Sermyla carbonata, (REEVE, 1859)

Lentge-MAAss, Nora, Neiber, Marco T., Gimnich, France & Glaubrecht, Matthias, 2021, Evolutionary systematics of the viviparous gastropod Sermyla (Gastropoda: Cerithioidea: Thiaridae), with the description of a new species, Zoological Journal of the Linnean Society 192 (3), pp. 736-762 : 755-756

SERMYLA CARBONATA ( REEVE, 1859)

( FIGS 1 U –AB, 4, 11E, F)

Melania carbonata Reeve, 1859 : pl. 13, fig. 88. Type locality: Not given. Melania venustula Brot, 1877: 331 , pl. 34, fig 5, 5a.

Type locality: ‘ Port Denison, Nov. Holl.’ ( Port Denison , Western Australia) .

Sermylasma prognata Iredale, 1943: 208 . Type locality: Victoria River , North Australia.

Type material: Melania carbonata : two syntypes ( BMNH 20010762 ) . Melania venustula : six syntypes ( MHNG 121205 ) . Sermylasma prognata : holotype ( BMNH 1857.9.30.8) .

Additional material examined: Australia: Western Australia: West side of Cape Range, Bundara Sinkhole, 225°S 113°46´E ( WAM BES 10049 w, 10050 w, 13049 w, 13050 w). Northern Territory: Howard Springs 6 km E of Stuart highway (station Northern Territory 10) ( AMS C.110490, C.427959 w) ; Howard Springs, 12°27.345´S 131°03.146´E ( ZMB 106593 w, 106700 w, 127660 w) ; Howard Springs Creek, 12°27.268´S 131°03.108´E ( ZMB 106595 w, 107228 w, 107627 w, 107630 w) ; Spring creek at Howard Springs, 12°27.553´S 131°03.069´E ( ZMB 107979 w, 127659 w, 127660 w) ; Berry Springs, 48 miles SW of Darwin ( QM 5624, 5625) ; Berry Springs, SE of Darwin, 12 °42.111´S 130 °59.875´E ( ZMB 107210 w, 107544 w, 107545 w, 127634 w) ; Black Jungle Springs, 13°3´S 132°9.86´E ( VK 25843) ; Katherine River, 3 miles W of Katherine ( QM 5621) ; SE of Katherine, creek just before turn off from Roper to Elsey Falls ; Stevie´s Hole at Waterhouse River, Elsey National Park, 15°55.782´S 133°8.732´E ( ZMB 106682) ; Little Roper River, at crossing, 14°55.581´S 133°07.176´E ( ZMB 106629 w, 106678 w, 107236 w, 107561 w, 107562 w) ; Little Roper River at crossing, south bank, lilly pond, 14°55.589´S 133°07.137´E ( ZMB 127515 w, 127639 w) ; Little Roper River at crossing, north bank, among palms, 14°55.630´S 133°07.105´E ( ZMB 127640 w, 127641 w) ; Roper River ( QM 8476; AMS C.109742) ; Roper River, old bridge crossing at Mataranka Homestead, 14°55.5´S 133°6.5´E ( AMS C.317322 w, C. 317323 w, C. 317325 w) ; Roper Creek near junction with Waterhouse Creek near Mataranka at road crossing ford-Station Northern Territory 10, 14°55.74´S 133°7.06´E, stagnant pool; roots alongside of river, not in max flow of water ( AMS C.323808 w) ; Waterhouse River, Mataranka tourist resort ( QM 5158; VK 0958) ; Roper River, at Botanic Walk, 14°56.126´S 133°08.532´E ( ZMB 127642 w) ; Roper River, at 4-mile point, 14°56.120´S 133°10.069´E ( ZMB 127644 w) ; Wabalarr, at Roper River, 14°56.028´S 133°10.444´E ( ZMB 107615 w, 107616 w, 107618 w, 127645 w) ; Mulurark, at Roper River, 14°56.763´S 133°12.614´E ( ZMB 107621 w, 127646 w) ; Roper River, at Jalmurark Camp Ground, 14°57.158´S 133°13.29´E ( ZMB 