Notes on Two Rare Species of Brachyuran Crabs (Families Matutidae and Parthenopidae) From Indonesian Waters with New Distribution Records

Several species of brachyuran crabs in Indonesian waters have not been reported since almost 100 years ago. This research reports a brachyuran crab that is rarely found and one new record in Indonesian waters. This study was conducted in the waters of southern Aru Island and the Malacca Strait using trawls during a cruise held by the Research Institute for Marine Fisheries, Ministry of Marine Affairs and Fisheries, Indonesia.. Our findings were Izanami reticulata, a new record (family Matutidae) from southern Aru Island, and Cryptopadia fornicata (family Parthenopidae) from the Malacca Strait. The two locations are close to where the species were found in previous studies: the Arafura Sea, which is adjacent to the Aru Islands, and the Malacca Strait, which is adjacent to Borneo. It is suspected that the presence of these two species in Indonesia is due to their distribution through sea currents during the pelagic larval stage. This article also provides the specific habitat for both species in Indonesia, which was previously unknown. In addition, this article contributes to strengthening Indonesia as a mega-biodiversity country with an initial compilation of a database of Brachyura in its waters.


INTRODUCTION
The infraorder Brachyura is part of the order Decapoda, which has more than 6,000 species inhabiting land and oceans (Ng et al. 2008).Studies on Brachyura have been conducted intensely in almost all regions of the world.In Indonesia, several expeditions have been carried out to study marine biotas (Table 1).However, information regarding species of the infraorder Brachyura in Indonesia is still relatively scarce (Moosa & Hutomo 2005), several groups of Brachyura have never been reported again, and similarly for the genera of Izanami Galil &P. F. Clark, 1994 andCryptopodia H. Milne Edwards, 1834.Table 1.The series of expeditions to study marine biotas in Indonesia.

MATERIALS AND METHODS
Sampling collection was conducted in July 2015 in the Malacca Strait and in November 2018 in the waters of southern Aru Island during cruise research instigated by the Research Institute for Marine Fisheries, Ministry of Marine Affairs and Fisheries, Indonesia.Four specimens were collected from each location using trawl gear in the morning (8.00-11.00a.m.local time, UTC+7 in Malacca Strait and UTC+9 in southern Aru Island).Samples from each location were preserved in formalin and ethanol 96%, respectively.All four specimens were deposited in the Biosystematics and Animal Ecology Laboratory, Department of Biology, IPB University, with specimen numbers A1 (male), A2 (female) (southern Aru Island), and K40 (male) and K66 (female) (Malacca Strait).Specimens were photographed using a Nikon camera (COOLPIX B700, Nikon, Japan) and then measured using a calliper.Identification at the species level followed Galil and Clark (1994) and Ng and Chiong (1998).Information about the measure was available, Carapace Width (CW) and Carapace Length (CL).CW was measured from both the tip of the posterolateral tooth, and CL was measured from the rostrum until the posterior border of carapace using caliper.(Miers, 1884): Galil and Clark, 1994: pp. 28-31, Figs.5c-5d, Plate 10a-10b

Diagnosis
Carapace circular.Anterolateral surface carapace granulated; frontal median lobe bifid.Surface carapace rough, with six tubercles.Tubercle in cardiac region longest.Posterolateral teeth very short.

Description
Carapace circular, measures of its length and width similar.Surface carapace granulated, particularly in the anterolateral region, with six tubercles present.
Tubercle in cardiac region longest (1.45 mm in female and 1.36 mm in male) and placed between two other smaller tubercles on right and left sides.Carapace smooth posteriorly.Anterolateral margin of carapace has three small teeth, not including inner orbital lobes, tuberculated.Posterolateral teeth rudimentary (very short).Frontal region carapace has three lobes.median lobe (rostrum) bifid, two lateral lobes arranged horizontally (Figs.1A and 1C).
Measurements of both chelipeds similar, 60 mm.Merus short, slightly slender, smooth.Carpus short, swollen, tuberculated.A tuberculate ridge in upper margin of carpus and a sharp tooth at an angle.Palm slightly longer.Its upper margin tridentate, and its size diminishing distally.Merus and carpus of walking legs (I-III) granulated anteriorly.
In abdomen of male, telson slightly longer than its width (Fig. 1B), whereas in female, it an isosceles triangle in shape (Fig. 1D).Penultimate segment widest in both male and female (Figs.1B and 1D).

