More Like this

1. Three new shrews (Soricidae: Crocidura ) from West Sumatra, Indonesia: elevational and morphological divergence in syntopic sister taxa

   https://doi.org/10.1093/jmammal/gyad126  

   Nations, Jonathan A; Handika, Heru; Mursyid, Ahmad; Darma Busta, Ryski; Apandi; Achmadi, Anang S; Esselstyn, Jacob A (January 2024, Journal of Mammalogy)

   Hawkins, Melissa (Ed.)

   Abstract We describe 3 new species of shrews (Eulipotyphla, Soricidae, Crocidura) from West Sumatra, Indonesia. Two of these taxa were found above 1,800 m on Mt. Singgalang. The third taxon was found above 1,660 m on Mt. Talamau, 65 km northwest of Mt. Singgalang. We also resurrect Crocidura aequicauda based on 2 specimens from Mts. Tujuh and Kerinci, which lie near the border between West Sumatra and Jambi provinces. Several methodological approaches support our findings: linear cranial morphometrics, landmark-based 2D geometric morphometrics, and molecular phylogenetics using both mtDNA and 6 nuclear exons. A multilocus species-tree analysis places the 3 new species and C. aequicauda in a clade with the Javan endemics C. monticola and C. umbra. Although the 2 taxa from Mt. Singgalang are recovered as sister species, 1 is nearly twice the size of the other, and they are divergent in several other morphological characters, such as tail length, cranium size, and pelage color and texture. Recently diverged yet morphologically disparate sister taxa living syntopically in an isolated habitat “island,” like the montane forests of Mt. Singgalang, is unusual in mammals but documented in other Crocidura on neighboring Java and Borneo; these 2 new taxa represent the first known case of this phenomenon on Sumatra. Our results bring the number of Sumatran Crocidura to 10, 9 of which are endemic to the island. All 3 of the new species appear to be endemic to a single mountain and were not detected in similar surveys of nearby mountains. If this local endemism pattern is common, it would indicate that Sumatra’s mammal diversity may be severely underestimated, largely due to the paucity of small-mammal surveys and museum specimens. 

   more » « less
2. Interaction Between the Tethyan and Paleo‐Pacific Tectonic Domains in Southeast Asia: Late Triassic Initiation of an Inward‐Dipping Double Subduction System

   https://doi.org/10.1029/2024TC008762  

   Zhao, Qi; Yan, Yi; Carter, Andrew; Clift, Peter D; Wu, Jonny; Asis, Junaidi Bin; Zhu, Zuofei; Gou, Shihao; Zhou, Yang (August 2025, Tectonics)

   Abstract Interaction between Tethys and the Paleo‐Pacific subduction zones in Southeast Asia during the Mesozoic remains poorly understood. Using new and published zircon U‐Pb and Hf data sets from Borneo (Paleo‐Pacific domain) and Sumatra (Tethyan domain), we propose that isotopically juvenile magmatism was active on both sides of Sundaland due to the initiation of inward‐dipping double subduction during the latest Triassic when Indochina collided with Sibumasu, as evidenced by a pronounced positive shift in zircon εHf(t) values from both Cenozoic sedimentary successions and Mesozoic magmatic rocks in Sumatra and Borneo. From the latest Triassic to Cretaceous, the contrasting positive εHf(t) values ranges between Borneo and Sumatra, with Borneo showing a broad range and Sumatra a narrower variability, imply that the inward‐dipping double subduction system evolved asymmetrically due to differences in slab dip angles between the subducting Meso‐Tethys and Paleo‐Pacific oceanic lithosphere. After 80 Ma, this asymmetric double subduction system was disrupted, marked by the complete cessation of arc magmatism in Borneo while isotopically juvenile magmatism continued on Sumatra. Our findings emphasize that, when compared to the contemporary single‐sided subduction system of the western Meso‐Tethyan domain and the northern Paleo‐Pacific domain, SE Asia developed more juvenile crust due to large‐scale upper plate extension driven by inward‐dipping double subduction. 

