Bestiolina sarae Dorado-Roncancio & Gaviria

Dorado-Roncancio, John, Gaviria, Santiago, Bernal-De La Torre, Luis & Ahrens, Michael J., 2019, A new species of Bestiolina (Crustacea, Copepoda, Calanoida, Paracalanidae) from coastal waters of the Colombian Pacific, including a worldwide key for the identification of the species, ZooKeys 846, pp. 1-18 : 1

Bestiolina sarae Dorado-Roncancio & Gaviria sp. n.

Material examined.

Holotype: Adult female (MAKURIWA INV-CRU8991) dissected on a slide, mounted in Entellan. Allotype: male dissected on a slide (MAKURIWA INV-CRU8992), mounted in Entellan. Paratypes: two females (NHMW 26309 and 26310), each one dissected on three slides and mounted in lactophenol, one female (NHMW 26311) dissected and mounted in one slide; six females (NHMW 26312) undissected and preserved in ethanol; one female and two males undissected, preserved in ethanol+glycerine (MAKURIWA INV-CRU8993 y 8994). Material was collected by L. Bernal, M. Ahrens and J. Dorado-Roncancio, as follows: holotype and allotype on 30/09/2016 near Buenaventura harbor (03°53'49.054"N, 077°03'44.3"W), paratypes on 26/07/2017 in the Bahía Málaga (03°55'30.759"N, 077°20'56.48"W).

Etymology.

The new species is named in honour of Sara Dorado, an important member of the family of the first author, who passed away one year before the discovery of the species. The name of the species is a feminine noun in genitive singular.

Type locality.

Near Buenaventura harbor (03°53'49.054"N; 077°03'44.3"W) (Fig. 1), Eastern Pacific Ocean, Colombia. At the type locality, the waters are characterized as coastal and estuarine. The type locality belongs to the Buenaventura natural ecoregion of the Colombian Pacific according to the classification of Diaz and Acero (2003). The area is characterized by bays, with an average depth between 12 m and 15 m, and tectonic estuaries, which include a wide variety of habitats such as sandy and rocky beaches, mudflats, large areas of high-productivity mangroves, sandstone cliffs and soft-sediment floodplains. Many rivers and streams empty into the sea, bringing high amounts of sediments and causing variations in the physical and chemical conditions of the waters ( Lazarus-Agudelo et al. 2007, Betancourt and Portela et al. 2011). Precipitation in the region is very high (> 5000 mm/y) ( Dimar 2002). Water chemistry can be characterized as follows: surface temperature ranges between 26.6 °C and 29.7 °C; salinity between 1.3 and 30 psu; relative humidity close to 90%. Precipitation for the area ranges between 5000-7000 mm per year, semidiurnal tides with an average range of 4.1 m ( Cantera and Blanco 2001).

Differential diagnosis.

Bestiolina of small size (female 0.64-0.73 mm, male 0.63-0.75 mm), with body divided in prosome and slender urosome. Cephalic dorsal hump present in male. Rostrum short and stout divided in acute points. First pedigerous somite fused with cephalothorax, fifth pedigerous somite separated from preceding somite. Posterolateral margins of fifth pedigerous somite rounded and ornamented with small spinules. Genital double-somite with ventral protuberance in adult females. Exopods of legs 2-4 with anterior and posterior surfaces of all segments without spinules. Endopod 2 of legs 2 and 3 with anterior surface mostly with 3 small spinules and posterior surface mostly with 4 large spinules. Leg 5 of female rudimentary, unsegmented, consisting of a pair of rounded lobes, lobes with smooth margin. Leg 5 of male asymmetrical, right leg as in female, left leg long, 5-segmented, last segment with long distal spine.

Description of holotype female.

(Fig. 2A) Length of specimen measured from tip of rostrum to posterior margin of caudal rami: 0.70 mm. Body robust, widest section at second somite, anterior part of cephalosome rounded. Rostrum short and stout, divided into acute points (Fig. 2B). First pedigerous somite completely fused with cephalosome. Second, thirth and fourth pedigerous somites free. Fifth pedigerous somite completely separated from fourth, with posterolateral margins rounded and bearing small spinules (Fig. 2C).

Urosome, 4-segmented. First and second urosomites fused forming a ventrally expanded genital-double somite. Anal somite slightly longer than second and third urosomites together (Fig. 2D). Caudal rami not divergent, shorter than anal somite, armed with 5 setae. Dorsal setae (VII) strongly reduced, setae I and II lacking ( Huys and Boxshall 1991). Without setae on the inner and outer sides of rami (Fig. 2E).

Antennule 24-segmented (Fig. 3A). Ancestral segments ( Huys and Boxshall 1991) I - IV and XXVII–XXVIII fused. Armature formula with current segments designated with Arabic numerals (s = seta, sp = spine, ae = aesthetask): 1:6s, 2:2s, 3:1s, 4:2s, 5:1s, 6-8:2s, 9-12:1s, 13:0s, 14:2s, 15:1s, 16:1s, 17:1ae, 18:2s, 19:1s, 20:1ae, 21 to 23:2s, 24:4s+1sp.

Antenna (Fig. 3B) biramous. Coxa small, partially fused with basis, with 1 seta. Basis with 2 long distal seate. Endopod 2-segmented, first segment with 2 subdistal setae, second segment bilobated, subterminal lobe with 8 setae, terminal lobe with 7 setae. Exopod 7-segmented, first and second segments fused, each with 2 setae, segments 3-6 each with 1 seta, terminal segment with 3 setae.

Mandible (Fig. 3C) with thick gnathobase armed with 3 medial teeth, 4 dorsal teeth, 1 large anterior tooth separated from main cuting edge by a diastemma, and a short dorsal seta. Palp basis with 4 subequal setae; endopod 2-segmented, first segment with 4 distal setae, second segment with 11 subequal setae; exopod short, 5-segmented, each segment with 1 seta except distal segment with 2.

