Laophonte paradduensis, Gómez & Morales-Serna, 2013
Gómez, S. & Morales-Serna, F. N., 2013, On a small collection of Laophontidae T. Scott (Copepoda: Harpacticoida) from Mexico. I. New species and new records of Laophonte Philippi and Paralaophonte Lang, Journal of Natural History 47 (5 - 12), pp. 329-380: 330-340
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Laophonte paradduensis sp. nov.
One dissected female holotype (EMUCOP-020591-02), one dissected female paratype (EMUCOP-020591-01) and one dissected male paratype (EMUCOP-020591-03). Collected from Ensenada del Pabellón lagoon (Sinaloa State, north-western Mexico) (24 ◦ 19 ′ – 24 ◦ 35 ′ N, 107 ◦ 28 ′ – 107 ◦ 45 ′ W), 2 May 1991, stn. 3 (see Gómez-Noguera and Hendrickx, 1997), brackish, less than 2 m depth, 0.045 µmolN / g, 0.837 µmolC / g, fine sand, coll. S. Gómez. GoogleMaps
The specific epithet makes reference to the similarity between Laophonte adduensis Sewell and the herein newly described species.
Female. The two specimens were badly damaged during sample processing. Habitus (not shown), fusiform. Total body length measured from tip of rostrum to posterior margin of caudal rami, 585 µm and 619 µm. Rostrum (not shown) fused to cephalic shield, with bilobed tip flanked by pair of sensilla. Genital-double somite distinct dorsally ( Figure 1A View Figure 1 ) and laterally; fused ventrally ( Figure 1B View Figure 1 ), with subtle internal rib indicating former division; genital half with partially crenulated posterior margin dorsally, lateral processes well developed, with a sensillum arising from bulbous structure with small denticles (contrary to spinules, these are not articulated basally), with short spinular row close to outer proximal corners ventrally; second half of genital double-somite as previous somite dorsally, lateral processes well developed but without sensilla, with two medial tube pores and with row of minute spinules along posterior margin ventrally. Fourth urosomite as previous somite, lateral processes well developed, with sensilla arising from bulbous structure as in genital somite. Posterior margin of fifth urosomite completely crenulated dorsally; ventral spinules along posterior margin comparatively larger than in previous somites, with two tube-pores. Anal somite with two dorsal and two ventral pores; margin close to insertion site of caudal rami plain dorsally, with spinules ventrally; anal operculum rounded, crenulated and flanked by two sensilla. Caudal rami ( Figure 1A–C View Figure 1 ) about 2.3 times as long as wide, with seven setae; seta I small, seta II dorsal to and about 4.3 times as long as seta I, seta III situated laterally close to distal outer corner, seta IV arising on distal outer corner and smaller than seta III, seta V longest and without fracture plan, seta VI arising at inner distal corner and as long as seta IV, seta VII situated dorsally on distal fifth and triarticulated at base.
Antennule ( Figure 2A View Figure 2 ) four-segmented; first segment with medial and distal small inner spinules, with small process (arrowed in Figure 2A View Figure 2 ); process on second segment (arrowed in Figure 2A View Figure 2 ) comparatively larger than in previous segment, and noticeably smaller than segment width; first and second segments about as long as wide; third segment longest, about three times as long as wide, with several rows of outer denticles (spinules?); fourth segment smallest. Armature formula, I-(1); II-(7) (two setae missing in Figure 2A View Figure 2 ); III-(10 + ae); IV-(8 + acrothek) (acrothek consisting of two setae and one aesthetasc fused at their bases).
Antenna ( Figure 2B View Figure 2 ). Allobasis with one abexopodal seta, and with inner spinules. Exopod one-segmented, with two lateral (proximal one slender, naked) and two distal elements. Free endopodal segment with inner row of spinules and one outer frill, with two spines and one slender seta laterally, and two strong spines, two geniculate single setae, and one geniculate seta fused to tiny element basally.
Mandible ( Figure 2C, D View Figure 2 ). Strong gnathobase with bi- and multicuspidate teeth distally, and one pinnate seta laterally. Palp one-segment, with some proximal spinules, and with three lateral setae (proximal one small) and one apical strong element.
Maxillule ( Figure 2E View Figure 2 ). Praecoxal arthrite with five strong apical spines ornamented as shown, two lateral slender setae and some spinules. Coxa with one strong seta. Basis with three apical elements. Exopod seemingly one-segmented, small, with two seta (one of them very small). Endopod represented by two long setae.