   more » « less
3. Light and Scanning Observations on a Denticula species reported from South Africa and endemism of the diatom genus Tetralunata (Rhopalodiales, Bacillariophyceae)

   https://doi.org/10.11646/PHYTOTAXA.652.4.4  

   KOCIOLEK, J PATRICK; GREENWOOD, MEGAN; ROGERS, DILLAN; HAMSHER, SARAH E; MILLER, SCOTT; LI, JINGCHUN; CHANG, AIMEE_CAYE G; TAYLOR, JONATHAN (June 2024, Phytotaxa)

   Denticula costata Hustedt was originally described from fossil material from Sumatra and later assigned to the genus Tetralunata. Although Tetralunata was thought to be endemic to Indonesia, D. costata has been reported from wetwalls from South Africa. This disparity in locality prompted us to investigate the D. costata in South Africa further. D. costata (now T. costata) specimens and the species reported from South Africa were different in size, shape, and structure of the raphe system. These differences, as well as comparisons to other Denticula species, allowed us to determine that the South African specimens have not been described previously. Valve ultrastructure, including the canal raphe, areolae with volate occlusions, and presence/structure of the septa suggest this new species belongs to the genus Tetralunata. This is the first report of Tetralunata from outside of Indonesia. Herein, we describe Tetraluanata schoemanii sp. nov. and its systematic placement close to, but separate from, Epithemia. This first report of Tetralunata from outside of Indonesia, increases our understanding of the genus range and displays a unique biogeographical pattern that warrants further investigation in the future. 

   more » « less
4. The first report of albinism in a Sundaland endemic rodent

   https://doi.org/10.1515/mammalia-2020-0047  

   Nations, Jonathan A.; Mursyid, Ahmad; Darma Busta, Ryski; Adrian, Sah Putra; Handika, Heru; Apandi; Achmadi, Anang S.; Esselstyn, Jacob A. (March 2021, Mammalia)

   Abstract Albinism, a congenital disorder that results in a lack of melanin deposition, is common in domesticated animals but rare in nature. Among the ∼2500 species of rodents worldwide, only 67 have published reports of albinism. Here we report the capture of an albino murid (Muridae: Rodentia) from Mt. Singgalang in West Sumatra, Indonesia. The specimen is an adolescent but sexually mature maleMaxomys hylomyoides, a montane Sumatran endemic. To our knowledge, this specimen represents the first reported albino rodent from Indonesia and Sundaland, and only the second from Southeast Asia. 

   more » « less
5. Effects of the Topography of Sumatra on Tropical Cyclone Formation over the Indian Ocean

   https://doi.org/10.54302/mausam.v74i2.6062  

   Johnson, ProfessorRichard; Ciesielski, PaulE; Fine, CaitlinM; Wang, ChungChieh (March 2023, MAUSAM)

   One-quarter of the world’s tropical cyclones (TCs) occur in the Indian Ocean (IO) basin.The mechanisms for TC initiation in the IO are varied, but one recently discovered process involves the flow around the steep topography of Sumatra.  When the low-level flow impinges on Sumatra, it is blocked and the flow splits under typical environmental stratification.  As a result, wake vortices commonly develop at northern and southern island tips of the island. For the case of easterly flow, these circulationssubsequently move downstream over the IO.  The wake vortices emanating from the island tips are counter-rotating, but since Sumatra straddles the equator, the circulations are cyclonic in both hemispheres and thus have the potential for TC development. Using data from2.5yearsof observations from DYNAMO and YOTC, it is found that approximately 25% of the TCsthat occurred overIO basin during that periodwere initiated by Sumatra-induced wake vortices.Additional analysis of vortex statistics for the period 2008-17 has found that vortex counts are highest near Madden-Julian Oscillation (MJO) phase 1 when low-level easterlies are strongest across southern Sumatra. A secondary peak in vortex formation occurs during MJO phase 4 when low-level westerlies exist near the equator west of Sumatra. The latter finding suggests that MJO-related, low-level westerly surges on the equator impinging on Sumatracontribute to an increase in wake vortex development.  Numerical simulations have shown that circulations farther upstream such aswestern Pacific remnant TCs and the Borneo vortex can influence the development of Sumatra wake vortices and their growth into TCs over the IO. 

   more » « less