106676 w, 107229 w, 107557 w, 107558 w) ; Roper River, between Mataranka Falls and Jalmurark campground, 2 km below Jalmurark (downstream), 14°57.515´S 133°14.275´E ( ZMB 127638 w) ; Roper River, at Mataranka, 14°56.771´S 133°12.609´E ( ZMB 106623 w) ; E of Mataranka between Elsey Station and Elsey falls, 14°57.5´S 133°18.333´E ( AMS C.322659) ; Salt Creek at junction to Roper River, 14°57.453´S 133°15.095´E ( ZMB 127635 w) ; Elsey Creek on Roper Highway, 15°00.627´S 133 °14.417´E ( ZMB 107231 w, 127649 w, 127650 w) ; Salt Creek, near Elsey Creek, at crossing of Roper Highway, 15°0.703´S 133°14.417´E ( ZMB 107230 w, 127647 w, 127648 w) ; Warloch Ponds on Elsey Creek, near Old Stuart Highway, Elsey Station, Mataranka Area, 16°05.042´S 133°07.258´E ( ZMB 192019 w, 127657 w, 127658 w) ; Roper Bar, Roper River, 14°42.816´S 134°30.501´E ( ZMB 192017 w, AMS C.323807 w) ; Mumpumapu waterhole, Phelp River drainage, Numbulwar-Roper road, Mumpumapu Outstation, Arnhem Land, 14°22.59´S 135°19.34´E ( AMS C.461353 w) ; 8 km NE of Towns River Crossing, 14°59.82´S 135°16.28´E ( ZMB 192016 w, 192018 w) ; Towns River, E of Mataranka, 14°42.94´S 134°30.44´E, below road crossing (Station Northern Territory 15) ( AMS C.317337 w) ; Roper Bar, Roper River, Gulf of Carpentaria, 14°42.46’S 134°30.30’E ( VK 26347, VK 25911) ; Roper River, SW section of Gulf of Carpentaria, 14°42’S 134°05’E ( NTM P15921) ; Towns River, at crossing with Roper Highway, 15°02.570´S 135°12.718´E ( ZMB 127651 w) ; Towns River, backwater at junction with creek, 14°59.999´S 135°17.030´E ( ZMB 127654 w, 127655 w) ; Foelsche River, 16°12.628´S 136°53.034´E ( ZMB 107232 w) ; Queensland: Bynoe River ( ZMB 106712 w, MCZ 173385) ; 4.5 km NW of Normanton, road from Normanton to Karumba (saline ponds), 17°39.43´S 141°06.03´E ( VK 26.356, ZMB 106713 w) ; Norman River, billabong 1 km N of Normanton, 17°39.712´S 141°06.154´E ( ZMB 107235 w, 127656 w) ; Billabong ca. 1 km from Norman River towards Kurumba on Kurumba Road, 17°39.64´S 141 6.1´E, on sand and mud; Ivanho crossing, Ord River, 7.5 miles NW of Kununurra ( QM 5627) ; Gregory River, Riversleigh Station ( QM 64501) ; Townsville, northern Queensland, crawling on algal slime at the water edge, smaller, i.e. older artificial lake, 19°16´S 146°49´E, ( NTM P27449) ; Currejong, Townsville, northern Queensland, 19°16´S 146°49´E, ( NTM P27448) ; Port Denison ( ZMB 59156) ; North of Hughenden, Soda Valley Creek, 20 22´S 150°32´E ( AMS C.58393) ; Peanmnga Spring, west of Mt. Whelan, 22°26´S 138°48.30´E, ( AMS C.338667) ; Caloundra ( QM 64454) ; Fitzroy River at Rockhampton, 23°22´S 150°32´E, ( AMS C.58393). And initially as S. cf. riquetii from Australia: Northern Territory: Towns River, E of Mataranka, below road crossing, 14°42.94´S 134 °30.44´E, ( AMS C.317336; station Northern Territory 15, 5781). Queensland: Lizard Island ( BMNH 1854.10.28.32): Kapoh Cove Beach, North Point ( AMS) ; Buchans Point, N of Cairns ( AMS) ; Port Curtis ( AMS) ; Caloundra, brackish water from Twoway Creek ( AMS C.42010).