Maxilla ( Figure 4A, B View Figure 4 ). Syncoxa with outer and inner spinules as depicted; with three endites; proximal endite represented by single seta, middle and distal endites with three elements each as figured (one of them fused to endite). Allobasis drawn into strong claw with one accessory seta. Endopod represented by two long setae.
Maxilliped ( Figure 4C View Figure 4 ). Syncoxa with spinular rows as depicted, and with one distal seta. Basis with small spinules along palmar margin. Endopod drawn out into claw with one accompanying seta.
P1 ( Figure 3A View Figure 3 ). Coxa with several spinule rows as figured. Basis with longitudinal rows of spinules on anterior and posterior surface, with naked inner element and pinnate outer spine-like element. Rami two-segmented. Exopod not reaching middle of ENP1; EXP1 about twice as long as wide and about half total length of EXP2, with one outer spine; EXP2 with two outer spines and three geniculate setae apically. Endopod robust and elongate; ENP1 long, about 3.4 times as long as wide, without ornamentation; ENP2 about 1.5 times as long as wide, without spinules, with one small apical seta and one strong claw, the latter about 2.4 times as long as supporting segment.
P2 ( Figure 3B View Figure 3 ). Coxa with spinular rows as figured; distal outer corner produced and furnished with fine spinules. Basis with spinules at base of outer seta and between rami. Exopod three-segmented; EXP1 without, EXP2 with inner seta; EXP3 with three outer spines, two apical and one inner element. Endopod two-segmented, reaching insertion site of inner seta of EXP2; ENP1 with one inner seta; ENP2 with two inner and two apical setae.
P3 ( Figure 4D View Figure 4 ). Coxa and basis as in P2. Exopod three-segmented; first segment without, second segment with inner seta; third segment with three outer spines, two apical and two inner elements. Endopod two-segmented, not reaching insertion site of inner seta of EXP2; ENP1 with one inner seta; ENP2 with three inner, two apical and one outer element.
P4 ( Figure 5A View Figure 5 ). Coxa, basis and exopod as in P3. Endopod barely reaching tip of EXP1; two-segmented; ENP1 with one inner seta; ENP2 with two inner setae, two apical and one outer element.
P5 ( Figure 5B View Figure 5 ) large, with separate rami. Baseoendopodal lobe well developed, elongate, with reticulated surface, and with fine spinules along margins as shown; with five setae plus outer basal seta, the latter arising from short setophore. Exopod ovate, with spinules along inner and outer margin, with six setae.
Armature formula of P1–P5 as in Table 1.
Male. The only male specimen was badly damaged during sample processing. Total body length, 600 µm measured from tip of rostrum to posterior margin of caudal rami. Habitus (not shown) as in female, except for separate second and third urosomites, and for comparatively stronger spinules along posterior margin of fourth and fifth urosomites ventrally ( Figure 6A View Figure 6 ).
P1, P2 and P4 as in female.
P3 EXP as in female; P3 ENP dimorphic ( Figure 6B View Figure 6 ), three-segmented, first segment as in female, second segment with inner seta and outer apophysis (the latter homologous to outer seta of the female P3 ENP2), third segment with two inner and two apical setae.
Left and right P5 fused ( Figure 6C View Figure 6 ); baseoendopodal lobe poorly developed and fused to exopod, with two setae plus outer basal seta; exopod with four setae.
P6 ( Figure 6D View Figure 6 ) represented by two setae.