Remarks
I. reticulata was identified for the first time by Miers (1884) with its type locality in North Australia (Albany Island, Torres Strait), and the scientific name was M. inermis.They were also reported in adjacent waters (Thursday Island and Prince of Wales Island, Arafura Sea) by Miers (1884).This species was found in southern Aru Island in Indonesian waters, which is located near the Arafura Sea.

Diagnosis
Carapace broader than long.Lateral sides of carapace have wide expansions.The branchial, cardiac, and gastric regions are strongly inflated, and the lateroventral carapace depression is deep.

Description
Carapace broader than long, >1.5 times its length, and pentagonal.Lateral sides of carapace have wide expansions concealing all ambulatory legs.Anterolateral margin carapace denticulated (Figs.2A and 2C).Posterolateral margin crenulated and can be seen more clearly in male (Fig. 2B).Posterior margin carapace nearly straight (Figs.2C and 2D), but slightly concave in male specimen (Figs.2A and 2 B) and crenulated.Branchial, cardiac, and gastric regions elevated and form a shallow triangular indentation in centre of carapace (Figs.2A and 2C).
Right cheliped slightly larger than left.Anterior facet of merus consists of three prominent teeth of equal size that denticulated.Distal part of posterior facet of merus has a wing-like expansion that denticulated.Carpus small.Anterior margin of dorsal facet of palm has a slight expansion and denticulated.Posterior margin of dorsal facet of palm has five prominent teeth (Figs.2A-2D).
Ambulatory legs slender; first pair longest, and next diminish in size.Merus has setae (Figs.2B and 2D).
Abdomen granulated in both male and female, and telson triangular (Figs.2B and 2D).

Remarks
The results confirm the occurrence of C .fornicata i n Indonesian w aters.C. fornicata was confirmed as the correct name for C. queenslandi Rathbun, 1918 and C. patula Chiong & P. K. L. Ng, 1998(Ng & Chiong 1998).It was first reported in Borneo, Indonesia as C. fornicata by Miers (1884), but Ng and Chiong (1998) stated (when they reexamined the specimens) that the specimen from Borneo could be C. fornicata because there were no reports about its related species (C.queenslandi and C. patula) from there.Ng and Chiong (1998) also confirmed that C. pentagona Flipse, 1930 from Irian Jaya reported by Flipse (1930) was a juvenile of C. fornicata.

DISCUSSION
In the family Matutidae, initially, the genus Izanami was the genus Matuta, but after a revision by Galil and Clark (1994), Izanami and two other genera (Ashtoret Galil &Clark, 1994 andMebeli Galil &Clark, 1994) emerged as new genera.Of the three genera of the family Matutidae found in Indonesian waters (Matuta, Ashtoret and Izanami), we can see the distribution pattern of these family groups.For the genus Matuta, of the four species found in Indonesia (M.planipes Fabricius, 1798, M. victor Weber, 1795, M. circulifera Miers, 1880, and M. purnama J. C. Y. Lai & Galil, 2007), most are distributed in the coastal areas of western Indonesia (Miers 1880;Galil & Clark 1994;Hanim et al. 2021), except for M. planipes and M.
192 victor, which are also found in eastern Indonesia (Galil & Clark 1994).M. purnama is found only in coastal areas facing the Indian Ocean (ocean coast) (Lai & Galil 2007;Hanim et al. 2021).Although the genus Matuta is generally inhabitant of tropical sandy shores (Lai & Galil 2007), M. victor is also found in the subtropical region of the Mediterranean Sea (invasive species) (Galil & Mendelson 2013;Innocenti et al. 2017).In contrast, the genus Asthoret is primarily distributed in eastern Indonesia (Galil & Clark 1994), and the genus Izanami is also found in eastern Indonesia at 27 m (this study).
Indonesian waters are connected, resulting in Indonesian throughflows (Hasanudin 1998).This situation could result in a wide distribution of marine biotas with a long planktonic larval phase, one of which is in the brachyuran crab (Fisher 2006).One factor influencing these larvae to settle in water is the availability of nursery habitats, such as seagrass meadows (Epifanio & Cohen 2016), mangroves, and corals (Lefcheck et al. 2019).The diversity of these habitats is high in Indonesia.

CONCLUSION
This study recorded a new distribution of I. reticulata in Indonesian waters (as the first report), namely, in the waters of southern Aru Island.This research also confirms the presence of C. fornicata in Indonesia (found in the Malacca Strait), where in previous reports there were descriptions of juvenile individuals.