The maxillule, maxilla and maxilliped are described according to Ferrari and Ivanenko (2008).

Maxillule (Fig. 3D) with precoxal endite bearing 9 thick spiniform setae. Coxa with 2 endites, each endite with 3 setae, exite with 9 setae. Basis with 4 setae on inner margin; distal endite bilobated with 6 setae on short lobe and 7 setae on long lobe. Exopod with 11 setae.

Maxilla (Fig. 3E), precoxal endite of syncoxa armed with 5 setae. Three coxal endites each with 3 setae. Basis with 3 setae. Endopod 3-segmented, first segment with endite bearing 1 seta, second segment with 2 setae, third segment with 3 setae.

Maxilliped (Fig. 3F) long. Coxa armed with 4 groups of elements: proximal endite of praecoxa reduced to 1 thick seta, middle endite of praecoxa represented by 1 thick and 1 thin seta, distal endite of praecoxa consists of 2 thin setae, endite of coxa represented by 4 subequal setae. Distal endite of basis with 3 setae. Endopod 6-segmented, setal formula of first 4 segments 2, 3, 1, 3, fifth segment bilobated with 1 and 2 setae on each lobe (each side), distal segment with 4 setae.

Leg 1 (Fig. 4A): coxa with row of short setae on inner margin, and 2 setae on outer margin. Basis with 1 seta on inner margin. Exopod 3-segmented; first segment with 1 spine distally on outer margin, inner margin with 1 seta; second segment, outer margin naked, inner margin with 1 seta; third segment outer margin with 2 setae, distal margin with 1 seta, inner margin with 4 setae. Endopod 2-segmented; first segment, inner margin with 1 seta; second segment, outer margin with 1 seta, distal margin and inner margins each with 2 setae. Anterior and posterior surfaces of all segments without spinules.

Legs 2 to 4 (Fig. 4 B–D): coxa with 1 seta on inner margin. Basis without marginal seta. Legs with 3-segmented exopod and endopod. Exopod, first and second segments, outer margin with 1 short and thick distal spine, first segment inner margin with 1 seta (leg 2) or without seta (leg 3 and 4); third segment, outer margin with 3 short and thick spines, 1 inserted medially, 2 inserted subapically, distal margin with 1 long spine, inner margin with 5 setae. Long spine of distal margin thicker on leg 3 and 4.

Leg 2 (Fig. 4B): exopod, anterior and posterior surfaces of all 3 segments without spinules. Endopod, anterior and posterior surfaces of first and third segment without spinules, second segment, anterior surface with 3 short spinules, posterior surface with 4 long spinules.

Leg 3 (Fig. 4C): number and size of spinules of anterior and posterior surfaces like leg 2. Distal segment of endopods of legs 3 and 4 with 6 setae.

Leg 4 (Fig. 4D): exopod and endopod, anterior and posterior surfaces of all segments without spinules.

Leg 5 (Fig. 4E): reduced in size, represented by symmetrical lobes with smooth margins.

Spine (Roman numerals) and setal (Arabic numerals) formula of legs 1-4 as follows:

Description of male (Fig. 5A): length of allotype measured from tip of rostrum to tip of caudal rami: 0.70 mm. Body more slender and slightly longer than in female. Cephalothorax with dorsal hump. Antennule 20-segmented, setation patterns of ancestral segments (indicated with Arabic numerals, s = seta), as follow: 1:3s, 2:1s, 3:1s, 4:1s, 5 and 8:0s, 9:1s, 10 and 12:0s, 13:1s, 14 and 15:0s, 16:1s, 17:0s, 18:1s, 19:1s, 20:4s.

First to fifth pedigerous somites and swimming legs like in female. Urosome 5-segmented. Leg 5 (Fig. 5B) typical for the family, right leg consisting of a rounded lobe as in female, left leg elongate, 5-segmented, distal segment with apical spine.

Variability (Table 1): Females (n = 13): morphological variability in body length x̄ = 0.70 ± 0.03 (0.64-0.73 mm) and in ornamentation pattern (number of spinules) of endopod 2 of legs 2 and 3.

Leg 2, endopod 2: holotype and 1 paratype (NHMW 26311) with 3 short spinules on anterior surface and 4 long spinules on posterior surface of left and right legs, one paratype (NHMW 26310) shows an additional spinule on anterior surface (4 instead of 3) of right leg, one paratype (NHMW 26311) shows an additional spinule on posterior surface of same leg. Two paratypes (MAKURIWA INV-CRU8993, NHMW 26309) show a different combination of spinules: one additional spinule on the anterior surface of both legs (left and right) (4 instead 3) and 1 additional spinule on posterior surface of left and right legs (5 instead of 4) MAKURIWA (Table 1).

Leg 3, endopod 2: variability of the ornamentation pattern was also noted on this leg but less accentuated than in leg 2 (Table 1). Anterior surface with 3 short spinules on anterior surface and 4 long spinules on posterior surface (holotype and paratype NHMW 26310) on both left and right legs; one paratype (MAKURIWA INV-CRU8993) shows 1 additional spinule on both legs on anterior and posterior surfaces (4+5 instead of 3+4). One paratype (NHMW 26309) shows 1 additional spinule on posterior surface (total 3+5) of left leg. In general, the most common spinulation pattern of second endopods in legs 2 and 3 is 3 spinules on anterior surface and 4 on posterior surface.

Males (n = 3) show variability on body length x̄ = 0.70 ± 0.06 (0.63-0.75 mm). No variability was noted on spinulation pattern of the 3 studied specimens.