Diagnosis: Shell up to 34 mm high (exceptional 41 mm), aperture reaching approximately one-third of total shell height; opisthocyrt ribs and basal spiral grooves usually well developed, sometimes faint to rarely absent. Crawling juveniles with up to seven shell whorls are released from the subhaemocoelic brood pouch of the female.

Description

Shell ( Fig 1U –AB): Shell highly polymorphic, but generally slender, with up to ten whorls and with a mean height of about 21 mm (occasionally over 30 mm; or even exceptionally 41 mm (Roper River population) and a maximum of 11 whorls); light to dark brown, often with darker brown blotches, mainly on the body whorl. Basal part of body whorl with spiral grooves and ridges, the axial opisthocyrt ribs on upper part of body whorl and spire more or less pronounced. Shells from Western Australia, Bundara Sinkhole ( Fig. 1X ) with lightest shell colour and without blotches, with less-developed axial ribs, but clearly visible radial ridges in the basal part of the last whorl. Shells from Howard Springs ( Fig. 1Y ) medium to dark brown and darker colour pattern, axial ribs and spiral sculpture pronounced. Shells from Roper River ( Fig. 1Z , AA) relatively large, with medium brown coloration and dark patterns on all whorls; axial ribs more or less pronounced, radial ridges and grooves on basal part of body whorl always pronounced (most similar to the type material) of M. venustula ( Fig. 1V ). Shells from the Gulf of Carpentaria ( Fig. 1 AB) darker in comparison to the former, much smaller compared to all the other S. carbonata populations, with a pronounced radial spiral sculpture; upper tip of shell usually corroded.

Reproduction: Brood pouches of female S. carbonata filled with about 150 shelled juveniles of different ontogenetic stages, i.e. the species has a euviviparous reproductive strategy.

Juvenile shell ( Fig. 5B ): Juvenile shells of S. carbonata as diverse as the adult shells, with up to seven whorls; mostly with clearly visible axial ribs, crossed by weak spiral grooves. Only juvenile shells from Western Australia (Bundara Sinkhole) lacking spiral grooves, but with axial growth lines. Most juveniles ~ 1 mm (sometimes> 3mm). Only between 3.7% (Western Australia) and 7.9% (Howard Springs) of the shells are 1.1 mm or more in shell height.

Radula ( Fig. 11E, F ): The radula of S. carbonata corresponds to those typical for other Thiaridae ( Glaubrecht et al., 2009) . The approximately nine denticles along cutting edge of rachidian teeth consistently more distinctly cusped than in other thiarids, with sharply pointed denticles. Central denticle of the lateralia also narrow and sharply pointed, flanked on either by three to four pointed denticles. Marginalia with nine to ten denticles.

Ecology: Sermyla carbonata is not only known from lower courses of rivers and streams (e.g. Towns River), but also further inland in the Northern Territory at localities with partial saline conditions. Some areas of the Roper River drainage system, for example, at Salt Creek, are almost marine-like in their salt content dissolved from sedimentary rocks (see: Glaubrecht et al., 2009).

Distribution: Sermyla carbonata is distributed mainly in the northern part of the Australian continent, but restricted to the Timor Sea and Gulf of Carpentaria drainages. In addition to the distribution revealed in Glaubrecht et al. (2009), two new localities have recently been discovered and verified with the use of molecular genetics (see below): (1) Berry Springs, to the south-west of Darwin, Northern Territory, at a highly isolated location and (2) even further to the west, the isolated population from Bundara Sinkhole in Western Australia. On the basis of shell morphology and biometry, shells initially sorted to S. cf. riquetii were assigned to S. carbonata . This extends the distribution into the Coral Sea/Jardinian–Krefftain drainage system on the basis of historical shell samples.

Remarks

Glaubrecht et al. (2009) described this taxon in detail under the available name S. venustula Brot, 1877 (see also: Maass & Glaubrecht, 2012). However, this species name cannot be used because M. carbonata Reeve, 1859 , which we consider to be conspecific, has priority. The type locality of M. carbonata was not given in the original publication, but later stated to be from Port Essington ( Australia, Northern Territory, Cobourg Peninsula) by Brot (1876: 153) and Smith (1882: 259). The name S. prognata Irdale, 1943 cannot be regarded as a replacement name (although stated to be a nom. nov.) for M. venustula Brot, 1874 , because Iredale (1943: 208) considered both to be separate species. Sermyla prognata was based by Iredale (1943: 208) on a single specimen [with reference to a description and figure of that specimen by Smith (1882: 260, pl. 5, fig. 10)], which has, therefore, to be considered the holotype. Sermyla carbonata can be distinguished from S. riquetii and S. kupaensis by the higher spire and often larger and variable shell. From S. kupaensis it can also be distinguished by the different reproductive strategy, i.e. euviviparity, with crawling juveniles released from the brood pouch of female S. carbonata , compared to ovoviviparity, with veliger larvae released from the brood pouch of female S. kupaensis .

