Morphological and Molecular Characterization of Diplogasteroides sp., a Cryptic Population of the Haslacheri Group (Diplogastridae), and Parasitorhabditis terebranus (Rhabditidae) from Korea

Abstract

Diplogasteroides sp., a cryptic population of D. haslacheri, and Parasitorhabditis terebranus were reported from the frass of Monochamus alternatus galleries in dead Pinus thunbergii for the first time in Korea. Females and males are morphologically characterized and their linked DNA barcodes (18S-rRNA, 28S-rRNA, ITS-rRNA and COI) supplied. Females and males of the two species from Korea conform to the original species descriptions from Europe and the USA, with variations in a few details in morphometrics. Specifically, Diplogasteroides sp. is morphologically very similar to D. haslacheri. However, it cannot be designated as D. haslacheri due to the existence of cryptic species complex within the haslacheri group (D. haslacheri, D. asiaticus, D. nix, D. andrassyi, and D. carinthiacus), a condition requiring hybridization studies to test species identity within the group. Based on analysis of COI sequences, differences among these cryptic species are evident. Thus, in addition to hybridization tests, the COI might be a powerful DNA barcoding marker for the precise identification of these cryptic species within the genus. Additionally, this is the first molecular characterization of P. terebranus, and the species is herein recorded for the first time outside its type locality.

A Revision of the Phylogeny of Helicotylenchus Steiner, 1945 (Tylenchida: Hoplolaimidae) as Inferred from Ribosomal and Mitochondrial DNA

“…Polymerase chain reaction (PCR) was performed with a PCR cycler (T100, Bio-Rad, Hercules, CA, USA), the PCR program with specific primers being set as follows: initial denaturation at 95°C for 5 min, 35 cycles at 95°C for 30 s, followed by an annealing step at 58°C for 30 s (S-ITS1/Vrain2R), 54°C for 40 s (COIHF/COIPR), 56°C for 40 s (COIF5/COIR9); 72°C for 60 s (S-ITS1/Vrain2R), 72°C for 80 s (COIHF/COIPR and COIF5/COIR9), and finally one cycle at 72°C for 5 min (COIHF/COIPR) and 72°C for 10 min (S-ITS1/Vrain2R and COIF5/COIR9). The cycle for D2A/D3B and JB3/JB5 primer sets was as described by Mwamula et al (2023a) while the thermal profiles for TW81/AB28, 988F/1912R and 1813F/2646R primer sets were set as detailed by Mwamula et al (2023b) . The PCR products were purified using a PCR purification kit (Qiagen, Hilden, Germany) and quantified using a quickdrop spectrophotometer (Molecular Devices, San Jose, CA, USA).…”