Tuesday, February 12, 2019

[Mollusca • 2018] Microparmarion exquadratus Bringing the Lab to the Field: A New Lowland Microparmarion Semi-slug (Gastropoda: Ariophantidae) from Borneo, described and DNA-barcoded in the Forest

Microparmarion exquadratus 
 Schilthuizen, Clavera, Khoo, Bondar, Elder, Bouma, Eddington, Reisinger, Cosentino, Rossato & Delledonne, 2018 

 DOI:  10.1093/mollus/eyy052  

Cybertaxonomy and portable DNA sequencing now make it possible for citizen scientists to be engaged in the discovery and description of new taxa. We here provide a proof of principle. A new semi-slug, Microparmarion exquadratus n. sp. (Ariophantidae) was discovered during a field course in tropical biology in Borneo for citizen scientists. The new species is the first lowland representative of its genus. It differs from other (high-elevation) Microparmarion species by its size, pigmentation on head and tail, and shape of dart sac and receptaculum. As part of the course programme, the participants prepared a taxonomic description and illustrations, and used the mobile genomic laboratory of the course to obtain DNA barcodes. As far as we are aware, this is the first time a new invertebrate species has been described both morphologically and genetically from the field.

 External morphology of (presumably) adult Microparmarion exquadratus n. sp., syntype in living state as photographed in the field in Tawau Hills Park, Sabah.

 DOI:  10.1093/mollus/eyy052  

Microparmarion exquadratus n. sp.
 DOI:  10.1093/mollus/eyy052  

Microparmarion exquadratus Schilthuizen et al., new species

Etymology: The name was chosen at a naming and voting session during the taxon expedition and refers to the ‘squad’ of participants that jointly sampled this species during night-time walks in the forest. The taxonomic authority for this species is attributed to all authors of this paper. Following Article 51 C of the Code (ICZN, 1999), the species can be referred to as Microparmarion exquadratus Schilthuizen et al., 2018, provided the full citation of this publication appears in the bibliography or elsewhere in the referring work.

Diagnosis: Among Microparmarion species of Borneo, M. exquadratus is characterized by small size (less than half the size of M. pollonerai and M. simrothi), three dark longitudinal stripes on head (shared with M. simrothi, but lacking in M. pollonerai and M. litteratus), dark dorsal stripe on tail, kink in dart sac (shared with M. pollonerai) and reduced receptaculum.

Remarks: In colour pattern, M. exquadratus is somewhat similar to a Microparmarion species found at an elevation of 1,200 m asl in Long Pa Sia, southwestern Sabah, and also to a species photographed (but not collected) at 1,000 m asl in Penrissen, Sarawak (Schilthuizen, 2017). However, it is unlikely to be conspecific with either, because it differs in colour pattern (the Penrissen specimen has two, rather than three, head stripes, and the Long Pa Sia specimen lacks the black markings on the mantle lobes) and is larger in size. For the time being, therefore, we consider the M. exquadratus to be restricted to Tawau Hills Park. Our phylogenetic reconstruction (Fig. 5), although primarily intended to assess the genetic distinctness of the new species, also suggests that the genus Microparmarion consists of multiple clades that are not fully congruent with named species. We therefore recommend that the genus be subjected to a formal revision.

We must also stress that our work was conducted under several limitations and constraints. It was part of a full 10-day field course schedule, carried out by untrained citizen scientists in a field station with limited equipment and erratic electricity supply. Specimens could not be exported. Consequently, the extent of our work is less than is customary for descriptions of new semi-slug species: we sequenced only three individuals and dissected only one. Also, all individuals were obtained from a very small geographic area. Nonetheless, the genetic and morphological features are sufficient to recognize the species unambiguously.

Menno Schilthuizen, Anna Pazos Clavera, Min Sheng Khoo, Carin A. Bondar, Charles H. S. Elder, Aglaia M. Bouma, Taly D. Eddington, Christian Reisinger, Emanuela Cosentino, Marzia Rossato and  Massimo Delledonne. 2018. Bringing the Lab to the Field: A New Lowland Microparmarion Semi-slug (Gastropoda: Ariophantidae) described and DNA-barcoded in the forest. Journal of Molluscan Studies. eyy052.  DOI:  10.1093/mollus/eyy052  

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