Sewell (1940) described Laophonte adduensis based on two females collected from the Maldive Archipelago. In his description, Sewell (1940: 315) described and illustrated the first segment of the female antennule with a “rounded knob-like process”, but remained silent about a process on the second segment. Also, Sewell (1940) showed the third segment of the female antennule without any sort of ornamentation. In that same paper, Sewell (1940) made the first attempt to define coherent species groups within the genus Laophonte , and united L. cornuta Philippi and L. adduensis in his group II(iv)(a), defined by the presence of a two-segmented P1 EXP, a four-segmented antennule, and by the presence of six and five setae on the P5 EXP and baseoendopodal lobe, respectively (see also Gómez and Boyko, 2006, for a more detailed account). Nicholls (1941),
probably unaware of Sewell’s (1940) description of L. adduensis , subdivided the genus Laophonte into five subgenera based mainly on the setation of the female P3 ENP2 (L. ( Neolaophonte ) Nicholls, L. ( Metalaophonte ) Nicholls, L. ( Monolaophonte ) Nicholls, L. ( Mesolaophonte ) Nicholls and L. ( Laophonte ) Nicholls). Nicholls (1941) defined his L. ( Laophonte ) based on the presence of two inner and two apical setae (without outer elements) on P2 ENP2 (except for some species, which show either one outer seta or one inner element), of three inner, two apical and one outer seta on the female P3 ENP2, and a variable armature formula of P4 ENP2. He further subdivided this subgenus into five species groups ( cornuta -, typhlops -, brevirostris -, stromi - and mohammed -groups) and recognized a number of species that did not classify into any of his groups. Among other species, Nicholls (1941) included L. cornuta in his cornuta -group, which was also defined by the presence of a “spur” on the second antennulary segment and by the female P5 of cornuta type. Some years later, Nicholls (1944, 1945) redescribed the female of L. adduensis and gave the first description of the male based on material collected by Dr Robert Gurney from Ghardaqa (Red Sea) (Nichols 1944), and from the reef fringing Leander Point in Port Denison (Western Australia) (Nichols 1945). In his papers, Nichols (1944, 1945) confirmed the presence of a small process on the first segment of the female antennule, the lack of any sort of process on the second segment, and the lack of a spur (sic) on the last segment, and observed two small differences in the males from Western Australia and the Red Sea, attributable to geographic variability.
In a third attempt to delimit boundaries between species groups in Laophonte, Lang (1944 , 1948), seemingly unaware of Nicholls’ (1944, 1945) papers, rejected Nicholls’ (1941) view and recognized seven species groups, with the cornuta group only including L. cornuta . Lang (1944, 1948) defined this group by a four-segmented female antennule, with acute thorns on segments I and II, caudal rami twice as long as broad, the two-segmented P1 EXP and P4 ENP, six and five setae on the female P5 EXP and baseoendopod, respectively, and two elements on the male P5 baseoendopod, and by the armature formula presented by Lang (1944, table 2: 32). Some years later, Noodt (1964) described L. ciliata Noodt , which he allocated to the cornuta -group himself, along with L. cornuta and L. adduensis . Fiers (1986) added L. expansa Fiers and L. plana Fiers to the same group, and the last addition has been L. similicornuta Gómez and Boyko ( Gómez and Boyko 2006) .
Certain authors (i.e. Fiers 1986; Huys and Lee 2000) have recognized the polyphyletic status of the genus Laophonte , and also suggested removing the cornuta -group to a new genus, because this clade can be supported by the presence of two segments distal to the geniculation of the male antennule and by the presence of only two setae on the maxillulary endopod ( Huys and Lee 2000). However this would require re-evaluation, updating diagnoses and reallocation of remaining species to either existing or new genera ( Fiers 1986; Huys and Lee 2000).
The female of the new species can be attributed to the cornuta -group as defined by Lang (1944, 1948), and it agrees with Huys and Lee’s (2000) apomorphy 14 (only two setae on the maxillulary endopod). Laophonte paradduensis sp. nov. and L. adduensis are unique within the cornuta -group by the presence of a small process (smaller than width of segment) on the second segment of the antennule and by the presence of a small lateral seta on the exopod of the antenna (instead of a very strong hook-shaped process on the second segment of the antennule and subequal setae on the exopod of the antenna in the remaining species of the group).
Laophonte adduensis and L. paradduensis can be distinguished from each other by the armature formula of the P2 EXP3 (three outer spines in L. paradduensis , two in L. adduensis and similar to L. ciliata ), the presence of an acute projection on segment 2 of the female antennule smaller than width of segment in L. paradduensis (absent in L. adduensis ), the relative length of the caudal rami (about 2.3 times as long as wide in L. paradduensis , three times as long as wide in L. adduensis ), the relative length of P3 and P4 ENP (in L. adduensis reaching insertion of inner seta of P3 and P4 EXP2, respectively, comparatively shorter in L. paradduensis ), the relative length of the setae on female P5 EXP and BENP (comparatively longer in L. paradduensis ), and by the shape of the apophysis on male P3 ENP2 (with an acute small projection of variable size in L. adduensis , plain in L. paradduensis ).
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