Mariaplax, Rahayu & Ng, 2014

Rahayu, Dwi Listyo & Widyastuti, Ernawati, 2018, Additions to the Indonesian crab fauna of the genus Mariaplax Rahayu & Ng, 2014, and notes on Hexapus timika Rahayu & Ng, 2014 (Crustacea, Decapoda, Brachyura, Hexapodidae), Zootaxa 4379 (2), pp. 231-246 : 244-245

Key to the species of the genus Mariaplax

1 Pereopods 2̅4 short, merus of P4 less than 3 times as long as broad............................................. 2

- Pereopods 2̅4 long, merus of P4 3 times or more as long as broad.............................................. 9

2 Carapace smooth or pitted............................................................................... 3

- Carapace tuberculate.................................................................................. 4

3 Carapace broad, about 1.7 as broad as long, surface smooth. Merus of P 4 2.8 times as long as broad. Male pleon relatively narrow, telson subpentagonal, 0.8 length of somite 6. G1 bent 60° along two-thirds length, slightly twisted. Female pleon broad, sixth somite 0.8 times length of telson......................... M. narusei Rahayu & Ng, 2014 ( Iriomote Island , Japan)

- Carapace subquadrate, about 1.4 as broad as long, surface pitted. Merus of P 4 2.8 times as long as broad. Male pleon relatively narrow, telson subequal to somite 6, distal margin rounded. G1 bent submedially, strongly twisted. Female unkown............................................................ M. streptophallus Rahayu & Ng, 2014 (Queensland, Australia)

4 Third maxilliped with combined length of dactylus, propodus and carpus longer or subequal than that of merus and ischium; ischium and merus subequal............................................................................. 5

- Third maxilliped with combined length of dactylus, propodus and carpus shorter than that of merus and ischium, ischium longer than merus........................................................................................ 7

5 Mesial and lateral margins of ischium of third maxilliped straight, narrow proximal part short or long................... 6

- Mesial margin of ischium of third maxilliped rounded, lateral margins slightly oblique; narrow proximal part relatively long. Female pleon broad, telson subequal to length of somite 6, male unknown..................................................................................................... M. aspera Ng & Rahayu, 2015 (Lombok, Indonesia)

6 Third maxilliped with width of exopod 0.4 times width of ischium, narrow proximal part of ischium short. Male pleon relatively narrow, telson subtriangular, 1.2 length of somite 6. G1 S-shaped. Surface of chelipeds and P2̅P4 without short, stiff setae. Female pleon relatively broad, telson 0.8 times length of somite 6................................................................................................. M. anfracta (Rathbun, 1909) (Gulf of Thailand, Malaysia)

- Third maxilliped with width of exopod 0.5 times width of ischium, narrow proximal part of ischium long. Surface of chelipeds and P2̅P4 with short, stiff setae. Female pleon relatively broad, telson subequal to length of somite 6. Male unknown......................................................................... M. hispida n. sp. (Jakarta Bay, Indonesia)

7 P4 with propodus slightly shorter than carpus............................................................... 8

- P4 with propodus much shorter than carpus, merus 2.9 as long as broad. Male pleon relatively wide, telson rounded, 0.7 length of somite 6. G1 stout, slightly S shaped. Female pleon relatively narrow, telson 0.8 length of somite 6.................................................................. M. granulifera (Campbell & Griffin, 1978) (Moreton Bay, Australia)

8 Merus of P4 2.6 as long as broad. Female pleon relatively broad, telson 0.8 length of somite 6. Male unknown.............

............................................................. M. galaxea Rahayu & Ng, 2014 ( Singapore strait) - Merus of P4 2.8 as long as broad. Female pleon relatively narrow, telson 0.7 length of somite 6. Male pleon relatively narrow, telson elongate, distal margin rounded, subequal to somite 6. G1 slender, slightly S shaped........................................................................................ M. ourabay Rahayu & Ng, 2014 (Oura Bay, Japan)

9 P4 with visible longitudinal groove on lateral surface........................................................ 10

- P4 with barely or not visible longitudinal groove on lateral surface............................................. 15

10 Chelipeds, P2̅P4 pubescens............................................................................ 11

- Chelipeds not pubescens, P2̅P4 with setae................................................................ 12

11 Merus of third maxilliped as long as ischium. Male pleon relatively narrow, telson with distal margin rounded, as long as somite 6. Male G 1 slightly curved medially, tapering distally ended in blunt tip. Female pleon relatively narrow, telson as long as somite 6....................... M. daviei Rahayu & Ng, 2014 ( Australia: Port Jackson , New South Wales; Tasmania)

- Merus of third maxilliped shorter than ischium. Female pleon relatively broad, telson distinctly longer than somite 6. Male unknown.................................................. M. mica Rahayu & Ng, 2014 (Bohol sea, Philippines)

12 Merus of P4 3 times as long as broad, with sparse setae...................................................... 13

- Merus of P4 more than 3 times as long as broad............................................................ 15

13 Male pleon relatively narrow, telson rounded subequal to somite 6. G1 stout, S-shaped distally, directed anterolaterally, distal part tapering, twisted. Female pleon relatively narrow, telson 0.8 times length of somite 6.......................................................................................... M. chenae Rahayu & Ng, 2014 (South China Sea)

- Male pleon relatively narrow, telson rounded subequal to somite 6. G1 slender, S-shaped from midlength, distal part tapering, not twisted. Female unknown........................... M. sinensis Rahayu & Ng, 2014 (Bohai Gulf, East China Sea)

14 Carapace relatively broad, 1.6 as broad as long, with closely spaced tubercles, P2̅P4 tomentose. Exopod of third maxiliped 0.3 times width of ischium. Male pleon relatively narrow, telson subpentagonal, 0.7 times length of somite 6. Female unknown........................................................ M. propinqua Rahayu & Ng, 2014 (Tonkin Gulf, China)

- Carapace 1.5 as broad as long, with widely-spaced tubercles. P2–P4 with sparse, long setae. Exopod of third maxilliped 0.4 times width of ischium. Female pleon relatively narrow, telson as long as somite 6. Male unknown........................................................................................... M. pitrai n. sp. (Jakarta Bay, Indonesia)

15 Carapace squarish. No longitudinal groove on lateral surface of P3. Ischium of third maxilliped as long as broad. Merus of P4 about 3.4 as long as broad. Male pleon relatively narrow, telson subpentagonal, about same length as somite 6. G1 bent 90° at midlength. Female unknown................................. M. cyrtophallus Rahayu & Ng, 2014 (Papua, Indonesia)

- Carapace rectangular. Distinct longitudinal groove on lateral surface of P3....................................... 16

16 Carapace 1.6 as broad as long, entirely covered by tubercles. Merus of P4 4.3 times as long as broad. Male pleon broad, short, 3̅6 somites fused, telson subtriangular. G1 bent 90° at midlength. female unknown............................................................................................ M. secus Rahayu & Ng, 2014 (Madang, New Guinea)

- Carapace 1.7 as broad as long, covered by tubercles except on gastric region. Merus of P4 3.3 times as long as broad. Female pleon relatively broad, telson 1.5 as long as somite 6. Male unknown........... M. sundaica n. sp. (Sunda Strait, Indonesia)