin.Specimens were photographed and identified following P. Keith et al. [1], K. Maeda et al. [5].The percentage of standard length (SL) was used to express measurements that were made with a dial caliper to the closest tenth of a millimeter.Each fish had its left side measured and counted.Measurements and counts follow P. Keith et al. [1].

Results and Discussions
Fifteen specimens totaling S. marmoratus were obtained from the Pamboang River, Mosso River, and Leppangan River in Majene Regency, West Sulawesi.This species has a body that is nearly round in cross-section, naked, and slender.Rather pointed snout and head rounded.Eyes that are dorsolaterally situated and near together.Mouth terminal, oblique, and usually with the lower jaw typically jutting outward from the upper jaw.Fin size and shape are the same in males and females.(Fig. 2).The first dorsal fin typically has six spines, and the second dorsal fin typically has a single spine and nine soft rays.The base of the second dorsal fin's spine was attached to the membrane of the first dorsal fin's posterior to the spine.
Typically, 16 pectoral rays, with rows of dark dots banding the pectoral fins.Males have a ventral surface of the head that is whitish with a border, mentum, and isthmus that are all black, and frenum that is somewhat pigmented.Females have a whitish ventral surface of the head with a blackish border, occasionally with a white mentum; the frenum and pelvic disk are typically whitish.Typically, a single spine and nine soft rays are present on an anal fin.Between the first and second soft ray bases of the second dorsal fin is where the anal fin originates.The second dorsal fin is longer than the anal fin.The caudal fin is rounded or shortened.Males and females exhibit sexual dimorphism, with males having longer jaws.The urogenital papilla is slightly triangular in males and broadly rounded in females.Morphomeristic data is given in Table 1.Freshwater gobies have a benthic life as an adult.Research location in West Sulawesi waters has the characteristics habitats of sand with pebbles and gravel substrates, fastflowing, which are one of the habitat preferences for S. marmoratus (Fig. 3).This species is tough to observe in the field because of its cryptic coloration, which blends in with their background.Having a body color similar to the color of the rocks on the substrate is one form of camouflage in Schismatogobius fish, which is quite difficult to distinguish from the substrate.Sometimes, burrow into the pebbles immediately with only the head visible.Thus far, this species has only been found in shallow runs with a substratum of small pebbles.Schismatogbius is known as a type of amphidromous fish whose life cycle is in two different waters and migrates to rivers during the post-larval stage.However, no reports have been related to the post-larvae of Schismatogobius species caught in Indonesian waters.The post-larva fishing activities of amphidromous goby fish are still being carried out because it is one of the consumption fish that is quite popular for people living in coastal areas.In some areas, such as in West Sulawesi, Central Sulawesi, Gorontalo, and West Java, it has become a routine activity carried out by the community to catch amphidromus goby during the migration season during the new moon [13][14][15][16][17][18][19][20].
The genus Schismatogobius is a type of goby that belongs to cryptic species, so it has a variation of shape and color pattern on the body.Identification carried out through morphological and molecular approaches solved the problem of cryptic species so that they can be distinguished from one another [1,[21][22].There is still a lack of research on schismatogobius fish, also a concern.Over the past five years, at least six new species have been described in Indonesia, two of which are endemic (S. risdawatiae from Sumatra and S. limmoni from Sulawesi) [1,[9][10].
Thus far, the species of Schismatogobius reported from Sulawesi Island consist of seven species, namely S. insignus, S. bruynisi, S. arscuttoli, S. saurii, S. Bussoni, S. Sapoliensis, and S. limmoni [1,[9][10].For West Sulawesi, only S. saurii has been reported [16].The species mentioned above until now there has been no evaluation regarding their conservation status.For S. marmoratus status in the International Union for Conservation of Nature (IUCN) red list currently listed as least concern (LC).Freshwater fish inventory also adds information on fish diversity and distribution [23][24].Further research is needed on ecology, reproductive biology, behavior, food and feeding habits, genetics, population status, and other aspects that can complete information for Schismatogobius, especially for endemic species.

Conclusion
This study reports fifteen S. marmoratus specimens collected from three rivers of West Sulawesi as distributional notes.S. marmoratus was found to share the same habitat as S. saurii, this is a note that there is the potential for the existence of other species of Schismatogobius in West Sulawesi.The current IUCN Red List conservation status of S. marmoratus is least concern, indicating a need for further research.