Campylaimus minutus Fadeeva, Mordukhovich & Zograf, 2016

Holovachov, Oleksandr, 2019, New and known species of the genus Campylaimus Cobb, 1920 (Nematoda: Araeolaimida: Diplopeltidae) from North European marine habitats, Biodiversity Data Journal 7, pp. 46545-46545 : 46545

Campylaimus minutus Fadeeva, Mordukhovich & Zograf, 2016

Materials

Type status: Other material. Occurrence: catalogNumber: SMNH-177090 ; individualCount: 4; sex: female; Location: waterBody: Skagerrak; country: Sweden; locality: Bratten ; minimumDepthInMeters: 139; maximumDepthInMeters: 153; verbatimLatitude: 58°34,19'N; verbatimLongitude: 10°38,20'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2012; month: 10; day: 12; habitat: Soft bottom Type status: Other material. Occurrence: catalogNumber: SMNH-177091 ; individualCount: 1; sex: female; Location: waterBody: Skagerrak; country: Sweden; locality: Bratten ; minimumDepthInMeters: 139; maximumDepthInMeters: 153; verbatimLatitude: 58°34,19'N; verbatimLongitude: 10°38,20'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2012; month: 10; day: 12; habitat: Soft bottom Type status: Other material. Occurrence: catalogNumber: SMNH-177092 ; individualCount: 1; sex: male; Location: waterBody: Skagerrak; country: Sweden; locality: Gullmarsfjord, Kristineberg-Lysekil ; minimumDepthInMeters: 53; maximumDepthInMeters: 53; verbatimLatitude: 58°15,73'N; verbatimLongitude: 11°26,10'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2014; month: 8; day: 14; habitat: Mud Type status: Other material. Occurrence: catalogNumber: SMNH-177093 ; individualCount: 1; sex: female; Location: waterBody: Skagerrak; country: Sweden; locality: Gullmarsfjord, Kristineberg-Lysekil ; minimumDepthInMeters: 53; maximumDepthInMeters: 53; verbatimLatitude: 58°15,73'N; verbatimLongitude: 11°26,10'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2014; month: 8; day: 14; habitat: Mud Type status: Other material. Occurrence: catalogNumber: SMNH-177124 ; individualCount: 3; sex: 2 females, 1 male; Location: waterBody: Skagerrak; country: Sweden; locality: Bratten ; minimumDepthInMeters: 139; maximumDepthInMeters: 153; verbatimLatitude: 58°34,19'N; verbatimLongitude: 10°38,20'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2012; month: 10; day: 12; habitat: Soft bottom Type status: Other material. Occurrence: catalogNumber: SMNH-177125 ; individualCount: 1; sex: female; Location: waterBody: Skagerrak; country: Sweden; locality: Bratten ; minimumDepthInMeters: 139; maximumDepthInMeters: 153; verbatimLatitude: 58°34,19'N; verbatimLongitude: 10°38,20'E; Identification: identifiedBy: O. Holovachov; dateIdentified: 2018; Event: year: 2012; month: 10; day: 12; habitat: Soft bottom

Description

Measurements. Table 1 . Adult. Figs 4 , 5. Cuticle without longitudinal striation. Space between dorsal and ventral limbs of amphid not developed. Lateral alae narrow, appearing externally as two straight lines encompassing entire length of amphid. It originates at level with anterior edge of amphid, extends posteriorly as two lines parallel and very close to ventral limb of amphid and ends close to tail tip by merging with posterior end of ventral limb of amphid ( Fig. 5 d). Secretory-excretory pore opens posterior to cardia, at level with anterior part of intestine. Tail with conoid terminal part. Male. Anteriormost edge of amphid positioned at level with oral opening. Dorsal limb of amphid extends for a short distance posteriorly, equal to 2.2 labial region diameters in length. Ventral limb of amphid extends along entire body to terminal part of tail. Ventral limb of the amphid is 1.0-1.5 wider than dorsal limb. Spicules with rounded manubrium and subcylindrical, arcuate shaft. Gubernaculum platelike, without apophysis. Precloacal supplements indistinct/absent. Female. Anteriormost edge of amphid positioned just posterior to or at level with oral opening. Dorsal limb of amphid extends for a short distance posteriorly, equal to 1.6-2.6 labial region diameters in length. Ventral limb of amphid extends along entire body to terminal part of tail. Ventral limb of amphid is 1.5-2.0 wider than dorsal limb. Vagina straight ( Fig. 5 c). One pair of ventrosublateral setae located along the middle of tail and one pair of sublateral setae located subterminally.

Diagnosis

Body 0.36-0.56 mm long; cuticle without longitudinal striation; anteriormost edge of amphid at level with oral opening; dorsal limb of amphid equal to 2.2 labial region diameters in male, 1.6-2.6 labial region diameters in female; ventral limb of amphid extends towards terminal part of tail in both female and male; ventral limb of amphid is 1.0-2.0 times wider than dorsal limb; interamphideal space absent; secretory-excretory pore opens posterior to cardia; spicules 16 µm long; precloacal supplements indistinct; tail equal to 4.1-6.0 anal body diameters in length, with conoid terminal part.

Taxon discussion

Recent specimens are nearly identical with the type populaiton of C. minutus from the Sea of Japan ( Fadeeva et al. 2016) in qualitative and quantitative characters. C. minutus was originally distinguished from C. gerlachi in having relatively shorter cephalic setae (equal to 20% vs. 50% of the labial region width in length) and relatively shorter tail (<5 vs.>5 anal body diameters in length). As pointed below in the discussion, length of cephalic setae is often impossible to measure correctly, while the relative length of the tail in the C. gerlachi from Kiel Bay is exactly 5 ( Gerlach 1950). Two species can however be distinguished from each other by the shape of the tail (clavate in C. gerlachi vs. conoid in C. minutus , see also Figure 5B in Fadeeva et al. (2016)) and in the position of the posterior end of the amphid (at a distance from the tail terminus in C. gerlachi vs. close to the tail terminus in C. minutus ). Female specimen depicted on the Figures 5F-G in Fadeeva et al. (2016) could belong to C. gerlachi instead.

Figures

Figure 4. Campylaimus minutus Fadeeva, Mordukhovich & Zograf, 2016 (scale bars = 20 µm, PIJ = pharyngo-intestinal junction / cardia, EP = secretory-excretory pore): a: female tail; b: female pharyngeal region; c: male pharyngeal region; d: male caudal region.