Figures

Figure 1. A–AB, shell morphology of Sermyla: A–O, Sermyla riquetii; P–T,Sermyla kupaensis; U–AB, Sermyla carbonata.A, syntype of Sermyla riquetii (Grateloupe, 1840), ‘Batavia’ (BMNH 1907.11.22.40); B, syntype of Sermyla riquetii (Grateloupe, 1840), ‘Batavia’ (BMNH 1907.11.22.41); C, syntype of Melania harpula Dunker, 1844 (ZMB 109669); D, syntype of Melania mitra Dunker, 1844 (ZMB 109670); E, original drawing of Melania semicostata Philippi 1847; F, syntype of Melania tornatella Lea & Lea, 1851 (BMNH 1978155); G, syntype of Melania sculpta Souleyet, 1852 (BMNH 1854.7.24.381); H, holotype of Sermyla kowloonensis Chen, 1943 (USNM 48041); I, S. riquetii from Bali, Gumbrih River (ZMB 106474-3); J, S. riquetii from Thailand, Puek Tian Beach (ZMB 107883-11); K, S. riquetii from Thailand, Perchaburi (ZMB 127817-2); L, S. riquetii from Thailand, Samut Songkhram (ZMB 127818-2); M, S. riquetii from Vietnam, Hue (ZMB 114421–5); N, S. cf. riquetii from Australia: QLD, Caloundra (AMS C.3215-1); O, S. cf. riquetii from Australia: QLD, Caloundra (AMS C.3215-2); P, holotype of Sermyla kupaensis from Indonesia, Kupa River (MZB Gst. 12.191); Q, paratype of Sermyla kupaensis ZMB 191388-4); R, paratype of Sermyla kupaensis (ZMB 191388-10); S, paratype of Sermyla kupaensis (ZMB 191388-5); T, paratype of Sermyla kupaensis (ZMB 191388-7); U, syntype of Sermyla carbonata (Reeve, 1859), ‘Port Essington’ (BMNH 2001.0762); V, syntype of Melania venustula Brot, 1877, ‘Port Denison’ (MNHG, no number); W, holotype of Sermylasma prognata Iredale, 1943, Australia, Victoria River (BMNH 1857.9.30.8-1); X, S. carbonata, Australia: Bundara Sinkhole (BES 10048); Y, S. carbonata, Australia, Howard Springs (ZMB 107630–2); Z, S. carbonata, Australia, Roper River (ZMB 107616-1); AA, S. carbonata, Australia, Roper Bar (ZMB 192017-1); AB, S. carbonata, Australia, Norman River (107209-5).

Figure 5. Morphological differences of Sermyla kupaensis, S.riquetii and S. carbonata populations. A, boxplots for the height measurements of Sermyla kupaensis, S.riquetii and S. carbonata from the different sampling locations and river systems. Five-pointed star: syntypes of S. riquetii; six-pointed stars: syntypes of M. venustula; triangle tip down: holotype of S. prognata; nine-pointed star: syntypes of S. carbonata. B, boxplots for the total amount of juveniles inside the brood pouch of S.riquetii and S. carbonata from different sampling locations and drainage systems, as well as a veliger larva from Sermyla kupaensis for comparison.

Figure 11. Anatomy of the radula in Sermyla. A, rachis and lateralia of Sermyla kupaensis (ZMB 191388). B, marginalia of Sermyla kupaensis (ZMB 191388). C, rachis and lateralia of S. riquetii (BMNH 2403). D, marginalia of S. riquetii (BMNH 2403). E, rachis and lateralia of S. carbonata (ZMB 106700). F, marginalia of S. carbonata (ZMB 106700).